| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Xiao Guangrong | 4462 | 17.65% | 111 | 15.00% |
| Paolo Bonzini | 4150 | 16.41% | 62 | 8.38% |
| Sean Christopherson | 3535 | 13.98% | 154 | 20.81% |
| Avi Kivity | 2281 | 9.02% | 90 | 12.16% |
| Marcelo Tosatti | 1986 | 7.85% | 34 | 4.59% |
| Junaid Shahid | 1895 | 7.49% | 27 | 3.65% |
| Takuya Yoshikawa | 945 | 3.74% | 37 | 5.00% |
| Ben Gardon | 905 | 3.58% | 34 | 4.59% |
| Joerg Roedel | 826 | 3.27% | 17 | 2.30% |
| Vitaly Kuznetsov | 667 | 2.64% | 15 | 2.03% |
| Kai Huang | 333 | 1.32% | 7 | 0.95% |
| Eddie Dong | 322 | 1.27% | 7 | 0.95% |
| Wanpeng Li | 245 | 0.97% | 4 | 0.54% |
| Huaitong Han | 239 | 0.95% | 1 | 0.14% |
| Gleb Natapov | 229 | 0.91% | 10 | 1.35% |
| Andrea Arcangeli | 229 | 0.91% | 3 | 0.41% |
| Lan Tianyu | 217 | 0.86% | 7 | 0.95% |
| Izik Eidus | 208 | 0.82% | 6 | 0.81% |
| Yang Zhang | 193 | 0.76% | 1 | 0.14% |
| Brijesh Singh | 133 | 0.53% | 2 | 0.27% |
| Peter Feiner | 129 | 0.51% | 4 | 0.54% |
| Yu Zhang | 116 | 0.46% | 3 | 0.41% |
| Nadav Har'El | 100 | 0.40% | 2 | 0.27% |
| Jiří Paleček | 77 | 0.30% | 1 | 0.14% |
| David Matlack | 58 | 0.23% | 4 | 0.54% |
| Huang Ying | 57 | 0.23% | 2 | 0.27% |
| Dave Hansen | 51 | 0.20% | 2 | 0.27% |
| Wei Yang | 48 | 0.19% | 3 | 0.41% |
| Xiantao Zhang | 47 | 0.19% | 3 | 0.41% |
| Davidlohr Bueso A | 46 | 0.18% | 1 | 0.14% |
| Andres Lagar-Cavilla | 43 | 0.17% | 2 | 0.27% |
| David Chinner | 42 | 0.17% | 2 | 0.27% |
| Arnd Bergmann | 32 | 0.13% | 2 | 0.27% |
| Jim Mattson | 32 | 0.13% | 2 | 0.27% |
| Tom Lendacky | 31 | 0.12% | 3 | 0.41% |
| Nadav Amit | 31 | 0.12% | 3 | 0.41% |
| David L Stevens | 30 | 0.12% | 1 | 0.14% |
| Jason Baron | 27 | 0.11% | 1 | 0.14% |
| Feng Wu | 18 | 0.07% | 2 | 0.27% |
| Sheng Yang | 17 | 0.07% | 4 | 0.54% |
| Mohammed Gamal | 16 | 0.06% | 2 | 0.27% |
| Xiaoguang Chen | 15 | 0.06% | 1 | 0.14% |
| Peter Xu | 14 | 0.06% | 2 | 0.27% |
| Ladi Prosek | 14 | 0.06% | 2 | 0.27% |
| Wei Yongjun | 12 | 0.05% | 2 | 0.27% |
| Andre Przywara | 12 | 0.05% | 2 | 0.27% |
| Ying Han | 11 | 0.04% | 1 | 0.14% |
| Dan J Williams | 10 | 0.04% | 1 | 0.14% |
| Jike Song | 10 | 0.04% | 1 | 0.14% |
| Lai Jiangshan | 10 | 0.04% | 3 | 0.41% |
| Li RongQing | 10 | 0.04% | 1 | 0.14% |
| Stephen Zhang | 9 | 0.04% | 1 | 0.14% |
| Eric Northup | 8 | 0.03% | 1 | 0.14% |
| Bandan Das | 8 | 0.03% | 3 | 0.41% |
| Jay Zhou | 7 | 0.03% | 1 | 0.14% |
| Liang Chen | 7 | 0.03% | 2 | 0.27% |
| Hillf Danton | 6 | 0.02% | 1 | 0.14% |
| Ingo Molnar | 6 | 0.02% | 4 | 0.54% |
| Radim Krčmář | 6 | 0.02% | 1 | 0.14% |
| Hao Peng | 5 | 0.02% | 2 | 0.27% |
| Tejun Heo | 5 | 0.02% | 2 | 0.27% |
| Eric W. Biedermann | 5 | 0.02% | 2 | 0.27% |
| Paul Gortmaker | 4 | 0.02% | 1 | 0.14% |
| Dominik Dingel | 4 | 0.02% | 1 | 0.14% |
| Borislav Petkov | 4 | 0.02% | 1 | 0.14% |
| Eduardo Pereira Habkost | 3 | 0.01% | 1 | 0.14% |
| Anthony Liguori | 3 | 0.01% | 2 | 0.27% |
| Hannes Eder | 3 | 0.01% | 1 | 0.14% |
| Thomas Gleixner | 3 | 0.01% | 2 | 0.27% |
| Haozhong Zhang | 2 | 0.01% | 1 | 0.14% |
| Jan Kiszka | 2 | 0.01% | 1 | 0.14% |
| Gui Jianfeng | 2 | 0.01% | 1 | 0.14% |
| Shakeel Butt | 2 | 0.01% | 1 | 0.14% |
| Gustavo A. R. Silva | 2 | 0.01% | 1 | 0.14% |
| Harvey Harrison | 2 | 0.01% | 1 | 0.14% |
| Joe Perches | 2 | 0.01% | 1 | 0.14% |
| Zhao Jin | 1 | 0.00% | 1 | 0.14% |
| Mauro Carvalho Chehab | 1 | 0.00% | 1 | 0.14% |
| Tiejun Chen | 1 | 0.00% | 1 | 0.14% |
| KarimAllah Ahmed | 1 | 0.00% | 1 | 0.14% |
| Mark Rutland | 1 | 0.00% | 1 | 0.14% |
| Mike Day | 1 | 0.00% | 1 | 0.14% |
| Xudong Hao | 1 | 0.00% | 1 | 0.14% |
| David Woodhouse | 1 | 0.00% | 1 | 0.14% |
| Boqun Feng | 1 | 0.00% | 1 | 0.14% |
| Miaohe Lin | 1 | 0.00% | 1 | 0.14% |
| Total | 25286 | 740 |
// SPDX-License-Identifier: GPL-2.0-only /* * Kernel-based Virtual Machine driver for Linux * * This module enables machines with Intel VT-x extensions to run virtual * machines without emulation or binary translation. * * MMU support * * Copyright (C) 2006 Qumranet, Inc. * Copyright 2010 Red Hat, Inc. and/or its affiliates. * * Authors: * Yaniv Kamay <yaniv@qumranet.com> * Avi Kivity <avi@qumranet.com> */ #include "irq.h" #include "ioapic.h" #include "mmu.h" #include "mmu_internal.h" #include "tdp_mmu.h" #include "x86.h" #include "kvm_cache_regs.h" #include "kvm_emulate.h" #include "cpuid.h" #include "spte.h" #include <linux/kvm_host.h> #include <linux/types.h> #include <linux/string.h> #include <linux/mm.h> #include <linux/highmem.h> #include <linux/moduleparam.h> #include <linux/export.h> #include <linux/swap.h> #include <linux/hugetlb.h> #include <linux/compiler.h> #include <linux/srcu.h> #include <linux/slab.h> #include <linux/sched/signal.h> #include <linux/uaccess.h> #include <linux/hash.h> #include <linux/kern_levels.h> #include <linux/kthread.h> #include <asm/page.h> #include <asm/memtype.h> #include <asm/cmpxchg.h> #include <asm/io.h> #include <asm/set_memory.h> #include <asm/vmx.h> #include <asm/kvm_page_track.h> #include "trace.h" extern bool itlb_multihit_kvm_mitigation; static int __read_mostly nx_huge_pages = -1; #ifdef CONFIG_PREEMPT_RT /* Recovery can cause latency spikes, disable it for PREEMPT_RT. */ static uint __read_mostly nx_huge_pages_recovery_ratio = 0; #else static uint __read_mostly nx_huge_pages_recovery_ratio = 60; #endif static int set_nx_huge_pages(const char *val, const struct kernel_param *kp); static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp); static const struct kernel_param_ops nx_huge_pages_ops = { .set = set_nx_huge_pages, .get = param_get_bool, }; static const struct kernel_param_ops nx_huge_pages_recovery_ratio_ops = { .set = set_nx_huge_pages_recovery_ratio, .get = param_get_uint, }; module_param_cb(nx_huge_pages, &nx_huge_pages_ops, &nx_huge_pages, 0644); __MODULE_PARM_TYPE(nx_huge_pages, "bool"); module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_ratio_ops, &nx_huge_pages_recovery_ratio, 0644); __MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint"); static bool __read_mostly force_flush_and_sync_on_reuse; module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); /* * When setting this variable to true it enables Two-Dimensional-Paging * where the hardware walks 2 page tables: * 1. the guest-virtual to guest-physical * 2. while doing 1. it walks guest-physical to host-physical * If the hardware supports that we don't need to do shadow paging. */ bool tdp_enabled = false; static int max_huge_page_level __read_mostly; static int max_tdp_level __read_mostly; enum { AUDIT_PRE_PAGE_FAULT, AUDIT_POST_PAGE_FAULT, AUDIT_PRE_PTE_WRITE, AUDIT_POST_PTE_WRITE, AUDIT_PRE_SYNC, AUDIT_POST_SYNC }; #ifdef MMU_DEBUG bool dbg = 0; module_param(dbg, bool, 0644); #endif #define PTE_PREFETCH_NUM 8 #define PT32_LEVEL_BITS 10 #define PT32_LEVEL_SHIFT(level) \ (PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS) #define PT32_LVL_OFFSET_MASK(level) \ (PT32_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \ * PT32_LEVEL_BITS))) - 1)) #define PT32_INDEX(address, level)\ (((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1)) #define PT32_BASE_ADDR_MASK PAGE_MASK #define PT32_DIR_BASE_ADDR_MASK \ (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1)) #define PT32_LVL_ADDR_MASK(level) \ (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \ * PT32_LEVEL_BITS))) - 1)) #include <trace/events/kvm.h> /* make pte_list_desc fit well in cache line */ #define PTE_LIST_EXT 3 struct pte_list_desc { u64 *sptes[PTE_LIST_EXT]; struct pte_list_desc *more; }; struct kvm_shadow_walk_iterator { u64 addr; hpa_t shadow_addr; u64 *sptep; int level; unsigned index; }; #define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \ for (shadow_walk_init_using_root(&(_walker), (_vcpu), \ (_root), (_addr)); \ shadow_walk_okay(&(_walker)); \ shadow_walk_next(&(_walker))) #define for_each_shadow_entry(_vcpu, _addr, _walker) \ for (shadow_walk_init(&(_walker), _vcpu, _addr); \ shadow_walk_okay(&(_walker)); \ shadow_walk_next(&(_walker))) #define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \ for (shadow_walk_init(&(_walker), _vcpu, _addr); \ shadow_walk_okay(&(_walker)) && \ ({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \ __shadow_walk_next(&(_walker), spte)) static struct kmem_cache *pte_list_desc_cache; struct kmem_cache *mmu_page_header_cache; static struct percpu_counter kvm_total_used_mmu_pages; static void mmu_spte_set(u64 *sptep, u64 spte); static union kvm_mmu_page_role kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu); #define CREATE_TRACE_POINTS #include "mmutrace.h" static inline bool kvm_available_flush_tlb_with_range(void) { return kvm_x86_ops.tlb_remote_flush_with_range; } static void kvm_flush_remote_tlbs_with_range(struct kvm *kvm, struct kvm_tlb_range *range) { int ret = -ENOTSUPP; if (range && kvm_x86_ops.tlb_remote_flush_with_range) ret = static_call(kvm_x86_tlb_remote_flush_with_range)(kvm, range); if (ret) kvm_flush_remote_tlbs(kvm); } void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, u64 start_gfn, u64 pages) { struct kvm_tlb_range range; range.start_gfn = start_gfn; range.pages = pages; kvm_flush_remote_tlbs_with_range(kvm, &range); } bool is_nx_huge_page_enabled(void) { return READ_ONCE(nx_huge_pages); } static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, unsigned int access) { u64 spte = make_mmio_spte(vcpu, gfn, access); trace_mark_mmio_spte(sptep, gfn, spte); mmu_spte_set(sptep, spte); } static gfn_t get_mmio_spte_gfn(u64 spte) { u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask; gpa |= (spte >> SHADOW_NONPRESENT_OR_RSVD_MASK_LEN) & shadow_nonpresent_or_rsvd_mask; return gpa >> PAGE_SHIFT; } static unsigned get_mmio_spte_access(u64 spte) { return spte & shadow_mmio_access_mask; } static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) { u64 kvm_gen, spte_gen, gen; gen = kvm_vcpu_memslots(vcpu)->generation; if (unlikely(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS)) return false; kvm_gen = gen & MMIO_SPTE_GEN_MASK; spte_gen = get_mmio_spte_generation(spte); trace_check_mmio_spte(spte, kvm_gen, spte_gen); return likely(kvm_gen == spte_gen); } static gpa_t translate_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u32 access, struct x86_exception *exception) { /* Check if guest physical address doesn't exceed guest maximum */ if (kvm_vcpu_is_illegal_gpa(vcpu, gpa)) { exception->error_code |= PFERR_RSVD_MASK; return UNMAPPED_GVA; } return gpa; } static int is_cpuid_PSE36(void) { return 1; } static int is_nx(struct kvm_vcpu *vcpu) { return vcpu->arch.efer & EFER_NX; } static gfn_t pse36_gfn_delta(u32 gpte) { int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT; return (gpte & PT32_DIR_PSE36_MASK) << shift; } #ifdef CONFIG_X86_64 static void __set_spte(u64 *sptep, u64 spte) { WRITE_ONCE(*sptep, spte); } static void __update_clear_spte_fast(u64 *sptep, u64 spte) { WRITE_ONCE(*sptep, spte); } static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) { return xchg(sptep, spte); } static u64 __get_spte_lockless(u64 *sptep) { return READ_ONCE(*sptep); } #else union split_spte { struct { u32 spte_low; u32 spte_high; }; u64 spte; }; static void count_spte_clear(u64 *sptep, u64 spte) { struct kvm_mmu_page *sp = sptep_to_sp(sptep); if (is_shadow_present_pte(spte)) return; /* Ensure the spte is completely set before we increase the count */ smp_wmb(); sp->clear_spte_count++; } static void __set_spte(u64 *sptep, u64 spte) { union split_spte *ssptep, sspte; ssptep = (union split_spte *)sptep; sspte = (union split_spte)spte; ssptep->spte_high = sspte.spte_high; /* * If we map the spte from nonpresent to present, We should store * the high bits firstly, then set present bit, so cpu can not * fetch this spte while we are setting the spte. */ smp_wmb(); WRITE_ONCE(ssptep->spte_low, sspte.spte_low); } static void __update_clear_spte_fast(u64 *sptep, u64 spte) { union split_spte *ssptep, sspte; ssptep = (union split_spte *)sptep; sspte = (union split_spte)spte; WRITE_ONCE(ssptep->spte_low, sspte.spte_low); /* * If we map the spte from present to nonpresent, we should clear * present bit firstly to avoid vcpu fetch the old high bits. */ smp_wmb(); ssptep->spte_high = sspte.spte_high; count_spte_clear(sptep, spte); } static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) { union split_spte *ssptep, sspte, orig; ssptep = (union split_spte *)sptep; sspte = (union split_spte)spte; /* xchg acts as a barrier before the setting of the high bits */ orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low); orig.spte_high = ssptep->spte_high; ssptep->spte_high = sspte.spte_high; count_spte_clear(sptep, spte); return orig.spte; } /* * The idea using the light way get the spte on x86_32 guest is from * gup_get_pte (mm/gup.c). * * An spte tlb flush may be pending, because kvm_set_pte_rmapp * coalesces them and we are running out of the MMU lock. Therefore * we need to protect against in-progress updates of the spte. * * Reading the spte while an update is in progress may get the old value * for the high part of the spte. The race is fine for a present->non-present * change (because the high part of the spte is ignored for non-present spte), * but for a present->present change we must reread the spte. * * All such changes are done in two steps (present->non-present and * non-present->present), hence it is enough to count the number of * present->non-present updates: if it changed while reading the spte, * we might have hit the race. This is done using clear_spte_count. */ static u64 __get_spte_lockless(u64 *sptep) { struct kvm_mmu_page *sp = sptep_to_sp(sptep); union split_spte spte, *orig = (union split_spte *)sptep; int count; retry: count = sp->clear_spte_count; smp_rmb(); spte.spte_low = orig->spte_low; smp_rmb(); spte.spte_high = orig->spte_high; smp_rmb(); if (unlikely(spte.spte_low != orig->spte_low || count != sp->clear_spte_count)) goto retry; return spte.spte; } #endif static bool spte_has_volatile_bits(u64 spte) { if (!is_shadow_present_pte(spte)) return false; /* * Always atomically update spte if it can be updated * out of mmu-lock, it can ensure dirty bit is not lost, * also, it can help us to get a stable is_writable_pte() * to ensure tlb flush is not missed. */ if (spte_can_locklessly_be_made_writable(spte) || is_access_track_spte(spte)) return true; if (spte_ad_enabled(spte)) { if ((spte & shadow_accessed_mask) == 0 || (is_writable_pte(spte) && (spte & shadow_dirty_mask) == 0)) return true; } return false; } /* Rules for using mmu_spte_set: * Set the sptep from nonpresent to present. * Note: the sptep being assigned *must* be either not present * or in a state where the hardware will not attempt to update * the spte. */ static void mmu_spte_set(u64 *sptep, u64 new_spte) { WARN_ON(is_shadow_present_pte(*sptep)); __set_spte(sptep, new_spte); } /* * Update the SPTE (excluding the PFN), but do not track changes in its * accessed/dirty status. */ static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) { u64 old_spte = *sptep; WARN_ON(!is_shadow_present_pte(new_spte)); if (!is_shadow_present_pte(old_spte)) { mmu_spte_set(sptep, new_spte); return old_spte; } if (!spte_has_volatile_bits(old_spte)) __update_clear_spte_fast(sptep, new_spte); else old_spte = __update_clear_spte_slow(sptep, new_spte); WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); return old_spte; } /* Rules for using mmu_spte_update: * Update the state bits, it means the mapped pfn is not changed. * * Whenever we overwrite a writable spte with a read-only one we * should flush remote TLBs. Otherwise rmap_write_protect * will find a read-only spte, even though the writable spte * might be cached on a CPU's TLB, the return value indicates this * case. * * Returns true if the TLB needs to be flushed */ static bool mmu_spte_update(u64 *sptep, u64 new_spte) { bool flush = false; u64 old_spte = mmu_spte_update_no_track(sptep, new_spte); if (!is_shadow_present_pte(old_spte)) return false; /* * For the spte updated out of mmu-lock is safe, since * we always atomically update it, see the comments in * spte_has_volatile_bits(). */ if (spte_can_locklessly_be_made_writable(old_spte) && !is_writable_pte(new_spte)) flush = true; /* * Flush TLB when accessed/dirty states are changed in the page tables, * to guarantee consistency between TLB and page tables. */ if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { flush = true; kvm_set_pfn_accessed(spte_to_pfn(old_spte)); } if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { flush = true; kvm_set_pfn_dirty(spte_to_pfn(old_spte)); } return flush; } /* * Rules for using mmu_spte_clear_track_bits: * It sets the sptep from present to nonpresent, and track the * state bits, it is used to clear the last level sptep. * Returns non-zero if the PTE was previously valid. */ static int mmu_spte_clear_track_bits(u64 *sptep) { kvm_pfn_t pfn; u64 old_spte = *sptep; if (!spte_has_volatile_bits(old_spte)) __update_clear_spte_fast(sptep, 0ull); else old_spte = __update_clear_spte_slow(sptep, 0ull); if (!is_shadow_present_pte(old_spte)) return 0; pfn = spte_to_pfn(old_spte); /* * KVM does not hold the refcount of the page used by * kvm mmu, before reclaiming the page, we should * unmap it from mmu first. */ WARN_ON(!kvm_is_reserved_pfn(pfn) && !page_count(pfn_to_page(pfn))); if (is_accessed_spte(old_spte)) kvm_set_pfn_accessed(pfn); if (is_dirty_spte(old_spte)) kvm_set_pfn_dirty(pfn); return 1; } /* * Rules for using mmu_spte_clear_no_track: * Directly clear spte without caring the state bits of sptep, * it is used to set the upper level spte. */ static void mmu_spte_clear_no_track(u64 *sptep) { __update_clear_spte_fast(sptep, 0ull); } static u64 mmu_spte_get_lockless(u64 *sptep) { return __get_spte_lockless(sptep); } /* Restore an acc-track PTE back to a regular PTE */ static u64 restore_acc_track_spte(u64 spte) { u64 new_spte = spte; u64 saved_bits = (spte >> SHADOW_ACC_TRACK_SAVED_BITS_SHIFT) & SHADOW_ACC_TRACK_SAVED_BITS_MASK; WARN_ON_ONCE(spte_ad_enabled(spte)); WARN_ON_ONCE(!is_access_track_spte(spte)); new_spte &= ~shadow_acc_track_mask; new_spte &= ~(SHADOW_ACC_TRACK_SAVED_BITS_MASK << SHADOW_ACC_TRACK_SAVED_BITS_SHIFT); new_spte |= saved_bits; return new_spte; } /* Returns the Accessed status of the PTE and resets it at the same time. */ static bool mmu_spte_age(u64 *sptep) { u64 spte = mmu_spte_get_lockless(sptep); if (!is_accessed_spte(spte)) return false; if (spte_ad_enabled(spte)) { clear_bit((ffs(shadow_accessed_mask) - 1), (unsigned long *)sptep); } else { /* * Capture the dirty status of the page, so that it doesn't get * lost when the SPTE is marked for access tracking. */ if (is_writable_pte(spte)) kvm_set_pfn_dirty(spte_to_pfn(spte)); spte = mark_spte_for_access_track(spte); mmu_spte_update_no_track(sptep, spte); } return true; } static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) { /* * Prevent page table teardown by making any free-er wait during * kvm_flush_remote_tlbs() IPI to all active vcpus. */ local_irq_disable(); /* * Make sure a following spte read is not reordered ahead of the write * to vcpu->mode. */ smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES); } static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) { /* * Make