| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Xiao Guangrong | 6983 | 27.82% | 129 | 21.22% |
| Avi Kivity | 3725 | 14.84% | 111 | 18.26% |
| Marcelo Tosatti | 2664 | 10.61% | 38 | 6.25% |
| Junaid Shahid | 2154 | 8.58% | 28 | 4.61% |
| Takuya Yoshikawa | 1382 | 5.51% | 49 | 8.06% |
| Joerg Roedel | 1307 | 5.21% | 24 | 3.95% |
| Paolo Bonzini | 1103 | 4.39% | 42 | 6.91% |
| Vitaly Kuznetsov | 637 | 2.54% | 7 | 1.15% |
| Kai Huang | 580 | 2.31% | 7 | 1.15% |
| Andrea Arcangeli | 536 | 2.14% | 4 | 0.66% |
| Wanpeng Li | 414 | 1.65% | 7 | 1.15% |
| Eddie Dong | 399 | 1.59% | 7 | 1.15% |
| Peter Feiner | 348 | 1.39% | 4 | 0.66% |
| Izik Eidus | 302 | 1.20% | 6 | 0.99% |
| Gleb Natapov | 302 | 1.20% | 13 | 2.14% |
| Huaitong Han | 239 | 0.95% | 1 | 0.16% |
| Yang Zhang | 236 | 0.94% | 2 | 0.33% |
| Brijesh Singh | 175 | 0.70% | 4 | 0.66% |
| Yu Zhang | 137 | 0.55% | 2 | 0.33% |
| Lai Jiangshan | 128 | 0.51% | 3 | 0.49% |
| Nadav Har'El | 111 | 0.44% | 3 | 0.49% |
| Sheng Yang | 106 | 0.42% | 7 | 1.15% |
| Xiantao Zhang | 100 | 0.40% | 4 | 0.66% |
| Dave Hansen | 71 | 0.28% | 4 | 0.66% |
| Wei Yang | 69 | 0.27% | 3 | 0.49% |
| Huang Ying | 67 | 0.27% | 2 | 0.33% |
| David Matlack | 66 | 0.26% | 4 | 0.66% |
| Andres Lagar-Cavilla | 64 | 0.25% | 2 | 0.33% |
| Tom Lendacky | 55 | 0.22% | 3 | 0.49% |
| Bandan Das | 53 | 0.21% | 6 | 0.99% |
| Davidlohr Bueso A | 47 | 0.19% | 2 | 0.33% |
| David Chinner | 46 | 0.18% | 2 | 0.33% |
| Jim Mattson | 45 | 0.18% | 2 | 0.33% |
| Sean Christopherson | 45 | 0.18% | 4 | 0.66% |
| Nadav Amit | 42 | 0.17% | 3 | 0.49% |
| Xiaoguang Chen | 27 | 0.11% | 1 | 0.16% |
| Lan Tianyu | 26 | 0.10% | 5 | 0.82% |
| Haozhong Zhang | 23 | 0.09% | 2 | 0.33% |
| Anthony Liguori | 22 | 0.09% | 3 | 0.49% |
| Arnd Bergmann | 20 | 0.08% | 1 | 0.16% |
| Dan J Williams | 18 | 0.07% | 1 | 0.16% |
| Feng Wu | 18 | 0.07% | 2 | 0.33% |
| Ladi Prosek | 16 | 0.06% | 2 | 0.33% |
| Wei Yongjun | 16 | 0.06% | 3 | 0.49% |
| Liang Chen | 13 | 0.05% | 2 | 0.33% |
| Andre Przywara | 12 | 0.05% | 2 | 0.33% |
| Ingo Molnar | 12 | 0.05% | 4 | 0.66% |
| Ying Han | 11 | 0.04% | 1 | 0.16% |
| Jike Song | 10 | 0.04% | 1 | 0.16% |
| Xiaotian Feng | 10 | 0.04% | 1 | 0.16% |
| Frederik Deweerdt | 10 | 0.04% | 1 | 0.16% |
| Radim Krčmář | 6 | 0.02% | 1 | 0.16% |
| Gui Jianfeng | 6 | 0.02% | 2 | 0.33% |
| Hillf Danton | 6 | 0.02% | 1 | 0.16% |
| Tiejun Chen | 5 | 0.02% | 2 | 0.33% |
| David Woodhouse | 5 | 0.02% | 1 | 0.16% |
| Eric Northup | 5 | 0.02% | 1 | 0.16% |
| Tejun Heo | 5 | 0.02% | 2 | 0.33% |
| Zhao Jin | 4 | 0.02% | 1 | 0.16% |
| Christoffer Dall | 4 | 0.02% | 1 | 0.16% |
| Dominik Dingel | 4 | 0.02% | 1 | 0.16% |
| Eric W. Biedermann | 4 | 0.02% | 2 | 0.33% |
| Paul Gortmaker | 4 | 0.02% | 1 | 0.16% |
| Harvey Harrison | 4 | 0.02% | 1 | 0.16% |
| Borislav Petkov | 4 | 0.02% | 1 | 0.16% |
| Yu Zhao | 3 | 0.01% | 1 | 0.16% |
| Eduardo Pereira Habkost | 3 | 0.01% | 1 | 0.16% |
| Shakeel Butt | 3 | 0.01% | 2 | 0.33% |
| Michael S. Tsirkin | 3 | 0.01% | 1 | 0.16% |
| Hannes Eder | 3 | 0.01% | 1 | 0.16% |
| Hao Peng | 2 | 0.01% | 1 | 0.16% |
| Geliang Tang | 2 | 0.01% | 1 | 0.16% |
| Mike Day | 2 | 0.01% | 1 | 0.16% |
| Boqun Feng | 2 | 0.01% | 1 | 0.16% |
| Ard Biesheuvel | 2 | 0.01% | 1 | 0.16% |
| Xudong Hao | 2 | 0.01% | 2 | 0.33% |
| Mark Rutland | 2 | 0.01% | 1 | 0.16% |
| Gimcuan Hui | 1 | 0.00% | 1 | 0.16% |
| Adam Buchbinder | 1 | 0.00% | 1 | 0.16% |
| Nicolas Kaiser | 1 | 0.00% | 1 | 0.16% |
| David Hildenbrand | 1 | 0.00% | 1 | 0.16% |
| Jan Kiszka | 1 | 0.00% | 1 | 0.16% |
| Total | 25102 | 608 |