sure the write to vcpu->mode is not reordered in front of * reads to sptes. If it does, kvm_mmu_commit_zap_page() can see us * OUTSIDE_GUEST_MODE and proceed to free the shadow page table. */ smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE); local_irq_enable(); } static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) { int r; /* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */ r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache, 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM); if (r) return r; r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache, PT64_ROOT_MAX_LEVEL); if (r) return r; if (maybe_indirect) { r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache, PT64_ROOT_MAX_LEVEL); if (r) return r; } return kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, PT64_ROOT_MAX_LEVEL); } static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) { kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_gfn_array_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache); } static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu) { return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache); } static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc) { kmem_cache_free(pte_list_desc_cache, pte_list_desc); } static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index) { if (!sp->role.direct) return sp->gfns[index]; return sp->gfn + (index << ((sp->role.level - 1) * PT64_LEVEL_BITS)); } static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, int index, gfn_t gfn) { if (!sp->role.direct) { sp->gfns[index] = gfn; return; } if (WARN_ON(gfn != kvm_mmu_page_get_gfn(sp, index))) pr_err_ratelimited("gfn mismatch under direct page %llx " "(expected %llx, got %llx)\n", sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn); } /* * Return the pointer to the large page information for a given gfn, * handling slots that are not large page aligned. */ static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn, const struct kvm_memory_slot *slot, int level) { unsigned long idx; idx = gfn_to_index(gfn, slot->base_gfn, level); return &slot->arch.lpage_info[level - 2][idx]; } static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot, gfn_t gfn, int count) { struct kvm_lpage_info *linfo; int i; for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { linfo = lpage_info_slot(gfn, slot, i); linfo->disallow_lpage += count; WARN_ON(linfo->disallow_lpage < 0); } } void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn) { update_gfn_disallow_lpage_count(slot, gfn, 1); } void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn) { update_gfn_disallow_lpage_count(slot, gfn, -1); } static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) { struct kvm_memslots *slots; struct kvm_memory_slot *slot; gfn_t gfn; kvm->arch.indirect_shadow_pages++; gfn = sp->gfn; slots = kvm_memslots_for_spte_role(kvm, sp->role); slot = __gfn_to_memslot(slots, gfn); /* the non-leaf shadow pages are keeping readonly. */ if (sp->role.level > PG_LEVEL_4K) return kvm_slot_page_track_add_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); kvm_mmu_gfn_disallow_lpage(slot, gfn); } void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) { if (sp->lpage_disallowed) return; ++kvm->stat.nx_lpage_splits; list_add_tail(&sp->lpage_disallowed_link, &kvm->arch.lpage_disallowed_mmu_pages); sp->lpage_disallowed = true; } static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) { struct kvm_memslots *slots; struct kvm_memory_slot *slot; gfn_t gfn; kvm->arch.indirect_shadow_pages--; gfn = sp->gfn; slots = kvm_memslots_for_spte_role(kvm, sp->role); slot = __gfn_to_memslot(slots, gfn); if (sp->role.level > PG_LEVEL_4K) return kvm_slot_page_track_remove_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); kvm_mmu_gfn_allow_lpage(slot, gfn); } void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) { --kvm->stat.nx_lpage_splits; sp->lpage_disallowed = false; list_del(&sp->lpage_disallowed_link); } static struct kvm_memory_slot * gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, bool no_dirty_log) { struct kvm_memory_slot *slot; slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); if (!slot || slot->flags & KVM_MEMSLOT_INVALID) return NULL; if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) return NULL; return slot; } /* * About rmap_head encoding: * * If the bit zero of rmap_head->val is clear, then it points to the only spte * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct * pte_list_desc containing more mappings. */ /* * Returns the number of pointers in the rmap chain, not counting the new one. */ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte, struct kvm_rmap_head *rmap_head) { struct pte_list_desc *desc; int i, count = 0; if (!rmap_head->val) { rmap_printk("%p %llx 0->1\n", spte, *spte); rmap_head->val = (unsigned long)spte; } else if (!(rmap_head->val & 1)) { rmap_printk("%p %llx 1->many\n", spte, *spte); desc = mmu_alloc_pte_list_desc(vcpu); desc->sptes[0] = (u64 *)rmap_head->val; desc->sptes[1] = spte; rmap_head->val = (unsigned long)desc | 1; ++count; } else { rmap_printk("%p %llx many->many\n", spte, *spte); desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); while (desc->sptes[PTE_LIST_EXT-1]) { count += PTE_LIST_EXT; if (!desc->more) { desc->more = mmu_alloc_pte_list_desc(vcpu); desc = desc->more; break; } desc = desc->more; } for (i = 0; desc->sptes[i]; ++i) ++count; desc->sptes[i] = spte; } return count; } static void pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head, struct pte_list_desc *desc, int i, struct pte_list_desc *prev_desc) { int j; for (j = PTE_LIST_EXT - 1; !desc->sptes[j] && j > i; --j) ; desc->sptes[i] = desc->sptes[j]; desc->sptes[j] = NULL; if (j != 0) return; if (!prev_desc && !desc->more) rmap_head->val = 0; else if (prev_desc) prev_desc->more = desc->more; else rmap_head->val = (unsigned long)desc->more | 1; mmu_free_pte_list_desc(desc); } static void __pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head) { struct pte_list_desc *desc; struct pte_list_desc *prev_desc; int i; if (!rmap_head->val) { pr_err("%s: %p 0->BUG\n", __func__, spte); BUG(); } else if (!(rmap_head->val & 1)) { rmap_printk("%p 1->0\n", spte); if ((u64 *)rmap_head->val != spte) { pr_err("%s: %p 1->BUG\n", __func__, spte); BUG(); } rmap_head->val = 0; } else { rmap_printk("%p many->many\n", spte); desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); prev_desc = NULL; while (desc) { for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i) { if (desc->sptes[i] == spte) { pte_list_desc_remove_entry(rmap_head, desc, i, prev_desc); return; } } prev_desc = desc; desc = desc->more; } pr_err("%s: %p many->many\n", __func__, spte); BUG(); } } static void pte_list_remove(struct kvm_rmap_head *rmap_head, u64 *sptep) { mmu_spte_clear_track_bits(sptep); __pte_list_remove(sptep, rmap_head); } static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level, struct kvm_memory_slot *slot) { unsigned long idx; idx = gfn_to_index(gfn, slot->base_gfn, level); return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; } static struct kvm_rmap_head *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, struct kvm_mmu_page *sp) { struct kvm_memslots *slots; struct kvm_memory_slot *slot; slots = kvm_memslots_for_spte_role(kvm, sp->role); slot = __gfn_to_memslot(slots, gfn); return __gfn_to_rmap(gfn, sp->role.level, slot); } static bool rmap_can_add(struct kvm_vcpu *vcpu) { struct kvm_mmu_memory_cache *mc; mc = &vcpu->arch.mmu_pte_list_desc_cache; return kvm_mmu_memory_cache_nr_free_objects(mc); } static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) { struct kvm_mmu_page *sp; struct kvm_rmap_head *rmap_head; sp = sptep_to_sp(spte); kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn); rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp); return pte_list_add(vcpu, spte, rmap_head); } static void rmap_remove(struct kvm *kvm, u64 *spte) { struct kvm_mmu_page *sp; gfn_t gfn; struct kvm_rmap_head *rmap_head; sp = sptep_to_sp(spte); gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt); rmap_head = gfn_to_rmap(kvm, gfn, sp); __pte_list_remove(spte, rmap_head); } /* * Used by the following functions to iterate through the sptes linked by a * rmap. All fields are private and not assumed to be used outside. */ struct rmap_iterator { /* private fields */ struct pte_list_desc *desc; /* holds the sptep if not NULL */ int pos; /* index of the sptep */ }; /* * Iteration must be started by this function. This should also be used after * removing/dropping sptes from the rmap link because in such cases the * information in the iterator may not be valid. * * Returns sptep if found, NULL otherwise. */ static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, struct rmap_iterator *iter) { u64 *sptep; if (!rmap_head->val) return NULL; if (!(rmap_head->val & 1)) { iter->desc = NULL; sptep = (u64 *)rmap_head->val; goto out; } iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); iter->pos = 0; sptep = iter->desc->sptes[iter->pos]; out: BUG_ON(!is_shadow_present_pte(*sptep)); return sptep; } /* * Must be used with a valid iterator: e.g. after rmap_get_first(). * * Returns sptep if found, NULL otherwise. */ static u64 *rmap_get_next(struct rmap_iterator *iter) { u64 *sptep; if (iter->desc) { if (iter->pos < PTE_LIST_EXT - 1) { ++iter->pos; sptep = iter->desc->sptes[iter->pos]; if (sptep) goto out; } iter->desc = iter->desc->more; if (iter->desc) { iter->pos = 0; /* desc->sptes[0] cannot be NULL */ sptep = iter->desc->sptes[iter->pos]; goto out; } } return NULL; out: BUG_ON(!is_shadow_present_pte(*sptep)); return sptep; } #define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \ for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \ _spte_; _spte_ = rmap_get_next(_iter_)) static void drop_spte(struct kvm *kvm, u64 *sptep) { if (mmu_spte_clear_track_bits(sptep)) rmap_remove(kvm, sptep); } static bool __drop_large_spte(struct kvm *kvm, u64 *sptep) { if (is_large_pte(*sptep)) { WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K); drop_spte(kvm, sptep); --kvm->stat.lpages; return true; } return false; } static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep) { if (__drop_large_spte(vcpu->kvm, sptep)) { struct kvm_mmu_page *sp = sptep_to_sp(sptep); kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); } } /* * Write-protect on the specified @sptep, @pt_protect indicates whether * spte write-protection is caused by protecting shadow page table. * * Note: write protection is difference between dirty logging and spte * protection: * - for dirty logging, the spte can be set to writable at anytime if * its dirty bitmap is properly set. * - for spte protection, the spte can be writable only after unsync-ing * shadow page. * * Return true if tlb need be flushed. */ static bool spte_write_protect(u64 *sptep, bool pt_protect) { u64 spte = *sptep; if (!is_writable_pte(spte) && !(pt_protect && spte_can_locklessly_be_made_writable(spte))) return false; rmap_printk("spte %p %llx\n", sptep, *sptep); if (pt_protect) spte &= ~shadow_mmu_writable_mask; spte = spte & ~PT_WRITABLE_MASK; return mmu_spte_update(sptep, spte); } static bool __rmap_write_protect(struct kvm *kvm, struct kvm_rmap_head *rmap_head, bool pt_protect) { u64 *sptep; struct rmap_iterator iter; bool flush = false; for_each_rmap_spte(rmap_head, &iter, sptep) flush |= spte_write_protect(sptep, pt_protect); return flush; } static bool spte_clear_dirty(u64 *sptep) { u64 spte = *sptep; rmap_printk("spte %p %llx\n", sptep, *sptep); MMU_WARN_ON(!spte_ad_enabled(spte)); spte &= ~shadow_dirty_mask; return mmu_spte_update(sptep, spte); } static bool spte_wrprot_for_clear_dirty(u64 *sptep) { bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, (unsigned long *)sptep); if (was_writable && !spte_ad_enabled(*sptep)) kvm_set_pfn_dirty(spte_to_pfn(*sptep)); return was_writable; } /* * Gets the GFN ready for another round of dirty logging by clearing the * - D bit on ad-enabled SPTEs, and * - W bit on ad-disabled SPTEs. * Returns true iff any D or W bits were cleared. */ static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot) { u64 *sptep; struct rmap_iterator iter; bool flush = false; for_each_rmap_spte(rmap_head, &iter, sptep) if (spte_ad_need_write_protect(*sptep)) flush |= spte_wrprot_for_clear_dirty(sptep); else flush |= spte_clear_dirty(sptep); return flush; } /** * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages * @kvm: kvm instance * @slot: slot to protect * @gfn_offset: start of the BITS_PER_LONG pages we care about * @mask: indicates which pages we should protect * * Used when we do not need to care about huge page mappings: e.g. during dirty * logging we do not have any such mappings. */ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { struct kvm_rmap_head *rmap_head; if (is_tdp_mmu_enabled(kvm)) kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, slot->base_gfn + gfn_offset, mask, true); while (mask) { rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PG_LEVEL_4K, slot); __rmap_write_protect(kvm, rmap_head, false); /* clear the first set bit */ mask &= mask - 1; } } /** * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write * protect the page if the D-bit isn't supported. * @kvm: kvm instance * @slot: slot to clear D-bit * @gfn_offset: start of the BITS_PER_LONG pages we care about * @mask: indicates which pages we should clear D-bit * * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. */ static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { struct kvm_rmap_head *rmap_head; if (is_tdp_mmu_enabled(kvm)) kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, slot->base_gfn + gfn_offset, mask, false); while (mask) { rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PG_LEVEL_4K, slot); __rmap_clear_dirty(kvm, rmap_head, slot); /* clear the first set bit */ mask &= mask - 1; } } /** * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected * PT level pages. * * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to * enable dirty logging for them. * * Used when we do not need to care about huge page mappings: e.g. during dirty * logging we do not have any such mappings. */ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { if (kvm_x86_ops.cpu_dirty_log_size) kvm_mmu_clear_dirty_pt_masked(kvm, slot, gfn_offset, mask); else kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask); } int kvm_cpu_dirty_log_size(void) { return kvm_x86_ops.cpu_dirty_log_size; } bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, struct kvm_memory_slot *slot, u64 gfn) { struct kvm_rmap_head *rmap_head; int i; bool write_protected = false; for (i = PG_LEVEL_4K; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { rmap_head = __gfn_to_rmap(gfn, i, slot); write_protected |= __rmap_write_protect(kvm, rmap_head, true); } if (is_tdp_mmu_enabled(kvm)) write_protected |= kvm_tdp_mmu_write_protect_gfn(kvm, slot, gfn); return write_protected; } static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn) { struct kvm_memory_slot *slot; slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); return kvm_mmu_slot_gfn_write_protect(vcpu->kvm, slot, gfn); } static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot) { u64 *sptep; struct rmap_iterator iter; bool flush = false; while ((sptep = rmap_get_first(rmap_head, &iter))) { rmap_printk("spte %p %llx.\n", sptep, *sptep); pte_list_remove(rmap_head, sptep); flush = true; } return flush; } static bool kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, pte_t unused) { return kvm_zap_rmapp(kvm, rmap_head, slot); } static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, pte_t pte) { u64 *sptep; struct rmap_iterator iter; int need_flush = 0; u64 new_spte; kvm_pfn_t new_pfn; WARN_ON(pte_huge(pte)); new_pfn = pte_pfn(pte); restart: for_each_rmap_spte(rmap_head, &iter, sptep) { rmap_printk("spte %p %llx gfn %llx (%d)\n", sptep, *sptep, gfn, level); need_flush = 1; if (pte_write(pte)) { pte_list_remove(rmap_head, sptep); goto restart; } else { new_spte = kvm_mmu_changed_pte_notifier_make_spte( *sptep, new_pfn); mmu_spte_clear_track_bits(sptep); mmu_spte_set(sptep, new_spte); } } if (need_flush && kvm_available_flush_tlb_with_range()) { kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); return 0; } return need_flush; } struct slot_rmap_walk_iterator { /* input fields. */ struct kvm_memory_slot *slot; gfn_t start_gfn; gfn_t end_gfn; int start_level; int end_level; /* output fields. */ gfn_t gfn; struct kvm_rmap_head *rmap; int level; /* private field. */ struct kvm_rmap_head *end_rmap; }; static void rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level) { iterator->level = level; iterator->gfn = iterator->start_gfn; iterator->rmap = __gfn_to_rmap(iterator->gfn, level, iterator->slot); iterator->end_rmap = __gfn_to_rmap(iterator->end_gfn, level, iterator->slot); } static void slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, struct kvm_memory_slot *slot, int start_level, int end_level, gfn_t start_gfn, gfn_t end_gfn) { iterator->slot = slot; iterator->start_level = start_level; iterator->end_level = end_level; iterator->start_gfn = start_gfn; iterator->end_gfn = end_gfn; rmap_walk_init_level(iterator, iterator->start_level); } static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) { return !!iterator->rmap; } static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) { if (++iterator->rmap <= iterator->end_rmap) { iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level)); return; } if (++iterator->level > iterator->end_level) { iterator->rmap = NULL; return; } rmap_walk_init_level(iterator, iterator->level); } #define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \ _start_gfn, _end_gfn, _iter_) \ for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \ _end_level_, _start_gfn, _end_gfn); \ slot_rmap_walk_okay(_iter_); \ slot_rmap_walk_next(_iter_)) typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, pte_t pte); static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, rmap_handler_t handler) { struct slot_rmap_walk_iterator iterator; bool ret = false; for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, range->start, range->end - 1, &iterator) ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn, iterator.level, range->pte); return ret; } bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) { bool flush; flush = kvm_handle_gfn_range(kvm, range, kvm_unmap_rmapp); if (is_tdp_mmu_enabled(kvm)) flush |= kvm_tdp_mmu_unmap_gfn_range(kvm, range, flush); return flush; } bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool flush; flush = kvm_handle_gfn_range(kvm, range, kvm_set_pte_rmapp); if (is_tdp_mmu_enabled(kvm)) flush |= kvm_tdp_mmu_set_spte_gfn(kvm, range); return flush; } static bool kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, pte_t unused) { u64 *sptep; struct rmap_iterator iter; int young = 0; for_each_rmap_spte(rmap_head, &iter, sptep) young |= mmu_spte_age(sptep); return young; } static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, pte_t unused) { u64 *sptep; struct rmap_iterator iter; for_each_rmap_spte(rmap_head, &iter, sptep) if (is_accessed_spte(*sptep)) return 1; return 0; } #define RMAP_RECYCLE_THRESHOLD 1000 static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) { struct kvm_rmap_head *rmap_head; struct kvm_mmu_page *sp; sp = sptep_to_sp(spte); rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp); kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0)); kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); } bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young; young = kvm_handle_gfn_range(kvm, range, kvm_age_rmapp); if (is_tdp_mmu_enabled(kvm)) young |= kvm_tdp_mmu_age_gfn_range(kvm, range); return young; } bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young; young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmapp); if (is_tdp_mmu_enabled(kvm)) young |= kvm_tdp_mmu_test_age_gfn(kvm, range); return young; } #ifdef MMU_DEBUG static int is_empty_shadow_page(u64 *spt) { u64 *pos; u64 *end; for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++) if (is_shadow_present_pte(*pos)) { printk(KERN_ERR "%s: %p %llx\n", __func__, pos, *pos); return 0; } return 1; } #endif /* * This value is the sum of all of the kvm instances's * kvm->arch.n_used_mmu_pages values. We need a global, * aggregate version in order to make the slab shrinker * faster */ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, unsigned long nr) { kvm->arch.n_used_mmu_pages += nr; percpu_counter_add(&kvm_total_used_mmu_pages, nr); } static void kvm_mmu_free_page(struct kvm_mmu_page *sp) { MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); hlist_del(&sp->hash_link); list_del(&sp->link); free_page((unsigned long)sp->spt); if (!sp->role.direct) free_page((unsigned long)sp->gfns); kmem_cache_free(mmu_page_header_cache, sp); } static unsigned kvm_page_table_hashfn(gfn_t gfn) { return hash_64(gfn, KVM_MMU_HASH_SHIFT); } static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *parent_pte) { if (!parent_pte) return; pte_list_add(vcpu, parent_pte, &sp->parent_ptes); } static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, u64 *parent_pte) { __pte_list_remove(parent_pte, &sp->parent_ptes); } static void drop_parent_pte(struct kvm_mmu_page *sp, u64 *parent_pte) { mmu_page_remove_parent_pte(sp, parent_pte); mmu_spte_clear_no_track(parent_pte); } static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct) { struct kvm_mmu_page *sp; sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache); sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache); if (!direct) sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache); set_page_private(virt_to_page(sp->spt), (unsigned long)sp); /* * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() * depends on valid pages being added to the head of the list. See * comments in kvm_zap_obsolete_pages(). */ sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen; list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages); kvm_mod_used_mmu_pages(vcpu->kvm, +1); return sp; } static void mark_unsync(u64 *spte); static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) { u64 *sptep; struct rmap_iterator iter; for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) { mark_unsync(sptep); } } static void mark_unsync(u64 *spte) { struct kvm_mmu_page *sp; unsigned int index; sp = sptep_to_sp(spte); index = spte - sp->spt; if (__test_and_set_bit(index, sp->unsync_child_bitmap)) return; if (sp->unsync_children++) return; kvm_mmu_mark_parents_unsync(sp); } static int nonpaging_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) { return 0; } #define KVM_PAGE_ARRAY_NR 16 struct kvm_mmu_pages { struct mmu_page_and_offset { struct kvm_mmu_page *sp; unsigned int idx; } page[KVM_PAGE_ARRAY_NR]; unsigned int nr; }; static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, int idx) { int i; if (sp->unsync) for (i=0; i < pvec->nr; i++) if (pvec->page[i].sp == sp) return 0; pvec->page[pvec->nr].sp = sp; pvec->page[pvec->nr].idx = idx; pvec->nr++; return (pvec->nr == KVM_PAGE_ARRAY_NR); } static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) { --sp->unsync_children; WARN_ON((int)sp->unsync_children < 0); __clear_bit(idx, sp->unsync_child_bitmap); } static int __mmu_unsync_walk(struct kvm_mmu_page *sp, struct kvm_mmu_pages *pvec) { int i, ret, nr_unsync_leaf = 0; for_each_set_bit(i, sp->unsync_child_bitmap, 512) { struct kvm_mmu_page *child; u64 ent = sp->spt[i]; if (!is_shadow_present_pte(ent) || is_large_pte(ent)) { clear_unsync_child_bit(sp, i); continue; } child = to_shadow_page(ent & PT64_BASE_ADDR_MASK); if (child->unsync_children) { if (mmu_pages_add(pvec, child, i)) return -ENOSPC; ret = __mmu_unsync_walk(child, pvec); if (!ret) { clear_unsync_child_bit(sp, i); continue; } else if (ret > 0) { nr_unsync_leaf += ret; } else return ret; } else if (child->unsync) { nr_unsync_leaf++; if (mmu_pages_add(pvec, child, i)) return -ENOSPC; } else clear_unsync_child_bit(sp, i); } return nr_unsync_leaf; } #define INVALID_INDEX (-1) static int mmu_unsync_walk(struct kvm_mmu_page *sp, struct kvm_mmu_pages *pvec) { pvec->nr = 0; if (!sp->unsync_children) return 0; mmu_pages_add(pvec, sp, INVALID_INDEX); return __mmu_unsync_walk(sp, pvec); } static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) { WARN_ON(!sp->unsync); trace_kvm_mmu_sync_page(sp); sp->unsync = 0; --kvm->stat.mmu_unsync; } static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, struct list_head *invalid_list); static void kvm_mmu_commit_zap_page(struct kvm *kvm, struct list_head *invalid_list); #define for_each_valid_sp(_kvm, _sp, _list) \ hlist_for_each_entry(_sp, _list, hash_link) \ if (is_obsolete_sp((_kvm), (_sp))) { \ } else #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ for_each_valid_sp(_kvm, _sp, \ &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else static inline bool is_ept_sp(struct kvm_mmu_page *sp) { return sp->role.cr0_wp && sp->role.smap_andnot_wp; } /* @sp->gfn should be write-protected at the call site */ static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, struct list_head *invalid_list) { if ((!is_ept_sp(sp) && sp->role.gpte_is_8_bytes != !!is_pae(vcpu)) || vcpu->arch.mmu->sync_page(vcpu, sp) == 0) { kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); return false; } return true; } static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, struct list_head *invalid_list, bool remote_flush) { if (!remote_flush && list_empty(invalid_list)) return false; if (!list_empty(invalid_list)) kvm_mmu_commit_zap_page(kvm, invalid_list); else kvm_flush_remote_tlbs(kvm); return true; } static void kvm_mmu_flush_or_zap(struct kvm_vcpu *vcpu, struct list_head *invalid_list, bool remote_flush, bool local_flush) { if (kvm_mmu_remote_flush_or_zap(vcpu->kvm, invalid_list, remote_flush)) return; if (local_flush) kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); } #ifdef CONFIG_KVM_MMU_AUDIT #include "mmu_audit.c" #else static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { } static void mmu_audit_disable(void) { } #endif static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) { return sp->role.invalid || unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); } static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, struct list_head *invalid_list) { kvm_unlink_unsync_page(vcpu->kvm, sp); return __kvm_sync_page(vcpu, sp, invalid_list); } /* @gfn should be write-protected at the call site */ static bool kvm_sync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, struct list_head *invalid_list) { struct kvm_mmu_page *s; bool ret = false; for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) { if (!s->unsync) continue; WARN_ON(s->role.level != PG_LEVEL_4K); ret |= kvm_sync_page(vcpu, s, invalid_list); } return ret; } struct mmu_page_path { struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL]; unsigned int idx[PT64_ROOT_MAX_LEVEL]; }; #define for_each_sp(pvec, sp, parents, i) \ for (i = mmu_pages_first(&pvec, &parents); \ i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \ i = mmu_pages_next(&pvec, &parents, i)) static int mmu_pages_next(struct kvm_mmu_pages *pvec, struct mmu_page_path *parents, int i) { int n; for (n = i+1; n < pvec->nr; n++) { struct kvm_mmu_page *sp = pvec->page[n].sp; unsigned idx = pvec->page[n].idx; int level = sp->role.level; parents->idx[level-1] = idx; if (level == PG_LEVEL_4K) break; parents->parent[level-2] = sp; } return n; } static int mmu_pages_first(struct kvm_mmu_pages *pvec, struct mmu_page_path *parents) { struct kvm_mmu_page *sp; int level; if (pvec->nr == 0) return 0; WARN_ON(pvec->page[0].idx != INVALID_INDEX); sp = pvec->page[0].sp; level = sp->role.level; WARN_ON(level == PG_LEVEL_4K); parents->parent[level-2] = sp; /* Also set up a sentinel. Further entries in pvec are all * children of sp, so this element is never overwritten. */ parents->parent[level-1] = NULL; return mmu_pages_next(pvec, parents, 0); } static void mmu_pages_clear_parents(struct mmu_page_path *parents) { struct kvm_mmu_page *sp; unsigned int level = 0; do { unsigned int idx = parents->idx[level]; sp = parents->parent[level]; if (!sp) return; WARN_ON(idx == INVALID_INDEX); clear_unsync_child_bit(sp, idx); level++; } while (!sp->unsync_children); } static void mmu_sync_children(struct kvm_vcpu *vcpu, struct kvm_mmu_page *parent) { int i; struct kvm_mmu_page *sp; struct mmu_page_path parents; struct kvm_mmu_pages pages; LIST_HEAD(invalid_list); bool flush = false; while (mmu_unsync_walk(parent, &pages)) { bool protected = false; for_each_sp(pages, sp, parents, i) protected |= rmap_write_protect(vcpu, sp->gfn); if (protected) { kvm_flush_remote_tlbs(vcpu->kvm); flush = false; } for_each_sp(pages, sp, parents, i) { flush |= kvm_sync_page(vcpu, sp, &invalid_list); mmu_pages_clear_parents(&parents); } if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) { kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); cond_resched_rwlock_write(&vcpu->kvm->mmu_lock); flush = false; } } kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); } static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) { atomic_set(&sp->write_flooding_count, 0); } static void clear_sp_write_flooding_count(u64 *spte) { __clear_sp_write_flooding_count(sptep_to_sp(spte)); } static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gaddr, unsigned level, int direct, unsigned int access) { bool direct_mmu = vcpu->arch.mmu->direct_map; union kvm_mmu_page_role role; struct hlist_head *sp_list; unsigned quadrant; struct kvm_mmu_page *sp; bool need_sync = false; bool flush = false; int collisions = 0; LIST_HEAD(invalid_list); role = vcpu->arch.mmu->mmu_role.base; role.level = level; role.direct = direct; if (role.direct) role.gpte_is_8_bytes = true; role.access = access; if (!direct_mmu && vcpu->arch.mmu->root_level <= PT32_ROOT_LEVEL) { quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level)); quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1; role.quadrant = quadrant; } sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; for_each_valid_sp(vcpu->kvm, sp, sp_list) { if (sp->gfn != gfn) { collisions++; continue; } if (!need_sync && sp->unsync) need_sync = true; if (sp->role.word != role.word) continue; if (direct_mmu) goto trace_get_page; if (sp->unsync) { /* The page is good, but __kvm_sync_page might still end * up zapping it. If so, break in order to rebuild it. */ if (!__kvm_sync_page(vcpu, sp, &invalid_list)) break; WARN_ON(!list_empty(&invalid_list)); kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); } if (sp->unsync_children) kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); __clear_sp_write_flooding_count(sp); trace_get_page: trace_kvm_mmu_get_page(sp, false); goto out; } ++vcpu->kvm->stat.mmu_cache_miss; sp = kvm_mmu_alloc_page(vcpu, direct); sp->gfn = gfn; sp->role = role; hlist_add_head(&sp->hash_link, sp_list); if (!direct) { /* * we should do write protection before syncing pages * otherwise the content of the synced shadow page may * be inconsistent with guest page table. */ account_shadowed(vcpu->kvm, sp); if (level == PG_LEVEL_4K && rmap_write_protect(vcpu, gfn)) kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1); if (level > PG_LEVEL_4K && need_sync) flush |= kvm_sync_pages(vcpu, gfn, &invalid_list); } trace_kvm_mmu_get_page(sp, true); kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); out: if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions) vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions; return sp; } static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, struct kvm_vcpu *vcpu, hpa_t root, u64 addr) { iterator->addr = addr; iterator->shadow_addr = root; iterator->level = vcpu->arch.mmu->shadow_root_level; if (iterator->level == PT64_ROOT_4LEVEL && vcpu->arch.mmu->root_level < PT64_ROOT_4LEVEL && !vcpu->arch.mmu->direct_map) --iterator->level; if (iterator->level == PT32E_ROOT_LEVEL) { /* * prev_root is currently only used for 64-bit hosts. So only * the active root_hpa is valid here. */ BUG_ON(root != vcpu->arch.mmu->root_hpa); iterator->shadow_addr = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; iterator->shadow_addr &= PT64_BASE_ADDR_MASK; --iterator->level; if (!iterator->shadow_addr) iterator->level = 0; } } static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, struct kvm_vcpu *vcpu, u64 addr) { shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu->root_hpa, addr); } static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) { if (iterator->level < PG_LEVEL_4K) return false; iterator->index = SHADOW_PT_INDEX(iterator->addr, iterator->level); iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; return true; } static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, u64 spte) { if (is_last_spte(spte, iterator->level)) { iterator->level = 0; return; } iterator->shadow_addr = spte & PT64_BASE_ADDR_MASK; --iterator->level; } static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) { __shadow_walk_next(iterator, *iterator->sptep); } static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, struct kvm_mmu_page *sp) { u64 spte; BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp)); mmu_spte_set(sptep, spte); mmu_page_add_parent_pte(vcpu, sp, sptep); if (sp->unsync_children || sp->unsync) mark_unsync(sptep); } static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned direct_access) { if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { struct kvm_mmu_page *child; /* * For the direct sp, if the guest pte's dirty bit * changed form clean to dirty, it will corrupt the * sp's access: allow writable in the read-only sp, * so we should update the spte at this point to get * a new sp with the correct access. */ child = to_shadow_page(*sptep & PT64_BASE_ADDR_MASK); if (child->role.access == direct_access) return; drop_parent_pte(child, sptep); kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1); } } /* Returns the number of zapped non-leaf child shadow pages. */ static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *spte, struct list_head *invalid_list) { u64 pte; struct kvm_mmu_page *child; pte = *spte; if (is_shadow_present_pte(pte)) { if (is_last_spte(pte, sp->role.level)) { drop_spte(kvm, spte); if (is_large_pte(pte)) --kvm->stat.lpages; } else { child = to_shadow_page(pte & PT64_BASE_ADDR_MASK); drop_parent_pte(child, spte); /* * Recursively zap nested TDP SPs, parentless SPs are * unlikely to be used again in the near future. This * avoids retaining a large number of stale nested SPs. */ if (tdp_enabled && invalid_list && child->role.guest_mode && !child->parent_ptes.val) return kvm_mmu_prepare_zap_page(kvm, child, invalid_list); } } else if (is_mmio_spte(pte)) { mmu_spte_clear_no_track(spte); } return 0; } static int kvm_mmu_page_unlink_children(struct kvm *kvm, struct kvm_mmu_page *sp, struct list_head *invalid_list) { int zapped = 0; unsigned i; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) zapped += mmu_page_zap_pte(kvm, sp, sp->spt + i, invalid_list); return zapped; } static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp) { u64 *sptep; struct rmap_iterator iter; while ((sptep = rmap_get_first(&sp->parent_ptes, &iter))) drop_parent_pte(sp, sptep); } static int mmu_zap_unsync_children(struct kvm *kvm, struct kvm_mmu_page *parent, struct list_head *invalid_list) { int i, zapped = 0; struct mmu_page_path parents; struct kvm_mmu_pages pages; if (parent->role.level == PG_LEVEL_4K) return 0; while (mmu_unsync_walk(parent, &pages)) { struct kvm_mmu_page *sp; for_each_sp(pages, sp, parents, i) { kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); mmu_pages_clear_parents(&parents); zapped++; } } return zapped; } static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, struct list_head *invalid_list, int *nr_zapped) { bool list_unstable; trace_kvm_mmu_prepare_zap_page(sp); ++kvm->stat.mmu_shadow_zapped; *nr_zapped = mmu_zap_unsync_children(kvm, sp, invalid_list); *nr_zapped += kvm_mmu_page_unlink_children(kvm, sp, invalid_list); kvm_mmu_unlink_parents(kvm, sp); /* Zapping children means active_mmu_pages has become unstable. */ list_unstable = *nr_zapped; if (!sp->role.invalid && !sp->role.direct) unaccount_shadowed(kvm, sp); if (sp->unsync) kvm_unlink_unsync_page(kvm, sp); if (!sp->root_count) { /* Count self */ (*nr_zapped)++; /* * Already invalid pages (previously active roots) are not on * the active page list. See list_del() in the "else" case of * !sp->root_count. */ if (sp->role.invalid) list_add(&sp->link, invalid_list); else list_move(&sp->link, invalid_list); kvm_mod_used_mmu_pages(kvm, -1); } else { /* * Remove the active root from the active page list, the root * will be explicitly freed when the root_count hits zero. */ list_del(&sp->link); /* * Obsolete pages cannot be used on any vCPUs, see the comment * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also * treats invalid shadow pages as being obsolete. */ if (!is_obsolete_sp(kvm, sp)) kvm_reload_remote_mmus(kvm); } if (sp->lpage_disallowed) unaccount_huge_nx_page(kvm, sp); sp->role.invalid = 1; return list_unstable; } static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, struct list_head *invalid_list) { int nr_zapped; __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list, &nr_zapped); return nr_zapped; } static void kvm_mmu_commit_zap_page(struct kvm *kvm, struct list_head *invalid_list) { struct kvm_mmu_page *sp, *nsp; if (list_empty(invalid_list)) return; /* * We need to make sure everyone sees our modifications to * the page tables and see changes to vcpu->mode here. The barrier * in the kvm_flush_remote_tlbs() achieves this. This pairs * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end. * * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit * guest mode and/or lockless shadow page table walks. */ kvm_flush_remote_tlbs(kvm); list_for_each_entry_safe(sp, nsp, invalid_list, link) { WARN_ON(!sp->role.invalid || sp->root_count); kvm_mmu_free_page(sp); } } static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, unsigned long nr_to_zap) { unsigned long total_zapped = 0; struct kvm_mmu_page *sp, *tmp; LIST_HEAD(invalid_list); bool unstable; int nr_zapped; if (list_empty(&kvm->arch.active_mmu_pages)) return 0; restart: list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { /* * Don't zap active root pages, the page itself can't be freed * and zapping it will just force vCPUs to realloc and reload. */ if (sp->root_count) continue; unstable = __kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &nr_zapped); total_zapped += nr_zapped; if (total_zapped >= nr_to_zap) break; if (unstable) goto restart; } kvm_mmu_commit_zap_page(kvm, &invalid_list); kvm->stat.mmu_recycled += total_zapped; return total_zapped; } static inline unsigned long kvm_mmu_available_pages(struct kvm *kvm) { if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) return kvm->arch.n_max_mmu_pages - kvm->arch.n_used_mmu_pages; return 0; } static int make_mmu_pages_available(struct kvm_vcpu *vcpu) { unsigned long avail = kvm_mmu_available_pages(vcpu->kvm); if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) return 0; kvm_mmu_zap_oldest_mmu_pages(vcpu->kvm, KVM_REFILL_PAGES - avail); /* * Note, this check is intentionally soft, it only guarantees that one * page is available, while the caller may end up allocating as many as * four pages, e.g. for PAE roots or for 5-level paging. Temporarily * exceeding the (arbitrary by default) limit will not harm the host, * being too agressive may unnecessarily kill the guest, and getting an * exact count is far more trouble than it's worth, especially in the * page fault paths. */ if (!kvm_mmu_available_pages(vcpu->kvm)) return -ENOSPC; return 0; } /* * Changing the number of mmu pages allocated to the vm * Note: if goal_nr_mmu_pages is too small, you will get dead lock */ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) { write_lock(&kvm->mmu_lock); if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages - goal_nr_mmu_pages); goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; } kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; write_unlock(&kvm->mmu_lock); } int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) { struct kvm_mmu_page *sp; LIST_HEAD(invalid_list); int r; pgprintk("%s: looking for gfn %llx\n", __func__, gfn); r = 0; write_lock(&kvm->mmu_lock); for_each_gfn_indirect_valid_sp(kvm, sp, gfn) { pgprintk("%s: gfn %llx role %x\n", __func__, gfn, sp->role.word); r = 1; kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); } kvm_mmu_commit_zap_page(kvm, &invalid_list); write_unlock(&kvm->mmu_lock); return r; } static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) { gpa_t gpa; int r; if (vcpu->arch.mmu->direct_map) return 0; gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL); r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT); return r; } static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) { trace_kvm_mmu_unsync_page(sp); ++vcpu->kvm->stat.mmu_unsync; sp->unsync = 1; kvm_mmu_mark_parents_unsync(sp); } bool mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync) { struct kvm_mmu_page *sp; if (kvm_page_track_is_active(vcpu, gfn, KVM_PAGE_TRACK_WRITE)) return true; for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) { if (!can_unsync) return true; if (sp->unsync) continue; WARN_ON(sp->role.level != PG_LEVEL_4K); kvm_unsync_page(vcpu, sp); } /* * We need to ensure that the marking of unsync pages is visible * before the SPTE is updated to allow writes because * kvm_mmu_sync_roots() checks the unsync flags without holding * the MMU lock and so can race with this. If the SPTE was updated * before the page had been marked as unsync-ed, something like the * following could happen: * * CPU 1 CPU 2 * --------------------------------------------------------------------- * 1.2 Host updates SPTE * to be writable * 2.1 Guest writes a GPTE for GVA X. * (GPTE being in the guest page table shadowed * by the SP from CPU 1.) * This reads SPTE during the page table walk. * Since SPTE.W is read as 1, there is no * fault. * * 2.2 Guest issues TLB flush. * That causes a VM Exit. * * 2.3 kvm_mmu_sync_pages() reads sp->unsync. * Since it is false, so it just returns. * * 2.4 Guest accesses GVA X. * Since the mapping in the SP was not updated, * so the old mapping for GVA X incorrectly * gets used. * 1.1 Host marks SP * as unsync * (sp->unsync = true) * * The write barrier below ensures that 1.1 happens before 1.2 and thus * the situation in 2.4 does not arise. The implicit barrier in 2.2 * pairs with this write barrier. */ smp_wmb(); return false; } static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned int pte_access, int level, gfn_t gfn, kvm_pfn_t pfn, bool speculative, bool can_unsync, bool host_writable) { u64 spte; struct kvm_mmu_page *sp; int ret; sp = sptep_to_sp(sptep); ret = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative, can_unsync, host_writable, sp_ad_disabled(sp), &spte); if (spte & PT_WRITABLE_MASK) kvm_vcpu_mark_page_dirty(vcpu, gfn); if (*sptep == spte) ret |= SET_SPTE_SPURIOUS; else if (mmu_spte_update(sptep, spte)) ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH; return ret; } static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned int pte_access, bool write_fault, int level, gfn_t gfn, kvm_pfn_t pfn, bool speculative, bool host_writable) { int was_rmapped = 0; int rmap_count; int set_spte_ret; int ret = RET_PF_FIXED; bool flush = false; pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, *sptep, write_fault, gfn); if (unlikely(is_noslot_pfn(pfn))) { mark_mmio_spte(vcpu, sptep, gfn, pte_access); return RET_PF_EMULATE; } if (is_shadow_present_pte(*sptep)) { /* * If we overwrite a PTE page pointer with a 2MB PMD, unlink * the parent of the now unreachable PTE. */ if (level > PG_LEVEL_4K && !is_large_pte(*sptep)) { struct kvm_mmu_page *child; u64 pte = *sptep; child = to_shadow_page(pte & PT64_BASE_ADDR_MASK); drop_parent_pte(child, sptep); flush = true; } else if (pfn != spte_to_pfn(*sptep)) { pgprintk("hfn old %llx new %llx\n", spte_to_pfn(*sptep), pfn); drop_spte(vcpu->kvm, sptep); flush = true; } else was_rmapped = 1; } set_spte_ret = set_spte(vcpu, sptep, pte_access, level, gfn, pfn, speculative, true, host_writable); if (set_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) { if (write_fault) ret = RET_PF_EMULATE; kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); } if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush) kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, KVM_PAGES_PER_HPAGE(level)); /* * The fault is fully spurious if and only if the new SPTE and old SPTE * are identical, and emulation is not required. */ if ((set_spte_ret & SET_SPTE_SPURIOUS) && ret == RET_PF_FIXED) { WARN_ON_ONCE(!was_rmapped); return RET_PF_SPURIOUS; } pgprintk("%s: setting spte %llx\n", __func__, *sptep); trace_kvm_mmu_set_spte(level, gfn, sptep); if (!was_rmapped && is_large_pte(*sptep)) ++vcpu->kvm->stat.lpages; if (is_shadow_present_pte(*sptep)) { if (!was_rmapped) { rmap_count = rmap_add(vcpu, sptep, gfn); if (rmap_count > RMAP_RECYCLE_THRESHOLD) rmap_recycle(vcpu, sptep, gfn); } } return ret; } static kvm_pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, bool no_dirty_log) { struct kvm_memory_slot *slot; slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, no_dirty_log); if (!slot) return KVM_PFN_ERR_FAULT; return gfn_to_pfn_memslot_atomic(slot, gfn); } static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *start, u64 *end) { struct page *pages[PTE_PREFETCH_NUM]; struct kvm_memory_slot *slot; unsigned int access = sp->role.access; int i, ret; gfn_t gfn; gfn = kvm_mmu_page_get_gfn(sp, start - sp->spt); slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); if (!slot) return -1; ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start); if (ret <= 0) return -1; for (i = 0; i < ret; i++, gfn++, start++) { mmu_set_spte(vcpu, start, access, false, sp->role.level, gfn, page_to_pfn(pages[i]), true, true); put_page(pages[i]); } return 0; } static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *sptep) { u64 *spte, *start = NULL; int i; WARN_ON(!sp->role.direct); i = (sptep - sp->spt) & ~(PTE_PREFETCH_NUM - 1); spte = sp->spt + i; for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { if (is_shadow_present_pte(*spte) || spte == sptep) { if (!start) continue; if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0) break; start = NULL; } else if (!start) start = spte; } } static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) { struct kvm_mmu_page *sp; sp = sptep_to_sp(sptep); /* * Without accessed bits, there's no way to distinguish between * actually accessed translations and prefetched, so disable pte * prefetch if accessed bits aren't available. */ if (sp_ad_disabled(sp)) return; if (sp->role.level > PG_LEVEL_4K) return; /* * If addresses are being invalidated, skip prefetching to avoid * accidentally prefetching those addresses. */ if (unlikely(vcpu->kvm->mmu_notifier_count)) return; __direct_pte_prefetch(vcpu, sp, sptep); } static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, const struct kvm_memory_slot *slot) { unsigned long hva; pte_t *pte; int level; if (!PageCompound(pfn_to_page(pfn)) && !kvm_is_zone_device_pfn(pfn)) return PG_LEVEL_4K; /* * Note, using the already-retrieved memslot and __gfn_to_hva_memslot() * is not solely for performance, it's also necessary to avoid the * "writable" check in __gfn_to_hva_many(), which will always fail on * read-only memslots due to gfn_to_hva() assuming writes. Earlier * page fault steps have already verified the guest isn't writing a * read-only memslot. */ hva = __gfn_to_hva_memslot(slot, gfn); pte = lookup_address_in_mm(kvm->mm, hva, &level); if (unlikely(!pte)) return PG_LEVEL_4K; return level; } int kvm_mmu_max_mapping_level(struct kvm *kvm, const struct kvm_memory_slot *slot, gfn_t gfn, kvm_pfn_t pfn, int max_level) { struct kvm_lpage_info *linfo; max_level = min(max_level, max_huge_page_level); for ( ; max_level > PG_LEVEL_4K; max_level--) { linfo = lpage_info_slot(gfn, slot, max_level); if (!linfo->disallow_lpage) break; } if (max_level == PG_LEVEL_4K) return PG_LEVEL_4K; return host_pfn_mapping_level(kvm, gfn, pfn, slot); } int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn, int max_level, kvm_pfn_t *pfnp, bool huge_page_disallowed, int *req_level) { struct kvm_memory_slot *slot; kvm_pfn_t pfn = *pfnp; kvm_pfn_t mask; int level; *req_level = PG_LEVEL_4K; if (unlikely(max_level == PG_LEVEL_4K)) return PG_LEVEL_4K; if (is_error_noslot_pfn(pfn) || kvm_is_reserved_pfn(pfn)) return PG_LEVEL_4K; slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, true); if (!slot) return PG_LEVEL_4K; level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, gfn, pfn, max_level); if (level == PG_LEVEL_4K) return level; *req_level = level = min(level, max_level); /* * Enforce the iTLB multihit workaround after capturing the requested * level, which will be used to do precise, accurate accounting. */ if (huge_page_disallowed) return PG_LEVEL_4K; /* * mmu_notifier_retry() was successful and mmu_lock is held, so * the pmd can't be split from under us. */ mask = KVM_PAGES_PER_HPAGE(level) - 1; VM_BUG_ON((gfn & mask) != (pfn & mask)); *pfnp = pfn & ~mask; return level; } void disallowed_hugepage_adjust(u64 spte, gfn_t gfn, int cur_level, kvm_pfn_t *pfnp, int *goal_levelp) { int level = *goal_levelp; if (cur_level == level && level > PG_LEVEL_4K && is_shadow_present_pte(spte) && !is_large_pte(spte)) { /* * A small SPTE exists for this pfn, but FNAME(fetch) * and __direct_map would like to create a large PTE * instead: just force them to go down another level, * patching back for them into pfn the next 9 bits of * the address. */ u64 page_mask = KVM_PAGES_PER_HPAGE(level) - KVM_PAGES_PER_HPAGE(level - 1); *pfnp |= gfn & page_mask; (*goal_levelp)--; } } static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, int map_writable, int max_level, kvm_pfn_t pfn, bool prefault, bool is_tdp) { bool nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(); bool write = error_code & PFERR_WRITE_MASK; bool exec = error_code & PFERR_FETCH_MASK; bool huge_page_disallowed = exec && nx_huge_page_workaround_enabled; struct kvm_shadow_walk_iterator it; struct kvm_mmu_page *sp; int level, req_level, ret; gfn_t gfn = gpa >> PAGE_SHIFT; gfn_t base_gfn = gfn; if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa))) return RET_PF_RETRY; level = kvm_mmu_hugepage_adjust(vcpu, gfn, max_level, &pfn, huge_page_disallowed, &req_level); trace_kvm_mmu_spte_requested(gpa, level, pfn); for_each_shadow_entry(vcpu, gpa, it) { /* * We cannot overwrite existing page tables with an NX * large page, as the leaf could be executable. */ if (nx_huge_page_workaround_enabled) disallowed_hugepage_adjust(*it.sptep, gfn, it.level, &pfn, &level); base_gfn = gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1); if (it.level == level) break; drop_large_spte(vcpu, it.sptep); if (!is_shadow_present_pte(*it.sptep)) { sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr, it.level - 1, true, ACC_ALL); link_shadow_page(vcpu, it.sptep, sp); if (is_tdp && huge_page_disallowed && req_level >= it.level) account_huge_nx_page(vcpu->kvm, sp); } } ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL, write, level, base_gfn, pfn, prefault, map_writable); if (ret == RET_PF_SPURIOUS) return ret; direct_pte_prefetch(vcpu, it.sptep); ++vcpu->stat.pf_fixed; return ret; } static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk) { send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, PAGE_SHIFT, tsk); } static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) { /* * Do not cache the mmio info caused by writing the readonly gfn * into the spte otherwise read access on readonly gfn also can * caused mmio page fault and treat it as mmio access. */ if (pfn == KVM_PFN_ERR_RO_FAULT) return RET_PF_EMULATE; if (pfn == KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current); return RET_PF_RETRY; } return -EFAULT; } static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, kvm_pfn_t pfn, unsigned int access, int *ret_val) { /* The pfn is invalid, report the error! */ if (unlikely(is_error_pfn(pfn))) { *ret_val = kvm_handle_bad_page(vcpu, gfn, pfn); return true; } if (unlikely(is_noslot_pfn(pfn))) { vcpu_cache_mmio_info(vcpu, gva, gfn, access & shadow_mmio_access_mask); /* * If MMIO caching is disabled, emulate immediately without * touching the shadow page tables as attempting to install an * MMIO SPTE will just be an expensive nop. */ if (unlikely(!shadow_mmio_value)) { *ret_val = RET_PF_EMULATE; return true; } } return false; } static bool page_fault_can_be_fast(u32 error_code) { /* * Do not fix the mmio spte with invalid generation number which * need to be updated by slow page fault path. */ if (unlikely(error_code & PFERR_RSVD_MASK)) return false; /* See if the page fault is due to an NX violation */ if (unlikely(((error_code & (PFERR_FETCH_MASK | PFERR_PRESENT_MASK)) == (PFERR_FETCH_MASK | PFERR_PRESENT_MASK)))) return false; /* * #PF can be fast if: * 1. The shadow page table entry is not present, which could mean that * the fault is potentially caused by access tracking (if enabled). * 2. The shadow page table entry is present and the fault * is caused by write-protect, that means we just need change the W * bit of the spte which can be done out of mmu-lock. * * However, if access tracking is disabled we know that a non-present * page must be a genuine page fault where we have to create a new SPTE. * So, if access tracking is disabled, we return true only for write * accesses to a present page. */ return shadow_acc_track_mask != 0 || ((error_code & (PFERR_WRITE_MASK | PFERR_PRESENT_MASK)) == (PFERR_WRITE_MASK | PFERR_PRESENT_MASK)); } /* * Returns true if the SPTE was fixed successfully. Otherwise, * someone else modified the SPTE from its original value. */ static bool fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *sptep, u64 old_spte, u64 new_spte) { gfn_t gfn; WARN_ON(!sp->role.direct); /* * Theoretically we could also set dirty bit (and flush TLB) here in * order to eliminate unnecessary PML logging. See comments in * set_spte. But fast_page_fault is very unlikely to happen with PML * enabled, so we do not do this. This might result in the same GPA * to be logged in PML buffer again when the write really happens, and * eventually to be called by mark_page_dirty twice. But it's also no * harm. This also avoids the TLB flush needed after setting dirty bit * so non-PML cases won't be impacted. * * Compare with set_spte where instead shadow_dirty_mask is set. */ if (cmpxchg64(sptep, old_spte, new_spte) != old_spte) return false; if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) { /* * The gfn of direct spte is stable since it is * calculated by sp->gfn. */ gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt); kvm_vcpu_mark_page_dirty(vcpu, gfn); } return true; } static bool is_access_allowed(u32 fault_err_code, u64 spte) { if (fault_err_code & PFERR_FETCH_MASK) return is_executable_pte(spte); if (fault_err_code & PFERR_WRITE_MASK) return is_writable_pte(spte); /* Fault was on Read access */ return spte & PT_PRESENT_MASK; } /* * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. */ static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u32 error_code) { struct kvm_shadow_walk_iterator iterator; struct kvm_mmu_page *sp; int ret = RET_PF_INVALID; u64 spte = 0ull; uint retry_count = 0; if (!page_fault_can_be_fast(error_code)) return ret; walk_shadow_page_lockless_begin(vcpu); do { u64 new_spte; for_each_shadow_entry_lockless(vcpu, cr2_or_gpa, iterator, spte) if (!is_shadow_present_pte(spte)) break; if (!is_shadow_present_pte(spte)) break; sp = sptep_to_sp(iterator.sptep); if (!is_last_spte(spte, sp->role.level)) break; /* * Check whether the memory access that caused the fault would * still cause it if it were to be performed right now. If not, * then this is a spurious fault caused by TLB lazily flushed, * or some other CPU has already fixed the PTE after the * current CPU took the fault. * * Need not check the access of upper level table entries since * they are always ACC_ALL. */ if (is_access_allowed(error_code, spte)) { ret = RET_PF_SPURIOUS; break; } new_spte = spte; if (is_access_track_spte(spte)) new_spte = restore_acc_track_spte(new_spte); /* * Currently, to simplify the code, write-protection can * be removed in the fast path only if the SPTE was * write-protected for dirty-logging or access tracking. */ if ((error_code & PFERR_WRITE_MASK) && spte_can_locklessly_be_made_writable(spte)) { new_spte |= PT_WRITABLE_MASK; /* * Do not fix write-permission on the large spte. Since * we only dirty the first page into the dirty-bitmap in * fast_pf_fix_direct_spte(), other pages are missed * if its slot has dirty logging enabled. * * Instead, we let the slow page fault path create a * normal spte to fix the access. * * See the comments in kvm_arch_commit_memory_region(). */ if (sp->role.level > PG_LEVEL_4K) break; } /* Verify that the fault can be handled in the fast path */ if (new_spte == spte || !is_access_allowed(error_code, new_spte)) break; /* * Currently, fast page fault only works for direct mapping * since the gfn is not stable for indirect shadow page. See * Documentation/virt/kvm/locking.rst to get more detail. */ if (fast_pf_fix_direct_spte(vcpu, sp, iterator.sptep, spte, new_spte)) { ret = RET_PF_FIXED; break; } if (++retry_count > 4) { printk_once(KERN_WARNING "kvm: Fast #PF retrying more than 4 times.\n"); break; } } while (true); trace_fast_page_fault(vcpu, cr2_or_gpa, error_code, iterator.sptep, spte, ret); walk_shadow_page_lockless_end(vcpu); return ret; } static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, struct list_head *invalid_list) { struct kvm_mmu_page *sp; if (!VALID_PAGE(*root_hpa)) return; sp = to_shadow_page(*root_hpa & PT64_BASE_ADDR_MASK); if (is_tdp_mmu_page(sp)) kvm_tdp_mmu_put_root(kvm, sp, false); else if (!--sp->root_count && sp->role.invalid) kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); *root_hpa = INVALID_PAGE; } /* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, ulong roots_to_free) { struct kvm *kvm = vcpu->kvm; int i; LIST_HEAD(invalid_list); bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT; BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); /* Before acquiring the MMU lock, see if we need to do any real work. */ if (!(free_active_root && VALID_PAGE(mmu->root_hpa))) { for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && VALID_PAGE(mmu->prev_roots[i].hpa)) break; if (i == KVM_MMU_NUM_PREV_ROOTS) return; } write_lock(&kvm->mmu_lock); for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa, &invalid_list); if (free_active_root) { if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL && (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) { mmu_free_root_page(kvm, &mmu->root_hpa, &invalid_list); } else if (mmu->pae_root) { for (i = 0; i < 4; ++i) { if (!IS_VALID_PAE_ROOT(mmu->pae_root[i])) continue; mmu_free_root_page(kvm, &mmu->pae_root[i], &invalid_list); mmu->pae_root[i] = INVALID_PAE_ROOT; } } mmu->root_hpa = INVALID_PAGE; mmu->root_pgd = 0; } kvm_mmu_commit_zap_page(kvm, &invalid_list); write_unlock(&kvm->mmu_lock); } EXPORT_SYMBOL_GPL(kvm_mmu_free_roots); static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn) { int ret = 0; if (!kvm_vcpu_is_visible_gfn(vcpu, root_gfn)) { kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); ret = 1; } return ret; } static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva, u8 level, bool direct) { struct kvm_mmu_page *sp; sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL); ++sp->root_count; return __pa(sp->spt); } static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; u8 shadow_root_level = mmu->shadow_root_level; hpa_t root; unsigned i; int r; write_lock(&vcpu->kvm->mmu_lock); r = make_mmu_pages_available(vcpu); if (r < 0) goto out_unlock; if (is_tdp_mmu_enabled(vcpu->kvm)) { root = kvm_tdp_mmu_get_vcpu_root_hpa(vcpu); mmu->root_hpa = root; } else if (shadow_root_level >= PT64_ROOT_4LEVEL) { root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level, true); mmu->root_hpa = root; } else if (shadow_root_level == PT32E_ROOT_LEVEL) { if (WARN_ON_ONCE(!mmu->pae_root)) { r = -EIO; goto out_unlock; } for (i = 0; i < 4; ++i) { WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i << 30, PT32_ROOT_LEVEL, true); mmu->pae_root[i] = root | PT_PRESENT_MASK | shadow_me_mask; } mmu->root_hpa = __pa(mmu->pae_root); } else { WARN_ONCE(1, "Bad TDP root level = %d\n", shadow_root_level); r = -EIO; goto out_unlock; } /* root_pgd is ignored for direct MMUs. */ mmu->root_pgd = 0; out_unlock: write_unlock(&vcpu->kvm->mmu_lock); return r; } static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; u64 pdptrs[4], pm_mask; gfn_t root_gfn, root_pgd; hpa_t root; unsigned i; int r; root_pgd = mmu->get_guest_pgd(vcpu); root_gfn = root_pgd >> PAGE_SHIFT; if (mmu_check_root(vcpu, root_gfn)) return 1; /* * On SVM, reading PDPTRs might access guest memory, which might fault * and thus might sleep. Grab the PDPTRs before acquiring mmu_lock. */ if (mmu->root_level == PT32E_ROOT_LEVEL) { for (i = 0; i < 4; ++i) { pdptrs[i] = mmu->get_pdptr(vcpu, i); if (!(pdptrs[i] & PT_PRESENT_MASK)) continue; if (mmu_check_root(vcpu, pdptrs[i] >> PAGE_SHIFT)) return 1; } } write_lock(&vcpu->kvm->mmu_lock); r = make_mmu_pages_available(vcpu); if (r < 0) goto out_unlock; /* * Do we shadow a long mode page table? If so we need to * write-protect the guests page table root. */ if (mmu->root_level >= PT64_ROOT_4LEVEL) { root = mmu_alloc_root(vcpu, root_gfn, 0, mmu->shadow_root_level, false); mmu->root_hpa = root; goto set_root_pgd; } if (WARN_ON_ONCE(!mmu->pae_root)) { r = -EIO; goto out_unlock; } /* * We shadow a 32 bit page table. This may be a legacy 2-level * or a PAE 3-level page table. In either case we need to be aware that * the shadow page table may be a PAE or a long mode page table. */ pm_mask = PT_PRESENT_MASK | shadow_me_mask; if (mmu->shadow_root_level == PT64_ROOT_4LEVEL) { pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; if (WARN_ON_ONCE(!mmu->pml4_root)) { r = -EIO; goto out_unlock; } mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask; } for (i = 0; i < 4; ++i) { WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); if (mmu->root_level == PT32E_ROOT_LEVEL) { if (!(pdptrs[i] & PT_PRESENT_MASK)) { mmu->pae_root[i] = INVALID_PAE_ROOT; continue; } root_gfn = pdptrs[i] >> PAGE_SHIFT; } root = mmu_alloc_root(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL, false); mmu->pae_root[i] = root | pm_mask; } if (mmu->shadow_root_level == PT64_ROOT_4LEVEL) mmu->root_hpa = __pa(mmu->pml4_root); else mmu->root_hpa = __pa(mmu->pae_root); set_root_pgd: mmu->root_pgd = root_pgd; out_unlock: write_unlock(&vcpu->kvm->mmu_lock); return 0; } static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; u64 *pml4_root, *pae_root; /* * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP * tables are allocated and initialized at root creation as there is no * equivalent level in the guest's NPT to shadow. Allocate the tables * on demand, as running a 32-bit L1 VMM on 64-bit KVM is very rare. */ if (mmu->direct_map || mmu->root_level >= PT64_ROOT_4LEVEL || mmu->shadow_root_level < PT64_ROOT_4LEVEL) return 0; /* * This mess only works with 4-level paging and needs to be updated to * work with 5-level paging. */ if (WARN_ON_ONCE(mmu->shadow_root_level != PT64_ROOT_4LEVEL)) return -EIO; if (mmu->pae_root && mmu->pml4_root) return 0; /* * The special roots should always be allocated in concert. Yell and * bail if KVM ends up in a state where only one of the roots is valid. */ if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root)) return -EIO; /* * Unlike 32-bit NPT, the PDP table doesn't need to be in low mem, and * doesn't need to be decrypted. */ pae_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); if (!pae_root) return -ENOMEM; pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); if (!pml4_root) { free_page((unsigned long)pae_root); return -ENOMEM; } mmu->pae_root = pae_root; mmu->pml4_root = pml4_root; return 0; } void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) { int i; struct kvm_mmu_page *sp; if (vcpu->arch.mmu->direct_map) return; if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) return; vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); if (vcpu->arch.mmu->root_level >= PT64_ROOT_4LEVEL) { hpa_t root = vcpu->arch.mmu->root_hpa; sp = to_shadow_page(root); /* * Even if another CPU was marking the SP as unsync-ed * simultaneously, any guest page table changes are not * guaranteed to be visible anyway until this VCPU issues a TLB * flush strictly after those changes are made. We only need to * ensure that the other CPU sets these flags before any actual * changes to the page tables are made. The comments in * mmu_need_write_protect() describe what could go wrong if this * requirement isn't satisfied. */ if (!smp_load_acquire(&sp->unsync) && !smp_load_acquire(&sp->unsync_children)) return; write_lock(&vcpu->kvm->mmu_lock); kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC); mmu_sync_children(vcpu, sp); kvm_mmu_audit(vcpu, AUDIT_POST_SYNC); write_unlock(&vcpu->kvm->mmu_lock); return; } write_lock(&vcpu->kvm->mmu_lock); kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC); for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu->pae_root[i]; if (IS_VALID_PAE_ROOT(root)) { root &= PT64_BASE_ADDR_MASK; sp = to_shadow_page(root); mmu_sync_children(vcpu, sp); } } kvm_mmu_audit(vcpu, AUDIT_POST_SYNC); write_unlock(&vcpu->kvm->mmu_lock); } static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gpa_t vaddr, u32 access, struct x86_exception *exception) { if (exception) exception->error_code = 0; return vaddr; } static gpa_t nonpaging_gva_to_gpa_nested(struct kvm_vcpu *vcpu, gpa_t vaddr, u32 access, struct x86_exception *exception) { if (exception) exception->error_code = 0; return vcpu->arch.nested_mmu.translate_gpa(vcpu, vaddr, access, exception); } static bool __is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check, u64 pte, int level) { int bit7 = (pte >> 7) & 1; return pte & rsvd_check->rsvd_bits_mask[bit7][level-1]; } static bool __is_bad_mt_xwr(struct rsvd_bits_validate *rsvd_check, u64 pte) { return rsvd_check->bad_mt_xwr & BIT_ULL(pte & 0x3f); } static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) { /* * A nested guest cannot use the MMIO cache if it is using nested * page tables, because cr2 is a nGPA while the cache stores GPAs. */ if (mmu_is_nested(vcpu)) return false; if (direct) return vcpu_match_mmio_gpa(vcpu, addr); return vcpu_match_mmio_gva(vcpu, addr); } /* * Return the level of the lowest level SPTE added to sptes. * That SPTE may be non-present. */ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) { struct kvm_shadow_walk_iterator iterator; int leaf = -1; u64 spte; walk_shadow_page_lockless_begin(vcpu); for (shadow_walk_init(&iterator, vcpu, addr), *root_level = iterator.level; shadow_walk_okay(&iterator); __shadow_walk_next(&iterator, spte)) { leaf = iterator.level; spte = mmu_spte_get_lockless(iterator.sptep); sptes[leaf] = spte; if (!is_shadow_present_pte(spte)) break; } walk_shadow_page_lockless_end(vcpu); return leaf; } /* return true if reserved bit(s) are detected on a valid, non-MMIO SPTE. */ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) { u64 sptes[PT64_ROOT_MAX_LEVEL + 1]; struct rsvd_bits_validate *rsvd_check; int root, leaf, level; bool reserved = false; if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) { *sptep = 0ull; return reserved; } if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root); else leaf = get_walk(vcpu, addr, sptes, &root); if (unlikely(leaf < 0)) { *sptep = 0ull; return reserved; } *sptep = sptes[leaf]; /* * Skip reserved bits checks on the terminal leaf if it's not a valid * SPTE. Note, this also (intentionally) skips MMIO SPTEs, which, by * design, always have reserved bits set. The purpose of the checks is * to detect reserved bits on non-MMIO SPTEs. i.e. buggy SPTEs. */ if (!is_shadow_present_pte(sptes[leaf])) leaf++; rsvd_check = &vcpu->arch.mmu->shadow_zero_check; for (level = root; level >= leaf; level--) /* * Use a bitwise-OR instead of a logical-OR to aggregate the * reserved bit and EPT's invalid memtype/XWR checks to avoid * adding a Jcc in the loop. */ reserved |= __is_bad_mt_xwr(rsvd_check, sptes[level]) | __is_rsvd_bits_set(rsvd_check, sptes[level], level); if (reserved) { pr_err("%s: reserved bits set on MMU-present spte, addr 0x%llx, hierarchy:\n", __func__, addr); for (level = root; level >= leaf; level--) pr_err("------ spte = 0x%llx level = %d, rsvd bits = 0x%llx", sptes[level], level, rsvd_check->rsvd_bits_mask[(sptes[level] >> 7) & 1][level-1]); } return reserved; } static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct) { u64 spte; bool reserved; if (mmio_info_in_cache(vcpu, addr, direct)) return RET_PF_EMULATE; reserved = get_mmio_spte(vcpu, addr, &spte); if (WARN_ON(reserved)) return -EINVAL; if (is_mmio_spte(spte)) { gfn_t gfn = get_mmio_spte_gfn(spte); unsigned int access = get_mmio_spte_access(spte); if (!check_mmio_spte(vcpu, spte)) return RET_PF_INVALID; if (direct) addr = 0; trace_handle_mmio_page_fault(addr, gfn, access); vcpu_cache_mmio_info(vcpu, addr, gfn, access); return RET_PF_EMULATE; } /* * If the page table is zapped by other cpus, let CPU fault again on * the address. */ return RET_PF_RETRY; } static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu, u32 error_code, gfn_t gfn) { if (unlikely(error_code & PFERR_RSVD_MASK)) return false; if (!(error_code & PFERR_PRESENT_MASK) || !(error_code & PFERR_WRITE_MASK)) return false; /* * guest is writing the page which is write tracked which can * not be fixed by page fault handler. */ if (kvm_page_track_is_active(vcpu, gfn, KVM_PAGE_TRACK_WRITE)) return true; return false; } static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) { struct kvm_shadow_walk_iterator iterator; u64 spte; walk_shadow_page_lockless_begin(vcpu); for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) { clear_sp_write_flooding_count(iterator.sptep); if (!is_shadow_present_pte(spte)) break; } walk_shadow_page_lockless_end(vcpu); } static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, gfn_t gfn) { struct kvm_arch_async_pf arch; arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; arch.gfn = gfn; arch.direct_map = vcpu->arch.mmu->direct_map; arch.cr3 = vcpu->arch.mmu->get_guest_pgd(vcpu); return kvm_setup_async_pf(vcpu, cr2_or_gpa, kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); } static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, gpa_t cr2_or_gpa, kvm_pfn_t *pfn, hva_t *hva, bool write, bool *writable) { struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); bool async; /* * Retry the page fault if the gfn hit a memslot that is being deleted * or moved. This ensures any existing SPTEs for the old memslot will * be zapped before KVM inserts a new MMIO SPTE for the gfn. */ if (slot && (slot->flags & KVM_MEMSLOT_INVALID)) return true; /* Don't expose private memslots to L2. */ if (is_guest_mode(vcpu) && !kvm_is_visible_memslot(slot)) { *pfn = KVM_PFN_NOSLOT; *writable = false; return false; } async = false; *pfn = __gfn_to_pfn_memslot(slot, gfn, false, &async, write, writable, hva); if (!async) return false; /* *pfn has correct page already */ if (!prefault && kvm_can_do_async_pf(vcpu)) { trace_kvm_try_async_get_page(cr2_or_gpa, gfn); if (kvm_find_async_pf_gfn(vcpu, gfn)) { trace_kvm_async_pf_doublefault(cr2_or_gpa, gfn); kvm_make_request(KVM_REQ_APF_HALT, vcpu); return true; } else if (kvm_arch_setup_async_pf(vcpu, cr2_or_gpa, gfn)) return true; } *pfn = __gfn_to_pfn_memslot(slot, gfn, false, NULL, write, writable, hva); return false; } static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, bool prefault, int max_level, bool is_tdp) { bool write = error_code & PFERR_WRITE_MASK; bool map_writable; gfn_t gfn = gpa >> PAGE_SHIFT; unsigned long mmu_seq; kvm_pfn_t pfn; hva_t hva; int r; if (page_fault_handle_page_track(vcpu, error_code, gfn)) return RET_PF_EMULATE; if (!is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) { r = fast_page_fault(vcpu, gpa, error_code); if (r != RET_PF_INVALID) return r; } r = mmu_topup_memory_caches(vcpu, false); if (r) return r; mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, &hva, write, &map_writable)) return RET_PF_RETRY; if (handle_abnormal_pfn(vcpu, is_tdp ? 0 : gpa, gfn, pfn, ACC_ALL, &r)) return r; r = RET_PF_RETRY; if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) read_lock(&vcpu->kvm->mmu_lock); else write_lock(&vcpu->kvm->mmu_lock); if (!is_noslot_pfn(pfn) && mmu_notifier_retry_hva(vcpu->kvm, mmu_seq, hva)) goto out_unlock; r = make_mmu_pages_available(vcpu); if (r) goto out_unlock; if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) r = kvm_tdp_mmu_map(vcpu, gpa, error_code, map_writable, max_level, pfn, prefault); else r = __direct_map(vcpu, gpa, error_code, map_writable, max_level, pfn, prefault, is_tdp); out_unlock: if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa)) read_unlock(&vcpu->kvm->mmu_lock); else write_unlock(&vcpu->kvm->mmu_lock); kvm_release_pfn_clean(pfn); return r; } static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, bool prefault) { pgprintk("%s: gva %lx error %x\n", __func__, gpa, error_code); /* This path builds a PAE pagetable, we can map 2mb pages at maximum. */ return direct_page_fault(vcpu, gpa & PAGE_MASK, error_code, prefault, PG_LEVEL_2M, false); } int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, u64 fault_address, char *insn, int insn_len) { int r = 1; u32 flags = vcpu->arch.apf.host_apf_flags; #ifndef CONFIG_X86_64 /* A 64-bit CR2 should be impossible on 32-bit KVM. */ if (WARN_ON_ONCE(fault_address >> 32)) return -EFAULT; #endif vcpu->arch.l1tf_flush_l1d = true; if (!flags) { trace_kvm_page_fault(fault_address, error_code); if (kvm_event_needs_reinjection(vcpu)) kvm_mmu_unprotect_page_virt(vcpu, fault_address); r = kvm_mmu_page_fault(vcpu, fault_address, error_code, insn, insn_len); } else if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { vcpu->arch.apf.host_apf_flags = 0; local_irq_disable(); kvm_async_pf_task_wait_schedule(fault_address); local_irq_enable(); } else { WARN_ONCE(1, "Unexpected host async PF flags: %x\n", flags); } return r; } EXPORT_SYMBOL_GPL(kvm_handle_page_fault); int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, bool prefault) { int max_level; for (max_level = KVM_MAX_HUGEPAGE_LEVEL; max_level > PG_LEVEL_4K; max_level--) { int page_num = KVM_PAGES_PER_HPAGE(max_level); gfn_t base = (gpa >> PAGE_SHIFT) & ~(page_num - 1); if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) break; } return direct_page_fault(vcpu, gpa, error_code, prefault, max_level, true); } static void nonpaging_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { context->page_fault = nonpaging_page_fault; context->gva_to_gpa = nonpaging_gva_to_gpa; context->sync_page = nonpaging_sync_page; context->invlpg = NULL; context->root_level = 0; context->shadow_root_level = PT32E_ROOT_LEVEL; context->direct_map = true; context->nx = false; } static inline bool is_root_usable(struct kvm_mmu_root_info *root, gpa_t pgd, union kvm_mmu_page_role role) { return (role.direct || pgd == root->pgd) && VALID_PAGE(root->hpa) && to_shadow_page(root->hpa) && role.word == to_shadow_page(root->hpa)->role.word; } /* * Find out if a previously cached root matching the new pgd/role is available. * The current root is also inserted into the cache. * If a matching root was found, it is assigned to kvm_mmu->root_hpa and true is * returned. * Otherwise, the LRU root from the cache is assigned to kvm_mmu->root_hpa and * false is returned. This root should now be freed by the caller. */ static bool cached_root_available(struct kvm_vcpu *vcpu, gpa_t new_pgd, union kvm_mmu_page_role new_role) { uint i; struct kvm_mmu_root_info root; struct kvm_mmu *mmu = vcpu->arch.mmu; root.pgd = mmu->root_pgd; root.hpa = mmu->root_hpa; if (is_root_usable(&root, new_pgd, new_role)) return true; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { swap(root, mmu->prev_roots[i]); if (is_root_usable(&root, new_pgd, new_role)) break; } mmu->root_hpa = root.hpa; mmu->root_pgd = root.pgd; return i < KVM_MMU_NUM_PREV_ROOTS; } static bool fast_pgd_switch(struct kvm_vcpu *vcpu, gpa_t new_pgd, union kvm_mmu_page_role new_role) { struct kvm_mmu *mmu = vcpu->arch.mmu; /* * For now, limit