/* * 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> * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * */ #include "irq.h" #include "mmu.h" #include "x86.h" #include "kvm_cache_regs.h" #include "cpuid.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 <asm/page.h> #include <asm/pat.h> #include <asm/cmpxchg.h> #include <asm/io.h> #include <asm/vmx.h> #include <asm/kvm_page_track.h> #include "trace.h" /* * 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; enum { AUDIT_PRE_PAGE_FAULT, AUDIT_POST_PAGE_FAULT, AUDIT_PRE_PTE_WRITE, AUDIT_POST_PTE_WRITE, AUDIT_PRE_SYNC, AUDIT_POST_SYNC }; #undef MMU_DEBUG #ifdef MMU_DEBUG static bool dbg = 0; module_param(dbg, bool, 0644); #define pgprintk(x...) do { if (dbg) printk(x); } while (0) #define rmap_printk(x...) do { if (dbg) printk(x); } while (0) #define MMU_WARN_ON(x) WARN_ON(x) #else #define pgprintk(x...) do { } while (0) #define rmap_printk(x...) do { } while (0) #define MMU_WARN_ON(x) do { } while (0) #endif #define PTE_PREFETCH_NUM 8 #define PT_FIRST_AVAIL_BITS_SHIFT 10 #define PT64_SECOND_AVAIL_BITS_SHIFT 52 #define PT64_LEVEL_BITS 9 #define PT64_LEVEL_SHIFT(level) \ (PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS) #define PT64_INDEX(address, level)\ (((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1)) #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 PT64_BASE_ADDR_MASK __sme_clr((((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))) #define PT64_DIR_BASE_ADDR_MASK \ (PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1)) #define PT64_LVL_ADDR_MASK(level) \ (PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \ * PT64_LEVEL_BITS))) - 1)) #define PT64_LVL_OFFSET_MASK(level) \ (PT64_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \ * PT64_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)) #define PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \ | shadow_x_mask | shadow_nx_mask | shadow_me_mask) #define ACC_EXEC_MASK 1 #define ACC_WRITE_MASK PT_WRITABLE_MASK #define ACC_USER_MASK PT_USER_MASK #define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK) /* The mask for the R/X bits in EPT PTEs */ #define PT64_EPT_READABLE_MASK 0x1ull #define PT64_EPT_EXECUTABLE_MASK 0x4ull #include <trace/events/kvm.h> #define CREATE_TRACE_POINTS #include "mmutrace.h" #define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) #define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1)) #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) /* make pte_list_desc fit well in cache line */ #define PTE_LIST_EXT 3 /* * Return values of handle_mmio_page_fault and mmu.page_fault: * RET_PF_RETRY: let CPU fault again on the address. * RET_PF_EMULATE: mmio page fault, emulate the instruction directly. * * For handle_mmio_page_fault only: * RET_PF_INVALID: the spte is invalid, let the real page fault path update it. */ enum { RET_PF_RETRY = 0, RET_PF_EMULATE = 1, RET_PF_INVALID = 2, }; 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; }; static const union kvm_mmu_page_role mmu_base_role_mask = { .cr0_wp = 1, .cr4_pae = 1, .nxe = 1, .smep_andnot_wp = 1, .smap_andnot_wp = 1, .smm = 1, .guest_mode = 1, .ad_disabled = 1, }; #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; static struct kmem_cache *mmu_page_header_cache; static struct percpu_counter kvm_total_used_mmu_pages; static u64 __read_mostly shadow_nx_mask; static u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ static u64 __read_mostly shadow_user_mask; static u64 __read_mostly shadow_accessed_mask; static u64 __read_mostly shadow_dirty_mask; static u64 __read_mostly shadow_mmio_mask; static u64 __read_mostly shadow_mmio_value; static u64 __read_mostly shadow_present_mask; static u64 __read_mostly shadow_me_mask; /* * SPTEs used by MMUs without A/D bits are marked with shadow_acc_track_value. * Non-present SPTEs with shadow_acc_track_value set are in place for access * tracking. */ static u64 __read_mostly shadow_acc_track_mask; static const u64 shadow_acc_track_value = SPTE_SPECIAL_MASK; /* * The mask/shift to use for saving the original R/X bits when marking the PTE * as not-present for access tracking purposes. We do not save the W bit as the * PTEs being access tracked also need to be dirty tracked, so the W bit will be * restored only when a write is attempted to the page. */ static const u64 shadow_acc_track_saved_bits_mask = PT64_EPT_READABLE_MASK | PT64_EPT_EXECUTABLE_MASK; static const u64 shadow_acc_track_saved_bits_shift = PT64_SECOND_AVAIL_BITS_SHIFT; /* * This mask must be set on all non-zero Non-Present or Reserved SPTEs in order * to guard against L1TF attacks. */ static u64 __read_mostly shadow_nonpresent_or_rsvd_mask; /* * The number of high-order 1 bits to use in the mask above. */ static const u64 shadow_nonpresent_or_rsvd_mask_len = 5; /* * In some cases, we need to preserve the GFN of a non-present or reserved * SPTE when we usurp the upper five bits of the physical address space to * defend against L1TF, e.g. for MMIO SPTEs. To preserve the GFN, we'll * shift bits of the GFN that overlap with shadow_nonpresent_or_rsvd_mask * left into the reserved bits, i.e. the GFN in the SPTE will be split into * high and low parts. This mask covers the lower bits of the GFN. */ static u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask; 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); void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value) { BUG_ON((mmio_mask & mmio_value) != mmio_value); shadow_mmio_value = mmio_value | SPTE_SPECIAL_MASK; shadow_mmio_mask = mmio_mask | SPTE_SPECIAL_MASK; } EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask); static inline bool sp_ad_disabled(struct kvm_mmu_page *sp) { return sp->role.ad_disabled; } static inline bool spte_ad_enabled(u64 spte) { MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value); return !(spte & shadow_acc_track_value); } static inline u64 spte_shadow_accessed_mask(u64 spte) { MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value); return spte_ad_enabled(spte) ? shadow_accessed_mask : 0; } static inline u64 spte_shadow_dirty_mask(u64 spte) { MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value); return spte_ad_enabled(spte) ? shadow_dirty_mask : 0; } static inline bool is_access_track_spte(u64 spte) { return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0; } /* * the low bit of the generation number is always presumed to be zero. * This disables mmio caching during memslot updates. The concept is * similar to a seqcount but instead of retrying the access we just punt * and ignore the cache. * * spte bits 3-11 are used as bits 1-9 of the generation number, * the bits 52-61 are used as bits 10-19 of the generation number. */ #define MMIO_SPTE_GEN_LOW_SHIFT 2 #define MMIO_SPTE_GEN_HIGH_SHIFT 52 #define MMIO_GEN_SHIFT 20 #define MMIO_GEN_LOW_SHIFT 10 #define MMIO_GEN_LOW_MASK ((1 << MMIO_GEN_LOW_SHIFT) - 2) #define MMIO_GEN_MASK ((1 << MMIO_GEN_SHIFT) - 1) static u64 generation_mmio_spte_mask(unsigned int gen) { u64 mask; WARN_ON(gen & ~MMIO_GEN_MASK); mask = (gen & MMIO_GEN_LOW_MASK) << MMIO_SPTE_GEN_LOW_SHIFT; mask |= ((u64)gen >> MMIO_GEN_LOW_SHIFT) << MMIO_SPTE_GEN_HIGH_SHIFT; return mask; } static unsigned int get_mmio_spte_generation(u64 spte) { unsigned int gen; spte &= ~shadow_mmio_mask; gen = (spte >> MMIO_SPTE_GEN_LOW_SHIFT) & MMIO_GEN_LOW_MASK; gen |= (spte >> MMIO_SPTE_GEN_HIGH_SHIFT) << MMIO_GEN_LOW_SHIFT; return gen; } static unsigned