the fast switch to 64-bit hosts+VMs in order to avoid * having to deal with PDPTEs. We may add support for 32-bit hosts/VMs * later if necessary. */ if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL && mmu->root_level >= PT64_ROOT_4LEVEL) return cached_root_available(vcpu, new_pgd, new_role); return false; } static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, union kvm_mmu_page_role new_role, bool skip_tlb_flush, bool skip_mmu_sync) { if (!fast_pgd_switch(vcpu, new_pgd, new_role)) { kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT); return; } /* * It's possible that the cached previous root page is obsolete because * of a change in the MMU generation number. However, changing the * generation number is accompanied by KVM_REQ_MMU_RELOAD, which will * free the root set here and allocate a new one. */ kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); if (!skip_mmu_sync || force_flush_and_sync_on_reuse) kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); if (!skip_tlb_flush || force_flush_and_sync_on_reuse) kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); /* * The last MMIO access's GVA and GPA are cached in the VCPU. When * switching to a new CR3, that GVA->GPA mapping may no longer be * valid. So clear any cached MMIO info even when we don't need to sync * the shadow page tables. */ vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); /* * If this is a direct root page, it doesn't have a write flooding * count. Otherwise, clear the write flooding count. */ if (!new_role.direct) __clear_sp_write_flooding_count( to_shadow_page(vcpu->arch.mmu->root_hpa)); } void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, bool skip_tlb_flush, bool skip_mmu_sync) { __kvm_mmu_new_pgd(vcpu, new_pgd, kvm_mmu_calc_root_page_role(vcpu), skip_tlb_flush, skip_mmu_sync); } EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd); static unsigned long get_cr3(struct kvm_vcpu *vcpu) { return kvm_read_cr3(vcpu); } static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, unsigned int access, int *nr_present) { if (unlikely(is_mmio_spte(*sptep))) { if (gfn != get_mmio_spte_gfn(*sptep)) { mmu_spte_clear_no_track(sptep); return true; } (*nr_present)++; mark_mmio_spte(vcpu, sptep, gfn, access); return true; } return false; } static inline bool is_last_gpte(struct kvm_mmu *mmu, unsigned level, unsigned gpte) { /* * The RHS has bit 7 set iff level < mmu->last_nonleaf_level. * If it is clear, there are no large pages at this level, so clear * PT_PAGE_SIZE_MASK in gpte if that is the case. */ gpte &= level - mmu->last_nonleaf_level; /* * PG_LEVEL_4K always terminates. The RHS has bit 7 set * iff level <= PG_LEVEL_4K, which for our purpose means * level == PG_LEVEL_4K; set PT_PAGE_SIZE_MASK in gpte then. */ gpte |= level - PG_LEVEL_4K - 1; return gpte & PT_PAGE_SIZE_MASK; } #define PTTYPE_EPT 18 /* arbitrary */ #define PTTYPE PTTYPE_EPT #include "paging_tmpl.h" #undef PTTYPE #define PTTYPE 64 #include "paging_tmpl.h" #undef PTTYPE #define PTTYPE 32 #include "paging_tmpl.h" #undef PTTYPE static void __reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, struct rsvd_bits_validate *rsvd_check, u64 pa_bits_rsvd, int level, bool nx, bool gbpages, bool pse, bool amd) { u64 gbpages_bit_rsvd = 0; u64 nonleaf_bit8_rsvd = 0; u64 high_bits_rsvd; rsvd_check->bad_mt_xwr = 0; if (!gbpages) gbpages_bit_rsvd = rsvd_bits(7, 7); if (level == PT32E_ROOT_LEVEL) high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 62); else high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); /* Note, NX doesn't exist in PDPTEs, this is handled below. */ if (!nx) high_bits_rsvd |= rsvd_bits(63, 63); /* * Non-leaf PML4Es and PDPEs reserve bit 8 (which would be the G bit for * leaf entries) on AMD CPUs only. */ if (amd) nonleaf_bit8_rsvd = rsvd_bits(8, 8); switch (level) { case PT32_ROOT_LEVEL: /* no rsvd bits for 2 level 4K page table entries */ rsvd_check->rsvd_bits_mask[0][1] = 0; rsvd_check->rsvd_bits_mask[0][0] = 0; rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; if (!pse) { rsvd_check->rsvd_bits_mask[1][1] = 0; break; } if (is_cpuid_PSE36()) /* 36bits PSE 4MB page */ rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(17, 21); else /* 32 bits PSE 4MB page */ rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(13, 21); break; case PT32E_ROOT_LEVEL: rsvd_check->rsvd_bits_mask[0][2] = rsvd_bits(63, 63) | high_bits_rsvd | rsvd_bits(5, 8) | rsvd_bits(1, 2); /* PDPTE */ rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; /* PDE */ rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; /* PTE */ rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(13, 20); /* large page */ rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; break; case PT64_ROOT_5LEVEL: rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | nonleaf_bit8_rsvd | rsvd_bits(7, 7); rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4]; fallthrough; case PT64_ROOT_4LEVEL: rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | nonleaf_bit8_rsvd | rsvd_bits(7, 7); rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | gbpages_bit_rsvd; rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3]; rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | gbpages_bit_rsvd | rsvd_bits(13, 29); rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(13, 20); /* large page */ rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; break; } } static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { __reset_rsvds_bits_mask(vcpu, &context->guest_rsvd_check, vcpu->arch.reserved_gpa_bits, context->root_level, context->nx, guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES), is_pse(vcpu), guest_cpuid_is_amd_or_hygon(vcpu)); } static void __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, u64 pa_bits_rsvd, bool execonly) { u64 high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); u64 bad_mt_xwr; rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | rsvd_bits(3, 7); rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | rsvd_bits(3, 7); rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | rsvd_bits(3, 6); rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd | rsvd_bits(3, 6); rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; /* large page */ rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4]; rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3]; rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | rsvd_bits(12, 29); rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(12, 20); rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; bad_mt_xwr = 0xFFull << (2 * 8); /* bits 3..5 must not be 2 */ bad_mt_xwr |= 0xFFull << (3 * 8); /* bits 3..5 must not be 3 */ bad_mt_xwr |= 0xFFull << (7 * 8); /* bits 3..5 must not be 7 */ bad_mt_xwr |= REPEAT_BYTE(1ull << 2); /* bits 0..2 must not be 010 */ bad_mt_xwr |= REPEAT_BYTE(1ull << 6); /* bits 0..2 must not be 110 */ if (!execonly) { /* bits 0..2 must not be 100 unless VMX capabilities allow it */ bad_mt_xwr |= REPEAT_BYTE(1ull << 4); } rsvd_check->bad_mt_xwr = bad_mt_xwr; } static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, struct kvm_mmu *context, bool execonly) { __reset_rsvds_bits_mask_ept(&context->guest_rsvd_check, vcpu->arch.reserved_gpa_bits, execonly); } static inline u64 reserved_hpa_bits(void) { return rsvd_bits(shadow_phys_bits, 63); } /* * the page table on host is the shadow page table for the page * table in guest or amd nested guest, its mmu features completely * follow the features in guest. */ void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { bool uses_nx = context->nx || context->mmu_role.base.smep_andnot_wp; struct rsvd_bits_validate *shadow_zero_check; int i; /* * Passing "true" to the last argument is okay; it adds a check * on bit 8 of the SPTEs which KVM doesn't use anyway. */ shadow_zero_check = &context->shadow_zero_check; __reset_rsvds_bits_mask(vcpu, shadow_zero_check, reserved_hpa_bits(), context->shadow_root_level, uses_nx, guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES), is_pse(vcpu), true); if (!shadow_me_mask) return; for (i = context->shadow_root_level; --i >= 0;) { shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask; shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask; } } EXPORT_SYMBOL_GPL(reset_shadow_zero_bits_mask); static inline bool boot_cpu_is_amd(void) { WARN_ON_ONCE(!tdp_enabled); return shadow_x_mask == 0; } /* * the direct page table on host, use as much mmu features as * possible, however, kvm currently does not do execution-protection. */ static void reset_tdp_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { struct rsvd_bits_validate *shadow_zero_check; int i; shadow_zero_check = &context->shadow_zero_check; if (boot_cpu_is_amd()) __reset_rsvds_bits_mask(vcpu, shadow_zero_check, reserved_hpa_bits(), context->shadow_root_level, false, boot_cpu_has(X86_FEATURE_GBPAGES), true, true); else __reset_rsvds_bits_mask_ept(shadow_zero_check, reserved_hpa_bits(), false); if (!shadow_me_mask) return; for (i = context->shadow_root_level; --i >= 0;) { shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask; shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask; } } /* * as the comments in reset_shadow_zero_bits_mask() except it * is the shadow page table for intel nested guest. */ static void reset_ept_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context, bool execonly) { __reset_rsvds_bits_mask_ept(&context->shadow_zero_check, reserved_hpa_bits(), execonly); } #define BYTE_MASK(access) \ ((1 & (access) ? 2 : 0) | \ (2 & (access) ? 4 : 0) | \ (3 & (access) ? 8 : 0) | \ (4 & (access) ? 16 : 0) | \ (5 & (access) ? 32 : 0) | \ (6 & (access) ? 64 : 0) | \ (7 & (access) ? 128 : 0)) static void update_permission_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, bool ept) { unsigned byte; const u8 x = BYTE_MASK(ACC_EXEC_MASK); const u8 w = BYTE_MASK(ACC_WRITE_MASK); const u8 u = BYTE_MASK(ACC_USER_MASK); bool cr4_smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP) != 0; bool cr4_smap = kvm_read_cr4_bits(vcpu, X86_CR4_SMAP) != 0; bool cr0_wp = is_write_protection(vcpu); for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) { unsigned pfec = byte << 1; /* * Each "*f" variable has a 1 bit for each UWX value * that causes a fault with the given PFEC. */ /* Faults from writes to non-writable pages */ u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0; /* Faults from user mode accesses to supervisor pages */ u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0; /* Faults from fetches of non-executable pages*/ u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0; /* Faults from kernel mode fetches of user pages */ u8 smepf = 0; /* Faults from kernel mode accesses of user pages */ u8 smapf = 0; if (!ept) { /* Faults from kernel mode accesses to user pages */ u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u; /* Not really needed: !nx will cause pte.nx to fault */ if (!mmu->nx) ff = 0; /* Allow supervisor writes if !cr0.wp */ if (!cr0_wp) wf = (pfec & PFERR_USER_MASK) ? wf : 0; /* Disallow supervisor fetches of user code if cr4.smep */ if (cr4_smep) smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0; /* * SMAP:kernel-mode data accesses from user-mode * mappings should fault. A fault is considered * as a SMAP violation if all of the following * conditions are true: * - X86_CR4_SMAP is set in CR4 * - A user page is accessed * - The access is not a fetch * - Page fault in kernel mode * - if CPL = 3 or X86_EFLAGS_AC is clear * * Here, we cover the first three conditions. * The fourth is computed dynamically in permission_fault(); * PFERR_RSVD_MASK bit will be set in PFEC if the access is * *not* subject to SMAP restrictions. */ if (cr4_smap) smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf; } mmu->permissions[byte] = ff | uf | wf | smepf | smapf; } } /* * PKU is an additional mechanism by which the paging controls access to * user-mode addresses based on the value in the PKRU register. Protection * key violations are reported through a bit in the page fault error code. * Unlike other bits of the error code, the PK bit is not known at the * call site of e.g. gva_to_gpa; it must be computed directly in * permission_fault based on two bits of PKRU, on some machine state (CR4, * CR0, EFER, CPL), and on other bits of the error code and the page tables. * * In particular the following conditions come from the error code, the * page tables and the machine state: * - PK is always zero unless CR4.PKE=1 and EFER.LMA=1 * - PK is always zero if RSVD=1 (reserved bit set) or F=1 (instruction fetch) * - PK is always zero if U=0 in the page tables * - PKRU.WD is ignored if CR0.WP=0 and the access is a supervisor access. * * The PKRU bitmask caches the result of these four conditions. The error * code (minus the P bit) and the page table's U bit form an index into the * PKRU bitmask. Two bits of the PKRU bitmask are then extracted and ANDed * with the two bits of the PKRU register corresponding to the protection key. * For the first three conditions above the bits will be 00, thus masking * away both AD and WD. For all reads or if the last condition holds, WD * only will be masked away. */ static void update_pkru_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, bool ept) { unsigned bit; bool wp; if (ept) { mmu->pkru_mask = 0; return; } /* PKEY is enabled only if CR4.PKE and EFER.LMA are both set. */ if (!kvm_read_cr4_bits(vcpu, X86_CR4_PKE) || !is_long_mode(vcpu)) { mmu->pkru_mask = 0; return; } wp = is_write_protection(vcpu); for (bit = 0; bit < ARRAY_SIZE(mmu->permissions); ++bit) { unsigned pfec, pkey_bits; bool check_pkey, check_write, ff, uf, wf, pte_user; pfec = bit << 1; ff = pfec & PFERR_FETCH_MASK; uf = pfec & PFERR_USER_MASK; wf = pfec & PFERR_WRITE_MASK; /* PFEC.RSVD is replaced by ACC_USER_MASK. */ pte_user = pfec & PFERR_RSVD_MASK; /* * Only need to check the access which is not an * instruction fetch and is to a user page. */ check_pkey = (!ff && pte_user); /* * write access is controlled by PKRU if it is a * user access or CR0.WP = 1. */ check_write = check_pkey && wf && (uf || wp); /* PKRU.AD stops both read and write access. */ pkey_bits = !!check_pkey; /* PKRU.WD stops write access. */ pkey_bits |= (!!check_write) << 1; mmu->pkru_mask |= (pkey_bits & 3) << pfec; } } static void update_last_nonleaf_level(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) { unsigned root_level = mmu->root_level; mmu->last_nonleaf_level = root_level; if (root_level == PT32_ROOT_LEVEL && is_pse(vcpu)) mmu->last_nonleaf_level++; } static void paging64_init_context_common(struct kvm_vcpu *vcpu, struct kvm_mmu *context, int level) { context->nx = is_nx(vcpu); context->root_level = level; reset_rsvds_bits_mask(vcpu, context); update_permission_bitmask(vcpu, context, false); update_pkru_bitmask(vcpu, context, false); update_last_nonleaf_level(vcpu, context); MMU_WARN_ON(!is_pae(vcpu)); context->page_fault = paging64_page_fault; context->gva_to_gpa = paging64_gva_to_gpa; context->sync_page = paging64_sync_page; context->invlpg = paging64_invlpg; context->shadow_root_level = level; context->direct_map = false; } static void paging64_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { int root_level = is_la57_mode(vcpu) ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL; paging64_init_context_common(vcpu, context, root_level); } static void paging32_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { context->nx = false; context->root_level = PT32_ROOT_LEVEL; reset_rsvds_bits_mask(vcpu, context); update_permission_bitmask(vcpu, context, false); update_pkru_bitmask(vcpu, context, false); update_last_nonleaf_level(vcpu, context); context->page_fault = paging32_page_fault; context->gva_to_gpa = paging32_gva_to_gpa; context->sync_page = paging32_sync_page; context->invlpg = paging32_invlpg; context->shadow_root_level = PT32E_ROOT_LEVEL; context->direct_map = false; } static void paging32E_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { paging64_init_context_common(vcpu, context, PT32E_ROOT_LEVEL); } static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu) { union kvm_mmu_extended_role ext = {0}; ext.cr0_pg = !!is_paging(vcpu); ext.cr4_pae = !!is_pae(vcpu); ext.cr4_smep = !!kvm_read_cr4_bits(vcpu, X86_CR4_SMEP); ext.cr4_smap = !!kvm_read_cr4_bits(vcpu, X86_CR4_SMAP); ext.cr4_pse = !!is_pse(vcpu); ext.cr4_pke = !!kvm_read_cr4_bits(vcpu, X86_CR4_PKE); ext.maxphyaddr = cpuid_maxphyaddr(vcpu); ext.valid = 1; return ext; } static union kvm_mmu_role kvm_calc_mmu_role_common(struct kvm_vcpu *vcpu, bool base_only) { union kvm_mmu_role role = {0}; role.base.access = ACC_ALL; role.base.nxe = !!is_nx(vcpu); role.base.cr0_wp = is_write_protection(vcpu); role.base.smm = is_smm(vcpu); role.base.guest_mode = is_guest_mode(vcpu); if (base_only) return role; role.ext = kvm_calc_mmu_role_ext(vcpu); return role; } static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu) { /* Use 5-level TDP if and only if it's useful/necessary. */ if (max_tdp_level == 5 && cpuid_maxphyaddr(vcpu) <= 48) return 4; return max_tdp_level; } static union kvm_mmu_role kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu, bool base_only) { union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, base_only); role.base.ad_disabled = (shadow_accessed_mask == 0); role.base.level = kvm_mmu_get_tdp_level(vcpu); role.base.direct = true; role.base.gpte_is_8_bytes = true; return role; } static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = &vcpu->arch.root_mmu; union kvm_mmu_role new_role = kvm_calc_tdp_mmu_root_page_role(vcpu, false); if (new_role.as_u64 == context->mmu_role.as_u64) return; context->mmu_role.as_u64 = new_role.as_u64; context->page_fault = kvm_tdp_page_fault; context->sync_page = nonpaging_sync_page; context->invlpg = NULL; context->shadow_root_level = kvm_mmu_get_tdp_level(vcpu); context->direct_map = true; context->get_guest_pgd = get_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; if (!is_paging(vcpu)) { context->nx = false; context->gva_to_gpa = nonpaging_gva_to_gpa; context->root_level = 0; } else if (is_long_mode(vcpu)) { context->nx = is_nx(vcpu); context->root_level = is_la57_mode(vcpu) ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL; reset_rsvds_bits_mask(vcpu, context); context->gva_to_gpa = paging64_gva_to_gpa; } else if (is_pae(vcpu)) { context->nx = is_nx(vcpu); context->root_level = PT32E_ROOT_LEVEL; reset_rsvds_bits_mask(vcpu, context); context->gva_to_gpa = paging64_gva_to_gpa; } else { context->nx = false; context->root_level = PT32_ROOT_LEVEL; reset_rsvds_bits_mask(vcpu, context); context->gva_to_gpa = paging32_gva_to_gpa; } update_permission_bitmask(vcpu, context, false); update_pkru_bitmask(vcpu, context, false); update_last_nonleaf_level(vcpu, context); reset_tdp_shadow_zero_bits_mask(vcpu, context); } static union kvm_mmu_role kvm_calc_shadow_root_page_role_common(struct kvm_vcpu *vcpu, bool base_only) { union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, base_only); role.base.smep_andnot_wp = role.ext.cr4_smep && !is_write_protection(vcpu); role.base.smap_andnot_wp = role.ext.cr4_smap && !is_write_protection(vcpu); role.base.gpte_is_8_bytes = !!is_pae(vcpu); return role; } static union kvm_mmu_role kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu, bool base_only) { union kvm_mmu_role role = kvm_calc_shadow_root_page_role_common(vcpu, base_only); role.base.direct = !is_paging(vcpu); if (!is_long_mode(vcpu)) role.base.level = PT32E_ROOT_LEVEL; else if (is_la57_mode(vcpu)) role.base.level = PT64_ROOT_5LEVEL; else role.base.level = PT64_ROOT_4LEVEL; return role; } static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context, u32 cr0, u32 cr4, u32 efer, union kvm_mmu_role new_role) { if (!