int kvm_current_mmio_generation(struct kvm_vcpu *vcpu) { return kvm_vcpu_memslots(vcpu)->generation & MMIO_GEN_MASK; } static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, unsigned access) { unsigned int gen = kvm_current_mmio_generation(vcpu); u64 mask = generation_mmio_spte_mask(gen); u64 gpa = gfn << PAGE_SHIFT; access &= ACC_WRITE_MASK | ACC_USER_MASK; mask |= shadow_mmio_value | access; mask |= gpa | shadow_nonpresent_or_rsvd_mask; mask |= (gpa & shadow_nonpresent_or_rsvd_mask) << shadow_nonpresent_or_rsvd_mask_len; trace_mark_mmio_spte(sptep, gfn, access, gen); mmu_spte_set(sptep, mask); } static bool is_mmio_spte(u64 spte) { return (spte & shadow_mmio_mask) == shadow_mmio_value; } 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) { u64 mask = generation_mmio_spte_mask(MMIO_GEN_MASK) | shadow_mmio_mask; return (spte & ~mask) & ~PAGE_MASK; } static bool set_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, kvm_pfn_t pfn, unsigned access) { if (unlikely(is_noslot_pfn(pfn))) { mark_mmio_spte(vcpu, sptep, gfn, access); return true; } return false; } static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) { unsigned int kvm_gen, spte_gen; kvm_gen = kvm_current_mmio_generation(vcpu); spte_gen = get_mmio_spte_generation(spte); trace_check_mmio_spte(spte, kvm_gen, spte_gen); return likely(kvm_gen == spte_gen); } /* * Sets the shadow PTE masks used by the MMU. * * Assumptions: * - Setting either @accessed_mask or @dirty_mask requires setting both * - At least one of @accessed_mask or @acc_track_mask must be set */ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, u64 dirty_mask, u64 nx_mask, u64 x_mask, u64 p_mask, u64 acc_track_mask, u64 me_mask) { BUG_ON(!dirty_mask != !accessed_mask); BUG_ON(!accessed_mask && !acc_track_mask); BUG_ON(acc_track_mask & shadow_acc_track_value); shadow_user_mask = user_mask; shadow_accessed_mask = accessed_mask; shadow_dirty_mask = dirty_mask; shadow_nx_mask = nx_mask; shadow_x_mask = x_mask; shadow_present_mask = p_mask; shadow_acc_track_mask = acc_track_mask; shadow_me_mask = me_mask; } EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes); static void kvm_mmu_reset_all_pte_masks(void) { u8 low_phys_bits; shadow_user_mask = 0; shadow_accessed_mask = 0; shadow_dirty_mask = 0; shadow_nx_mask = 0; shadow_x_mask = 0; shadow_mmio_mask = 0; shadow_present_mask = 0; shadow_acc_track_mask = 0; /* * If the CPU has 46 or less physical address bits, then set an * appropriate mask to guard against L1TF attacks. Otherwise, it is * assumed that the CPU is not vulnerable to L1TF. */ low_phys_bits = boot_cpu_data.x86_phys_bits; if (boot_cpu_data.x86_phys_bits < 52 - shadow_nonpresent_or_rsvd_mask_len) { shadow_nonpresent_or_rsvd_mask = rsvd_bits(boot_cpu_data.x86_phys_bits - shadow_nonpresent_or_rsvd_mask_len, boot_cpu_data.x86_phys_bits - 1); low_phys_bits -= shadow_nonpresent_or_rsvd_mask_len; } shadow_nonpresent_or_rsvd_lower_gfn_mask = GENMASK_ULL(low_phys_bits - 1, PAGE_SHIFT); } static int is_cpuid_PSE36(void) { return 1; } static int is_nx(struct kvm_vcpu *vcpu) { return vcpu->arch.efer & EFER_NX; } static int is_shadow_present_pte(u64 pte) { return (pte != 0) && !is_mmio_spte(pte); } static int is_large_pte(u64 pte) { return pte & PT_PAGE_SIZE_MASK; } static int is_last_spte(u64 pte, int level) { if (level == PT_PAGE_TABLE_LEVEL) return 1; if (is_large_pte(pte)) return 1; return 0; } static bool is_executable_pte(u64 spte) { return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask; } static kvm_pfn_t spte_to_pfn(u64 pte) { return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT; } 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 = page_header(__pa(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(arch/x86/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 = page_header(__pa(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_can_locklessly_be_made_writable(u64 spte) { return (spte & (SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE)) == (SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE); } 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; } static bool is_accessed_spte(u64 spte) { u64 accessed_mask = spte_shadow_accessed_mask(spte); return accessed_mask ? spte & accessed_mask : !is_access_track_spte(spte); } static bool is_dirty_spte(u64 spte) { u64 dirty_mask = spte_shadow_dirty_mask(spte); return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; } /* 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); } static u64 mark_spte_for_access_track(u64 spte) { if (spte_ad_enabled(spte)) return spte & ~shadow_accessed_mask; if (is_access_track_spte(spte)) return spte; /* * Making an Access Tracking PTE will result in removal of write access * from the PTE. So, verify that we will be able to restore the write * access in the fast page fault path later on. */ WARN_ONCE((spte & PT_WRITABLE_MASK) && !spte_can_locklessly_be_made_writable(spte), "kvm: Writable SPTE is not locklessly dirty-trackable\n"); WARN_ONCE(spte & (shadow_acc_track_saved_bits_mask << shadow_acc_track_saved_bits_shift), "kvm: Access Tracking saved bit locations are not zero\n"); spte |= (spte & shadow_acc_track_saved_bits_mask) << shadow_acc_track_saved_bits_shift; spte &= ~shadow_acc_track_mask; return spte; } /* 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_cache(struct kvm_mmu_memory_cache *cache, struct kmem_cache *base_cache, int min) { void *obj; if (cache->nobjs >= min) return 0; while (cache->nobjs < ARRAY_SIZE(cache->objects)) { obj = kmem_cache_zalloc(base_cache, GFP_KERNEL); if (!obj) return cache->nobjs >= min ? 0 : -ENOMEM; cache->objects[cache->nobjs++] = obj; } return 0; } static int mmu_memory_cache_free_objects(struct kvm_mmu_memory_cache *cache) { return cache->nobjs; } static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc, struct kmem_cache *cache) { while (mc->nobjs) kmem_cache_free(cache, mc->objects[--mc->nobjs]); } static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache, int min) { void *page; if (cache->nobjs >= min) return 0; while (cache->nobjs < ARRAY_SIZE(cache->objects)) { page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT); if (!page) return cache->nobjs >= min ? 0 : -ENOMEM; cache->objects[cache->nobjs++] = page; } return 0; } static void mmu_free_memory_cache_page(struct kvm_mmu_memory_cache *mc) { while (mc->nobjs) free_page((unsigned long)mc->objects[--mc->nobjs]); } static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu) { int r; r = mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache, pte_list_desc_cache, 8 + PTE_PREFETCH_NUM); if (r) goto out; r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8); if (r) goto out; r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, mmu_page_header_cache, 4); out: return r; } static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) { mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache, pte_list_desc_cache); mmu_free_memory_cache_page(&vcpu->arch.mmu_page_cache); mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache, mmu_page_header_cache); } static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc) { void *p; BUG_ON(!mc->nobjs); p = mc->objects[--mc->nobjs]; return p; } static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu) { return 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) BUG_ON(gfn != kvm_mmu_page_get_gfn(sp, index)); else sp->gfns[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, 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 = PT_DIRECTORY_LEVEL; i <= PT_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 > PT_PAGE_TABLE_LEVEL) return kvm_slot_page_track_add_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); kvm_mmu_gfn_disallow_lpage(slot, gfn); } 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 > PT_PAGE_TABLE_LEVEL) return kvm_slot_page_track_remove_page(kvm, slot, gfn, KVM_PAGE_TRACK_WRITE); kvm_mmu_gfn_allow_lpage(slot, gfn); } static bool __mmu_gfn_lpage_is_disallowed(gfn_t gfn, int level, struct kvm_memory_slot *slot) { struct kvm_lpage_info *linfo; if (slot) { linfo = lpage_info_slot(gfn, slot, level); return !!linfo->disallow_lpage; } return true; } static bool mmu_gfn_lpage_is_disallowed(struct kvm_vcpu *vcpu, gfn_t gfn, int level) { struct kvm_memory_slot *slot; slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); return __mmu_gfn_lpage_is_disallowed(gfn, level, slot); } static int host_mapping_level(struct kvm *kvm, gfn_t gfn) { unsigned long page_size; int i, ret = 0; page_size = kvm_host_page_size(kvm, gfn); for (i = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) { if (page_size >= KVM_HPAGE_SIZE(i)) ret = i; else break; } return ret; } static inline bool memslot_valid_for_gpte(struct kvm_memory_slot *slot, bool no_dirty_log) { if (!slot || slot->flags & KVM_MEMSLOT_INVALID) return false; if (no_dirty_log && slot->dirty_bitmap) return false; return true; } 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 (!memslot_valid_for_gpte(slot, no_dirty_log)) slot = NULL; return slot; } static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn, bool *force_pt_level) { int host_level, level, max_level; struct kvm_memory_slot *slot; if (unlikely(*force_pt_level)) return PT_PAGE_TABLE_LEVEL; slot = kvm_vcpu_gfn_to_memslot(vcpu, large_gfn); *force_pt_level = !memslot_valid_for_gpte(slot, true); if (unlikely(*force_pt_level)) return PT_PAGE_TABLE_LEVEL; host_level = host_mapping_level(vcpu->kvm, large_gfn); if (host_level == PT_PAGE_TABLE_LEVEL) return host_level; max_level = min(kvm_x86_ops->get_lpage_level(), host_level); for (level = PT_DIRECTORY_LEVEL; level <= max_level; ++level) if (__mmu_gfn_lpage_is_disallowed(large_gfn, level, slot)) break; return level - 1; } /* * 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("pte_list_add: %p %llx 0->1\n", spte, *spte); rmap_head->val = (unsigned long)spte; } else if (!(rmap_head->val & 1)) { rmap_printk("pte_list_add: %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("pte_list_add: %p %llx many->many\n", spte, *spte); desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); while (desc->sptes[PTE_LIST_EXT-1] && desc->more) { desc = desc->more; count += PTE_LIST_EXT; } if (desc->sptes[PTE_LIST_EXT-1]) { desc->more = mmu_alloc_pte_list_desc(vcpu); 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 = (unsigned long)desc->sptes[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("%s: %p 1->0\n", __func__, spte); if ((u64 *)rmap_head->val != spte) { pr_err("%s: %p 1->BUG\n", __func__, spte); BUG(); } rmap_head->val = 0; } else { rmap_printk("%s: %p many->many\n", __func__, 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 - PT_PAGE_TABLE_LEVEL][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 *cache; cache = &vcpu->arch.mmu_pte_list_desc_cache; return mmu_memory_cache_free_objects(cache); } 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 = page_header(__pa(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 = page_header(__pa(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 