(cr0 & X86_CR0_PG)) nonpaging_init_context(vcpu, context); else if (efer & EFER_LMA) paging64_init_context(vcpu, context); else if (cr4 & X86_CR4_PAE) paging32E_init_context(vcpu, context); else paging32_init_context(vcpu, context); context->mmu_role.as_u64 = new_role.as_u64; reset_shadow_zero_bits_mask(vcpu, context); } static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer) { struct kvm_mmu *context = &vcpu->arch.root_mmu; union kvm_mmu_role new_role = kvm_calc_shadow_mmu_root_page_role(vcpu, false); if (new_role.as_u64 != context->mmu_role.as_u64) shadow_mmu_init_context(vcpu, context, cr0, cr4, efer, new_role); } static union kvm_mmu_role kvm_calc_shadow_npt_root_page_role(struct kvm_vcpu *vcpu) { union kvm_mmu_role role = kvm_calc_shadow_root_page_role_common(vcpu, false); role.base.direct = false; role.base.level = kvm_mmu_get_tdp_level(vcpu); return role; } void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer, gpa_t nested_cr3) { struct kvm_mmu *context = &vcpu->arch.guest_mmu; union kvm_mmu_role new_role = kvm_calc_shadow_npt_root_page_role(vcpu); __kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base, false, false); if (new_role.as_u64 != context->mmu_role.as_u64) { shadow_mmu_init_context(vcpu, context, cr0, cr4, efer, new_role); /* * Override the level set by the common init helper, nested TDP * always uses the host's TDP configuration. */ context->shadow_root_level = new_role.base.level; } } EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu); static union kvm_mmu_role kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty, bool execonly, u8 level) { union kvm_mmu_role role = {0}; /* SMM flag is inherited from root_mmu */ role.base.smm = vcpu->arch.root_mmu.mmu_role.base.smm; role.base.level = level; role.base.gpte_is_8_bytes = true; role.base.direct = false; role.base.ad_disabled = !accessed_dirty; role.base.guest_mode = true; role.base.access = ACC_ALL; /* * WP=1 and NOT_WP=1 is an impossible combination, use WP and the * SMAP variation to denote shadow EPT entries. */ role.base.cr0_wp = true; role.base.smap_andnot_wp = true; role.ext = kvm_calc_mmu_role_ext(vcpu); role.ext.execonly = execonly; return role; } void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, bool accessed_dirty, gpa_t new_eptp) { struct kvm_mmu *context = &vcpu->arch.guest_mmu; u8 level = vmx_eptp_page_walk_level(new_eptp); union kvm_mmu_role new_role = kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, execonly, level); __kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base, true, true); if (new_role.as_u64 == context->mmu_role.as_u64) return; context->shadow_root_level = level; context->nx = true; context->ept_ad = accessed_dirty; context->page_fault = ept_page_fault; context->gva_to_gpa = ept_gva_to_gpa; context->sync_page = ept_sync_page; context->invlpg = ept_invlpg; context->root_level = level; context->direct_map = false; context->mmu_role.as_u64 = new_role.as_u64; update_permission_bitmask(vcpu, context, true); update_pkru_bitmask(vcpu, context, true); update_last_nonleaf_level(vcpu, context); reset_rsvds_bits_mask_ept(vcpu, context, execonly); reset_ept_shadow_zero_bits_mask(vcpu, context, execonly); } EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu); static void init_kvm_softmmu(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = &vcpu->arch.root_mmu; kvm_init_shadow_mmu(vcpu, kvm_read_cr0_bits(vcpu, X86_CR0_PG), kvm_read_cr4_bits(vcpu, X86_CR4_PAE), vcpu->arch.efer); context->get_guest_pgd = get_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; } static union kvm_mmu_role kvm_calc_nested_mmu_role(struct kvm_vcpu *vcpu) { union kvm_mmu_role role = kvm_calc_shadow_root_page_role_common(vcpu, false); /* * Nested MMUs are used only for walking L2's gva->gpa, they never have * shadow pages of their own and so "direct" has no meaning. Set it * to "true" to try to detect bogus usage of the nested MMU. */ role.base.direct = true; if (!is_paging(vcpu)) role.base.level = 0; else if (is_long_mode(vcpu)) role.base.level = is_la57_mode(vcpu) ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL; else if (is_pae(vcpu)) role.base.level = PT32E_ROOT_LEVEL; else role.base.level = PT32_ROOT_LEVEL; return role; } static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu) { union kvm_mmu_role new_role = kvm_calc_nested_mmu_role(vcpu); struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; if (new_role.as_u64 == g_context->mmu_role.as_u64) return; g_context->mmu_role.as_u64 = new_role.as_u64; g_context->get_guest_pgd = get_cr3; g_context->get_pdptr = kvm_pdptr_read; g_context->inject_page_fault = kvm_inject_page_fault; /* * L2 page tables are never shadowed, so there is no need to sync * SPTEs. */ g_context->invlpg = NULL; /* * Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using * L1's nested page tables (e.g. EPT12). The nested translation * of l2_gva to l1_gpa is done by arch.nested_mmu.gva_to_gpa using * L2's page tables as the first level of translation and L1's * nested page tables as the second level of translation. Basically * the gva_to_gpa functions between mmu and nested_mmu are swapped. */ if (!is_paging(vcpu)) { g_context->nx = false; g_context->root_level = 0; g_context->gva_to_gpa = nonpaging_gva_to_gpa_nested; } else if (is_long_mode(vcpu)) { g_context->nx = is_nx(vcpu); g_context->root_level = is_la57_mode(vcpu) ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL; reset_rsvds_bits_mask(vcpu, g_context); g_context->gva_to_gpa = paging64_gva_to_gpa_nested; } else if (is_pae(vcpu)) { g_context->nx = is_nx(vcpu); g_context->root_level = PT32E_ROOT_LEVEL; reset_rsvds_bits_mask(vcpu, g_context); g_context->gva_to_gpa = paging64_gva_to_gpa_nested; } else { g_context->nx = false; g_context->root_level = PT32_ROOT_LEVEL; reset_rsvds_bits_mask(vcpu, g_context); g_context->gva_to_gpa = paging32_gva_to_gpa_nested; } update_permission_bitmask(vcpu, g_context, false); update_pkru_bitmask(vcpu, g_context, false); update_last_nonleaf_level(vcpu, g_context); } void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots) { if (reset_roots) { uint i; vcpu->arch.mmu->root_hpa = INVALID_PAGE; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) vcpu->arch.mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; } if (mmu_is_nested(vcpu)) init_kvm_nested_mmu(vcpu); else if (tdp_enabled) init_kvm_tdp_mmu(vcpu); else init_kvm_softmmu(vcpu); } EXPORT_SYMBOL_GPL(kvm_init_mmu); static union kvm_mmu_page_role kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu) { union kvm_mmu_role role; if (tdp_enabled) role = kvm_calc_tdp_mmu_root_page_role(vcpu, true); else role = kvm_calc_shadow_mmu_root_page_role(vcpu, true); return role.base; } void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) { kvm_mmu_unload(vcpu); kvm_init_mmu(vcpu, true); } EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); int kvm_mmu_load(struct kvm_vcpu *vcpu) { int r; r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->direct_map); if (r) goto out; r = mmu_alloc_special_roots(vcpu); if (r) goto out; if (vcpu->arch.mmu->direct_map) r = mmu_alloc_direct_roots(vcpu); else r = mmu_alloc_shadow_roots(vcpu); if (r) goto out; kvm_mmu_sync_roots(vcpu); kvm_mmu_load_pgd(vcpu); static_call(kvm_x86_tlb_flush_current)(vcpu); out: return r; } void kvm_mmu_unload(struct kvm_vcpu *vcpu) { kvm_mmu_free_roots(vcpu, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); WARN_ON(VALID_PAGE(vcpu->arch.root_mmu.root_hpa)); kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); WARN_ON(VALID_PAGE(vcpu->arch.guest_mmu.root_hpa)); } static bool need_remote_flush(u64 old, u64 new) { if (!is_shadow_present_pte(old)) return false; if (!is_shadow_present_pte(new)) return true; if ((old ^ new) & PT64_BASE_ADDR_MASK) return true; old ^= shadow_nx_mask; new ^= shadow_nx_mask; return (old & ~new & PT64_PERM_MASK) != 0; } static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, int *bytes) { u64 gentry = 0; int r; /* * Assume that the pte write on a page table of the same type * as the current vcpu paging mode since we update the sptes only * when they have the same mode. */ if (is_pae(vcpu) && *bytes == 4) { /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ *gpa &= ~(gpa_t)7; *bytes = 8; } if (*bytes == 4 || *bytes == 8) { r = kvm_vcpu_read_guest_atomic(vcpu, *gpa, &gentry, *bytes); if (r) gentry = 0; } return gentry; } /* * If we're seeing too many writes to a page, it may no longer be a page table, * or we may be forking, in which case it is better to unmap the page. */ static bool detect_write_flooding(struct kvm_mmu_page *sp) { /* * Skip write-flooding detected for the sp whose level is 1, because * it can become unsync, then the guest page is not write-protected. */ if (sp->role.level == PG_LEVEL_4K) return false; atomic_inc(&sp->write_flooding_count); return atomic_read(&sp->write_flooding_count) >= 3; } /* * Misaligned accesses are too much trouble to fix up; also, they usually * indicate a page is not used as a page table. */ static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, int bytes) { unsigned offset, pte_size, misaligned; pgprintk("misaligned: gpa %llx bytes %d role %x\n", gpa, bytes, sp->role.word); offset = offset_in_page(gpa); pte_size = sp->role.gpte_is_8_bytes ? 8 : 4; /* * Sometimes, the OS only writes the last one bytes to update status * bits, for example, in linux, andb instruction is used in clear_bit(). */ if (!(offset & (pte_size - 1)) && bytes == 1) return false; misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); misaligned |= bytes < 4; return misaligned; } static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) { unsigned page_offset, quadrant; u64 *spte; int level; page_offset = offset_in_page(gpa); level = sp->role.level; *nspte = 1; if (!sp->role.gpte_is_8_bytes) { page_offset <<= 1; /* 32->64 */ /* * A 32-bit pde maps 4MB while the shadow pdes map * only 2MB. So we need to double the offset again * and zap two pdes instead of one. */ if (level == PT32_ROOT_LEVEL) { page_offset &= ~7; /* kill rounding error */ page_offset <<= 1; *nspte = 2; } quadrant = page_offset >> PAGE_SHIFT; page_offset &= ~PAGE_MASK; if (quadrant != sp->role.quadrant) return NULL; } spte = &sp->spt[page_offset / sizeof(*spte)]; return spte; } static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, int bytes, struct kvm_page_track_notifier_node *node) { gfn_t gfn = gpa >> PAGE_SHIFT; struct kvm_mmu_page *sp; LIST_HEAD(invalid_list); u64 entry, gentry, *spte; int npte; bool remote_flush, local_flush; /* * If we don't have indirect shadow pages, it means no page is * write-protected, so we can exit simply. */ if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) return; remote_flush = local_flush = false; pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); /* * No need to care whether allocation memory is successful * or not since pte prefetch is skipped if it does not have * enough objects in the cache. */ mmu_topup_memory_caches(vcpu, true); write_lock(&vcpu->kvm->mmu_lock); gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes); ++vcpu->kvm->stat.mmu_pte_write; kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE); for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) { if (detect_write_misaligned(sp, gpa, bytes) || detect_write_flooding(sp)) { kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list); ++vcpu->kvm->stat.mmu_flooded; continue; } spte = get_written_sptes(sp, gpa, &npte); if (!spte) continue; local_flush = true; while (npte--) { entry = *spte; mmu_page_zap_pte(vcpu->kvm, sp, spte, NULL); if (gentry && sp->role.level != PG_LEVEL_4K) ++vcpu->kvm->stat.mmu_pde_zapped; if (need_remote_flush(entry, *spte)) remote_flush = true; ++spte; } } kvm_mmu_flush_or_zap(vcpu, &invalid_list, remote_flush, local_flush); kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE); write_unlock(&vcpu->kvm->mmu_lock); } int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, void *insn, int insn_len) { int r, emulation_type = EMULTYPE_PF; bool direct = vcpu->arch.mmu->direct_map; if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa))) return RET_PF_RETRY; r = RET_PF_INVALID; if (unlikely(error_code & PFERR_RSVD_MASK)) { r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct); if (r == RET_PF_EMULATE) goto emulate; } if (r == RET_PF_INVALID) { r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, lower_32_bits(error_code), false); if (WARN_ON_ONCE(r == RET_PF_INVALID)) return -EIO; } if (r < 0) return r; if (r != RET_PF_EMULATE) return 1; /* * Before emulating the instruction, check if the error code * was due to a RO violation while translating the guest page. * This can occur when using nested virtualization with nested * paging in both guests. If true, we simply unprotect the page * and resume the guest. */ if (vcpu->arch.mmu->direct_map && (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE) { kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(cr2_or_gpa)); return 1; } /* * vcpu->arch.mmu.page_fault returned RET_PF_EMULATE, but we can still * optimistically try to just unprotect the page and let the processor * re-execute the instruction that caused the page fault. Do not allow * retrying MMIO emulation, as it's not only pointless but could also * cause us to enter an infinite loop because the processor will keep * faulting on the non-existent MMIO address. Retrying an instruction * from a nested guest is also pointless and dangerous as we are only * explicitly shadowing L1's page tables, i.e. unprotecting something * for L1 isn't going to magically fix whatever issue cause L2 to fail. */ if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu)) emulation_type |= EMULTYPE_ALLOW_RETRY_PF; emulate: return x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, insn_len); } EXPORT_SYMBOL_GPL(kvm_mmu_page_fault); void kvm_mmu_invalidate_gva(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, gva_t gva, hpa_t root_hpa) { int i; /* It's actually a GPA for vcpu->arch.guest_mmu. */ if (mmu != &vcpu->arch.guest_mmu) { /* INVLPG on a non-canonical address is a NOP according to the SDM. */ if (is_noncanonical_address(gva, vcpu)) return; static_call(kvm_x86_tlb_flush_gva)(vcpu, gva); } if (!mmu->invlpg) return; if (root_hpa == INVALID_PAGE) { mmu->invlpg(vcpu, gva, mmu->root_hpa); /* * INVLPG is required to invalidate any global mappings for the VA, * irrespective of PCID. Since it would take us roughly similar amount * of work to determine whether any of the prev_root mappings of the VA * is marked global, or to just sync it blindly, so we might as well * just always sync it. * * Mappings not reachable via the current cr3 or the prev_roots will be * synced when switching to that cr3, so nothing needs to be done here * for them. */ for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) if (VALID_PAGE(mmu->prev_roots[i].hpa)) mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); } else { mmu->invlpg(vcpu, gva, root_hpa); } } void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva) { kvm_mmu_invalidate_gva(vcpu, vcpu->arch.mmu, gva, INVALID_PAGE); ++vcpu->stat.invlpg; } EXPORT_SYMBOL_GPL(kvm_mmu_invlpg); void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid) { struct kvm_mmu *mmu = vcpu->arch.mmu; bool tlb_flush = false; uint i; if (pcid == kvm_get_active_pcid(vcpu)) { mmu->invlpg(vcpu, gva, mmu->root_hpa); tlb_flush = true; } for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { if (VALID_PAGE(mmu->prev_roots[i].hpa) && pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) { mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); tlb_flush = true; } } if (tlb_flush) static_call(kvm_x86_tlb_flush_gva)(vcpu, gva); ++vcpu->stat.invlpg; /* * Mappings not reachable via the current cr3 or the prev_roots will be * synced when switching to that cr3, so nothing needs to be done here * for them. */ } void kvm_configure_mmu(bool enable_tdp, int tdp_max_root_level, int tdp_huge_page_level) { tdp_enabled = enable_tdp; max_tdp_level = tdp_max_root_level; /* * max_huge_page_level reflects KVM's MMU capabilities irrespective * of kernel support, e.g. KVM may be capable of using 1GB pages when * the kernel is not. But, KVM never creates a page size greater than * what is used by the kernel for any given HVA, i.e. the kernel's * capabilities are ultimately consulted by kvm_mmu_hugepage_adjust(). */ if (tdp_enabled) max_huge_page_level = tdp_huge_page_level; else if (boot_cpu_has(X86_FEATURE_GBPAGES)) max_huge_page_level = PG_LEVEL_1G; else max_huge_page_level = PG_LEVEL_2M; } EXPORT_SYMBOL_GPL(kvm_configure_mmu); /* The return value indicates if tlb flush on all vcpus is needed. */ typedef bool (*slot_level_handler) (struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot); /* The caller should hold mmu-lock before calling this function. */ static __always_inline bool slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot, slot_level_handler fn, int start_level, int end_level, gfn_t start_gfn, gfn_t end_gfn, bool flush_on_yield, bool flush) { struct slot_rmap_walk_iterator iterator; for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn, end_gfn, &iterator) { if (iterator.rmap) flush |= fn(kvm, iterator.rmap, memslot); if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { if (flush && flush_on_yield) { kvm_flush_remote_tlbs_with_address(kvm, start_gfn, iterator.gfn - start_gfn + 1); flush = false; } cond_resched_rwlock_write(&kvm->mmu_lock); } } return flush; } static __always_inline bool slot_handle_level(struct kvm *kvm, struct kvm_memory_slot *memslot, slot_level_handler fn, int start_level, int end_level, bool flush_on_yield) { return slot_handle_level_range(kvm, memslot, fn, start_level, end_level, memslot->base_gfn, memslot->base_gfn + memslot->npages - 1, flush_on_yield, false); } static __always_inline bool slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot, slot_level_handler fn, bool flush_on_yield) { return slot_handle_level(kvm, memslot, fn, PG_LEVEL_4K, PG_LEVEL_4K, flush_on_yield); } static void free_mmu_pages(struct kvm_mmu *mmu) { if (!tdp_enabled && mmu->pae_root) set_memory_encrypted((unsigned long)mmu->pae_root, 1); free_page((unsigned long)mmu->pae_root); free_page((unsigned long)mmu->pml4_root); } static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) { struct page *page; int i; mmu->root_hpa = INVALID_PAGE; mmu->root_pgd = 0; mmu->translate_gpa = translate_gpa; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; /* * When using PAE paging, the four PDPTEs are treated as 'root' pages, * while the PDP table is a per-vCPU construct that's allocated at MMU * creation. When emulating 32-bit mode, cr3 is only 32 bits even on * x86_64. Therefore we need to allocate the PDP table in the first * 4GB of memory, which happens to fit the DMA32 zone. TDP paging * generally doesn't use PAE paging and can skip allocating the PDP * table. The main exception, handled here, is SVM's 32-bit NPT. The * other exception is for shadowing L1's 32-bit or PAE NPT on 64-bit * KVM; that horror is handled on-demand by mmu_alloc_shadow_roots(). */ if (tdp_enabled && kvm_mmu_get_tdp_level(vcpu) > PT32E_ROOT_LEVEL) return 0; page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_DMA32); if (!page) return -ENOMEM; mmu->pae_root = page_address(page); /* * CR3 is only 32 bits when PAE paging is used, thus it's impossible to * get the CPU to treat the PDPTEs as encrypted. Decrypt the page so * that KVM's writes and the CPU's reads get along. Note, this is * only necessary when using shadow paging, as 64-bit NPT can get at * the C-bit even when shadowing 32-bit NPT, and SME isn't supported * by 32-bit kernels (when KVM itself uses 32-bit NPT). */ if (!tdp_enabled) set_memory_decrypted((unsigned long)mmu->pae_root, 1); else WARN_ON_ONCE(shadow_me_mask); for (i = 0; i < 4; ++i) mmu->pae_root[i] = INVALID_PAE_ROOT; return 0; } int kvm_mmu_create(struct kvm_vcpu *vcpu) { int ret; vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache; vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO; vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache; vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO; vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; vcpu->arch.nested_mmu.translate_gpa = translate_nested_gpa; ret = __kvm_mmu_create(vcpu, &vcpu->arch.guest_mmu); if (ret) return ret; ret = __kvm_mmu_create(vcpu, &vcpu->arch.root_mmu); if (ret) goto fail_allocate_root; return ret; fail_allocate_root: free_mmu_pages(&vcpu->arch.guest_mmu); return ret; } #define BATCH_ZAP_PAGES 10 static void kvm_zap_obsolete_pages(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; int nr_zapped, batch = 0; restart: list_for_each_entry_safe_reverse(sp, node, &kvm->arch.active_mmu_pages, link) { /* * No obsolete valid page exists before a newly created page * since active_mmu_pages is a FIFO list. */ if (!is_obsolete_sp(kvm, sp)) break; /* * Invalid pages should never land back on the list of active * pages. Skip the bogus page, otherwise we'll get stuck in an * infinite loop if the page gets put back on the list (again). */ if (WARN_ON(sp->role.invalid)) continue; /* * No need to flush the TLB since we're only zapping shadow * pages with an obsolete generation number and all vCPUS have * loaded a new root, i.e. the shadow pages being zapped cannot * be in active use by the guest. */ if (batch >= BATCH_ZAP_PAGES && cond_resched_rwlock_write(&kvm->mmu_lock)) { batch = 0; goto restart; } if (__kvm_mmu_prepare_zap_page(kvm, sp, &kvm->arch.zapped_obsolete_pages, &nr_zapped)) { batch += nr_zapped; goto restart; } } /* * Trigger a remote TLB flush before freeing the page tables to ensure * KVM is not in the middle of a lockless shadow page table walk, which * may reference the pages. */ kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); } /* * Fast invalidate all shadow pages and use lock-break technique * to zap obsolete pages. * * It's required when memslot is being deleted or VM is being * destroyed, in these cases, we should ensure that KVM MMU does * not use any resource of the being-deleted slot or all slots * after calling the function. */ static void kvm_mmu_zap_all_fast(struct kvm *kvm) { lockdep_assert_held(&kvm->slots_lock); write_lock(&kvm->mmu_lock); trace_kvm_mmu_zap_all_fast(kvm); /* * Toggle mmu_valid_gen between '0' and '1'. Because slots_lock is * held for the entire duration of zapping obsolete pages, it's * impossible for there to be multiple invalid generations associated * with *valid* shadow pages at any given time, i.e. there is exactly * one valid generation and (at most) one invalid generation. */ kvm->arch.mmu_valid_gen = kvm->arch.mmu_valid_gen ? 0 : 1; /* In order to ensure all threads see this change when * handling the MMU reload signal, this must happen in the * same critical section as kvm_reload_remote_mmus, and * before kvm_zap_obsolete_pages as kvm_zap_obsolete_pages * could drop the MMU lock and yield. */ if (is_tdp_mmu_enabled(kvm)) kvm_tdp_mmu_invalidate_all_roots(kvm); /* * Notify all vcpus to reload its shadow page table and flush TLB. * Then all vcpus will switch to new shadow page table with the new * mmu_valid_gen. * * Note: we need to do this under the protection of mmu_lock, * otherwise, vcpu would purge shadow page but miss tlb flush. */ kvm_reload_remote_mmus(kvm); kvm_zap_obsolete_pages(kvm); write_unlock(&kvm->mmu_lock); if (is_tdp_mmu_enabled(kvm)) { read_lock(&kvm->mmu_lock); kvm_tdp_mmu_zap_invalidated_roots(kvm); read_unlock(&kvm->mmu_lock); } } static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) { return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); } static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, struct kvm_memory_slot *slot, struct kvm_page_track_notifier_node *node) { kvm_mmu_zap_all_fast(kvm); } void kvm_mmu_init_vm(struct kvm *kvm) { struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; kvm_mmu_init_tdp_mmu(kvm); node->track_write = kvm_mmu_pte_write; node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot; kvm_page_track_register_notifier(kvm, node); } void kvm_mmu_uninit_vm(struct kvm *kvm) { struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; kvm_page_track_unregister_notifier(kvm, node); kvm_mmu_uninit_tdp_mmu(kvm); } void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; int i; bool flush = false; write_lock(&kvm->mmu_lock); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { slots = __kvm_memslots(kvm, i); kvm_for_each_memslot(memslot, slots) { gfn_t start, end; start = max(gfn_start, memslot->base_gfn); end = min(gfn_end, memslot->base_gfn + memslot->npages); if (start >= end) continue; flush = slot_handle_level_range(kvm, memslot, kvm_zap_rmapp, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, start, end - 1, true, flush); } } if (flush) kvm_flush_remote_tlbs_with_address(kvm, gfn_start, gfn_end); write_unlock(&kvm->mmu_lock); if (is_tdp_mmu_enabled(kvm)) { flush = false; read_lock(&kvm->mmu_lock); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, gfn_start, gfn_end, flush, true); if (flush) kvm_flush_remote_tlbs_with_address(kvm, gfn_start, gfn_end); read_unlock(&kvm->mmu_lock); } } static bool slot_rmap_write_protect(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot) { return __rmap_write_protect(kvm, rmap_head, false); } void kvm_mmu_slot_remove_write_access(struct kvm *kvm, struct kvm_memory_slot *memslot, int start_level) { bool flush; write_lock(&kvm->mmu_lock); flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect, start_level, KVM_MAX_HUGEPAGE_LEVEL, false); write_unlock(&kvm->mmu_lock); if (is_tdp_mmu_enabled(kvm)) { read_lock(&kvm->mmu_lock); flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, start_level); read_unlock(&kvm->mmu_lock); } /* * We can flush all the TLBs out of the mmu lock without TLB * corruption since we just change the spte from writable to * readonly so that we only need to care the case of changing * spte from present to present (changing the spte from present * to nonpresent will flush all the TLBs immediately), in other * words, the only case we care is mmu_spte_update() where we * have checked Host-writable | MMU-writable instead of * PT_WRITABLE_MASK, that means it does not depend on PT_WRITABLE_MASK * anymore. */ if (flush) kvm_arch_flush_remote_tlbs_memslot(kvm, memslot); } static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot) { u64 *sptep; struct rmap_iterator iter; int need_tlb_flush = 0; kvm_pfn_t pfn; struct kvm_mmu_page *sp; restart: for_each_rmap_spte(rmap_head, &iter, sptep) { sp = sptep_to_sp(sptep); pfn = spte_to_pfn(*sptep); /* * We cannot do huge page mapping for indirect shadow pages, * which are found on the last rmap (level = 1) when not using * tdp; such shadow pages are synced with the page table in * the guest, and the guest page table is using 4K page size * mapping if the indirect sp has level = 1. */ if (sp->role.direct && !kvm_is_reserved_pfn(pfn) && sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, pfn, PG_LEVEL_NUM)) { pte_list_remove(rmap_head, sptep); if (kvm_available_flush_tlb_with_range()) kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level)); else need_tlb_flush = 1; goto restart; } } return need_tlb_flush; } void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, const struct kvm_memory_slot *memslot) { /* FIXME: const-ify all uses of struct kvm_memory_slot. */ struct kvm_memory_slot *slot = (struct kvm_memory_slot *)memslot; bool flush; write_lock(&kvm->mmu_lock); flush = slot_handle_leaf(kvm, slot, kvm_mmu_zap_collapsible_spte, true); if (flush) kvm_arch_flush_remote_tlbs_memslot(kvm, slot); write_unlock(&kvm->mmu_lock); if (is_tdp_mmu_enabled(kvm)) { flush = false; read_lock(&kvm->mmu_lock); flush = kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot, flush); if (flush) kvm_arch_flush_remote_tlbs_memslot(kvm, slot); read_unlock(&kvm->mmu_lock); } } void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, const struct kvm_memory_slot *memslot) { /* * All current use cases for flushing the TLBs for a specific memslot * related to dirty logging, and many do the TLB flush out of mmu_lock. * The interaction between the various operations on memslot must be * serialized by slots_locks to ensure the TLB flush from one operation * is observed by any other operation on the same memslot. */ lockdep_assert_held(&kvm->slots_lock); kvm_flush_remote_tlbs_with_address(kvm, memslot->base_gfn, memslot->npages); } void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, struct kvm_memory_slot *memslot) { bool flush; write_lock(&kvm->mmu_lock); flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, false); write_unlock(&kvm->mmu_lock); if (is_tdp_mmu_enabled(kvm)) { read_lock(&kvm->mmu_lock); flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot); read_unlock(&kvm->mmu_lock); } /* * It's also safe to flush TLBs out of mmu lock here as currently this * function is only used for dirty logging, in which case flushing TLB * out of mmu lock also guarantees no dirty pages will be lost in * dirty_bitmap. */ if (flush) kvm_arch_flush_remote_tlbs_memslot(kvm, memslot); } void kvm_mmu_zap_all(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; LIST_HEAD(invalid_list); int ign; write_lock(&kvm->mmu_lock); restart: list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { if (WARN_ON(sp->role.invalid)) continue; if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign)) goto restart; if (cond_resched_rwlock_write(&kvm->mmu_lock)) goto restart; } kvm_mmu_commit_zap_page(kvm, &invalid_list); if (is_tdp_mmu_enabled(kvm)) kvm_tdp_mmu_zap_all(kvm); write_unlock(&kvm->mmu_lock); } void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) { WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); gen &= MMIO_SPTE_GEN_MASK; /* * Generation numbers are incremented in multiples of the number of * address spaces in order to provide unique generations across all * address spaces. Strip what is effectively the address space * modifier prior to checking for a wrap of the MMIO generation so * that a wrap in any address space is detected. */ gen &= ~((u64)KVM_ADDRESS_SPACE_NUM - 1); /* * The very rare case: if the MMIO generation number has wrapped, * zap all shadow pages. */ if (unlikely(gen == 0)) { kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n"); kvm_mmu_zap_all_fast(kvm); } } static unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) { struct kvm *kvm; int nr_to_scan = sc->nr_to_scan; unsigned long freed = 0; mutex_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) { int idx; LIST_HEAD(invalid_list); /* * Never scan more than sc->nr_to_scan VM instances. * Will not hit this condition practically since we do not try * to shrink more than one VM and it is very unlikely to see * !n_used_mmu_pages so many times. */ if (!nr_to_scan--) break; /* * n_used_mmu_pages is accessed without holding kvm->mmu_lock * here. We may skip a VM instance errorneosly, but we do not * want to shrink a VM that only started to populate its MMU * anyway. */ if (!kvm->arch.n_used_mmu_pages && !kvm_has_zapped_obsolete_pages(kvm)) continue; idx = srcu_read_lock(&kvm->srcu); write_lock(&kvm->mmu_lock); if (kvm_has_zapped_obsolete_pages(kvm)) { kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); goto unlock; } freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan); unlock: write_unlock(&kvm->mmu_lock); srcu_read_unlock(&kvm->srcu, idx); /* * unfair on small ones * per-vm shrinkers cry out * sadness comes quickly */ list_move_tail(&kvm->vm_list, &vm_list); break; } mutex_unlock(&kvm_lock); return freed; } static unsigned long mmu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { return percpu_counter_read_positive(&kvm_total_used_mmu_pages); } static struct shrinker mmu_shrinker = { .count_objects = mmu_shrink_count, .scan_objects = mmu_shrink_scan, .seeks = DEFAULT_SEEKS * 10, }; static void mmu_destroy_caches(void) { kmem_cache_destroy(pte_list_desc_cache); kmem_cache_destroy(mmu_page_header_cache); } static bool get_nx_auto_mode(void) { /* Return true when CPU has the bug, and mitigations are ON */ return boot_cpu_has_bug(X86_BUG_ITLB_MULTIHIT) && !cpu_mitigations_off(); } static void __set_nx_huge_pages(bool val) { nx_huge_pages = itlb_multihit_kvm_mitigation = val; } static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) { bool old_val = nx_huge_pages; bool new_val; /* In "auto" mode deploy workaround only if CPU has the bug. */ if (sysfs_streq(val, "off")) new_val = 0; else if (sysfs_streq(val, "force")) new_val = 1; else if (sysfs_streq(val, "auto")) new_val = get_nx_auto_mode(); else if (strtobool(val, &new_val) < 0) return -EINVAL; __set_nx_huge_pages(new_val); if (new_val != old_val) { struct kvm *kvm; mutex_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) { mutex_lock(&kvm->slots_lock); kvm_mmu_zap_all_fast(kvm); mutex_unlock(&kvm->slots_lock); wake_up_process(kvm->arch.nx_lpage_recovery_thread); } mutex_unlock(&kvm_lock); } return 0; } int kvm_mmu_module_init(void) { int ret = -ENOMEM; if (nx_huge_pages == -1) __set_nx_huge_pages(get_nx_auto_mode()); /* * MMU roles use union aliasing which is, generally speaking, an * undefined behavior. However, we supposedly know how compilers behave * and the current status quo is unlikely to change. Guardians below are * supposed to let us know if the assumption becomes false. */ BUILD_BUG_ON(sizeof(union kvm_mmu_page_role) != sizeof(u32)); BUILD_BUG_ON(sizeof(union kvm_mmu_extended_role) != sizeof(u32)); BUILD_BUG_ON(sizeof(union kvm_mmu_role) != sizeof(u64)); kvm_mmu_reset_all_pte_masks(); pte_list_desc_cache = kmem_cache_create("pte_list_desc", sizeof(struct pte_list_desc), 0, SLAB_ACCOUNT, NULL); if (!pte_list_desc_cache) goto out; mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header", sizeof(struct kvm_mmu_page), 0, SLAB_ACCOUNT, NULL); if (!mmu_page_header_cache) goto out; if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL)) goto out; ret = register_shrinker(&mmu_shrinker); if (ret) goto out; return 0; out: mmu_destroy_caches(); return ret; } /* * Calculate mmu pages needed for kvm. */ unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm) { unsigned long nr_mmu_pages; unsigned long nr_pages = 0; struct kvm_memslots *slots; struct kvm_memory_slot *memslot; int i; for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { slots = __kvm_memslots(kvm, i); kvm_for_each_memslot(memslot, slots) nr_pages += memslot->npages; } nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000; nr_mmu_pages = max(nr_mmu_pages, KVM_MIN_ALLOC_MMU_PAGES); return nr_mmu_pages; } void kvm_mmu_destroy(struct kvm_vcpu *vcpu) { kvm_mmu_unload(vcpu); free_mmu_pages(&vcpu->arch.root_mmu); free_mmu_pages(&vcpu->arch.guest_mmu); mmu_free_memory_caches(vcpu); } void kvm_mmu_module_exit(void) { mmu_destroy_caches(); percpu_counter_destroy(&kvm_total_used_mmu_pages); unregister_shrinker(&mmu_shrinker); mmu_audit_disable(); } static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp) { unsigned int old_val; int err; old_val = nx_huge_pages_recovery_ratio; err = param_set_uint(val, kp); if (err) return err; if (READ_ONCE(nx_huge_pages) && !old_val && nx_huge_pages_recovery_ratio) { struct kvm *kvm; mutex_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) wake_up_process(kvm->arch.nx_lpage_recovery_thread); mutex_unlock(&kvm_lock); } return err; } static void kvm_recover_nx_lpages(struct kvm *kvm) { int rcu_idx; struct kvm_mmu_page *sp; unsigned int ratio; LIST_HEAD(invalid_list); bool flush = false; ulong to_zap; rcu_idx = srcu_read_lock(&kvm->srcu); write_lock(&kvm->mmu_lock); ratio = READ_ONCE(nx_huge_pages_recovery_ratio); to_zap = ratio ? DIV_ROUND_UP(kvm->stat.nx_lpage_splits, ratio) : 0; for ( ; to_zap; --to_zap) { if (list_empty(&kvm->arch.lpage_disallowed_mmu_pages)) break; /* * We use a separate list instead of just using active_mmu_pages * because the number of lpage_disallowed pages is expected to * be relatively small compared to the total. */ sp = list_first_entry(&kvm->arch.lpage_disallowed_mmu_pages, struct kvm_mmu_page, lpage_disallowed_link); WARN_ON_ONCE(!sp->lpage_disallowed); if (is_tdp_mmu_page(sp)) { flush |= kvm_tdp_mmu_zap_sp(kvm, sp); } else { kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); WARN_ON_ONCE(sp->lpage_disallowed); } if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); cond_resched_rwlock_write(&kvm->mmu_lock); flush = false; } } kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); write_unlock(&kvm->mmu_lock); srcu_read_unlock(&kvm->srcu, rcu_idx); } static long get_nx_lpage_recovery_timeout(u64 start_time) { return READ_ONCE(nx_huge_pages) && READ_ONCE(nx_huge_pages_recovery_ratio) ? start_time + 60 * HZ - get_jiffies_64() : MAX_SCHEDULE_TIMEOUT; } static int kvm_nx_lpage_recovery_worker(struct kvm *kvm, uintptr_t data) { u64 start_time; long remaining_time; while (true) { start_time = get_jiffies_64(); remaining_time = get_nx_lpage_recovery_timeout(start_time); set_current_state(TASK_INTERRUPTIBLE); while (!kthread_should_stop() && remaining_time > 0) { schedule_timeout(remaining_time); remaining_time = get_nx_lpage_recovery_timeout(start_time); set_current_state(TASK_INTERRUPTIBLE); } set_current_state(TASK_RUNNING); if (kthread_should_stop()) return 0; kvm_recover_nx_lpages(kvm); } } int kvm_mmu_post_init_vm(struct kvm *kvm) { int err; err = kvm_vm_create_worker_thread(kvm, kvm_nx_lpage_recovery_worker, 0, "kvm-nx-lpage-recovery", &kvm->arch.nx_lpage_recovery_thread); if (!err) kthread_unpark(kvm->arch.nx_lpage_recovery_thread); return err; } void kvm_mmu_pre_destroy_vm(struct kvm *kvm) { if (kvm->arch.nx_lpage_recovery_thread) kthread_stop(kvm->arch.nx_lpage_recovery_thread); }
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with Cregit http://github.com/cregit/cregit
Version 2.0-RC1