itererator 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(page_header(__pa(sptep))->role.level == PT_PAGE_TABLE_LEVEL); 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)) kvm_flush_remote_tlbs(vcpu->kvm); } /* * 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("rmap_write_protect: spte %p %llx\n", sptep, *sptep); if (pt_protect) spte &= ~SPTE_MMU_WRITEABLE; 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("rmap_clear_dirty: spte %p %llx\n", sptep, *sptep); spte &= ~shadow_dirty_mask; return mmu_spte_update(sptep, spte); } static bool wrprot_ad_disabled_spte(u64 *sptep) { bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, (unsigned long *)sptep); if (was_writable) 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) { u64 *sptep; struct rmap_iterator iter; bool flush = false; for_each_rmap_spte(rmap_head, &iter, sptep) if (spte_ad_enabled(*sptep)) flush |= spte_clear_dirty(sptep); else flush |= wrprot_ad_disabled_spte(sptep); return flush; } static bool spte_set_dirty(u64 *sptep) { u64 spte = *sptep; rmap_printk("rmap_set_dirty: spte %p %llx\n", sptep, *sptep); spte |= shadow_dirty_mask; return mmu_spte_update(sptep, spte); } static bool __rmap_set_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head) { u64 *sptep; struct rmap_iterator iter; bool flush = false; for_each_rmap_spte(rmap_head, &iter, sptep) if (spte_ad_enabled(*sptep)) flush |= spte_set_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; while (mask) { rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PT_PAGE_TABLE_LEVEL, 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. */ 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; while (mask) { rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PT_PAGE_TABLE_LEVEL, slot); __rmap_clear_dirty(kvm, rmap_head); /* clear the first set bit */ mask &= mask - 1; } } EXPORT_SYMBOL_GPL(kvm_mmu_clear_dirty_pt_masked); /** * 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->enable_log_dirty_pt_masked) kvm_x86_ops->enable_log_dirty_pt_masked(kvm, slot, gfn_offset, mask); else kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask); } /** * kvm_arch_write_log_dirty - emulate dirty page logging * @vcpu: Guest mode vcpu * * Emulate arch specific page modification logging for the * nested hypervisor */ int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu) { if (kvm_x86_ops->write_log_dirty) return kvm_x86_ops->write_log_dirty(vcpu); return 0; } 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 = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) { rmap_head = __gfn_to_rmap(gfn, i, slot); write_protected |= __rmap_write_protect(kvm, rmap_head, true); } 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) { u64 *sptep; struct rmap_iterator iter; bool flush = false; while ((sptep = rmap_get_first(rmap_head, &iter))) { rmap_printk("%s: spte %p %llx.\n", __func__, sptep, *sptep); pte_list_remove(rmap_head, sptep); flush = true; } return flush; } static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, unsigned long data) { return kvm_zap_rmapp(kvm, rmap_head); } static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, unsigned long data) { u64 *sptep; struct rmap_iterator iter; int need_flush = 0; u64 new_spte; pte_t *ptep = (pte_t *)data; kvm_pfn_t new_pfn; WARN_ON(pte_huge(*ptep)); new_pfn = pte_pfn(*ptep); restart: for_each_rmap_spte(rmap_head, &iter, sptep) { rmap_printk("kvm_set_pte_rmapp: spte %p %llx gfn %llx (%d)\n", sptep, *sptep, gfn, level); need_flush = 1; if (pte_write(*ptep)) { pte_list_remove(rmap_head, sptep); goto restart; } else { new_spte = *sptep & ~PT64_BASE_ADDR_MASK; new_spte |= (u64)new_pfn << PAGE_SHIFT; new_spte &= ~PT_WRITABLE_MASK; new_spte &= ~SPTE_HOST_WRITEABLE; new_spte = mark_spte_for_access_track(new_spte); mmu_spte_clear_track_bits(sptep); mmu_spte_set(sptep, new_spte); } } if (need_flush) kvm_flush_remote_tlbs(kvm); return 0; } 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_)) static int kvm_handle_hva_range(struct kvm *kvm, unsigned long start, unsigned long end, unsigned long data, int (*handler)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, unsigned long data)) { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; struct slot_rmap_walk_iterator iterator; int ret = 0; int i; for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { slots = __kvm_memslots(kvm, i); kvm_for_each_memslot(memslot, slots) { unsigned long hva_start, hva_end; gfn_t gfn_start, gfn_end; hva_start = max(start, memslot->userspace_addr); hva_end = min(end, memslot->userspace_addr + (memslot->npages << PAGE_SHIFT)); if (hva_start >= hva_end) continue; /* * {gfn(page) | page intersects with [hva_start, hva_end)} = * {gfn_start, gfn_start+1, ..., gfn_end-1}. */ gfn_start = hva_to_gfn_memslot(hva_start, memslot); gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot); for_each_slot_rmap_range(memslot, PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL, gfn_start, gfn_end - 1, &iterator) ret |= handler(kvm, iterator.rmap, memslot, iterator.gfn, iterator.level, data); } } return ret; } static int kvm_handle_hva(struct kvm *kvm, unsigned long hva, unsigned long data, int (*handler)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, unsigned long data)) { return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler); } int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end) { return kvm_handle_hva_range(kvm, start, end, 0, kvm_unmap_rmapp); } void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte) { kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp); } static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, unsigned long data) { u64 *sptep; struct rmap_iterator uninitialized_var(iter); int young = 0; for_each_rmap_spte(rmap_head, &iter, sptep) young |= mmu_spte_age(sptep); trace_kvm_age_page(gfn, level, slot, young); return young; } static int kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot, gfn_t gfn, int level, unsigned long data) { 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 = page_header(__pa(spte)); rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp); kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, 0); kvm_flush_remote_tlbs(vcpu->kvm); } int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end) { return kvm_handle_hva_range(kvm, start, end, 0, kvm_age_rmapp); } int kvm_test_age_hva(struct kvm *kvm, unsigned long hva) { return kvm_handle_hva(kvm, hva, 0, kvm_test_age_rmapp); } #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, int 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 = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache); sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache); if (!direct) sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache); set_page_private(virt_to_page(sp->spt), (unsigned long)sp); /* * The active_mmu_pages list is the FIFO list, do not move the * page until it is zapped. kvm_zap_obsolete_pages depends on * this feature. See the comments in kvm_zap_obsolete_pages(). */ 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 = page_header(__pa(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; } static void nonpaging_invlpg(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root) { } static void nonpaging_update_pte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *spte, const void *pte) { WARN_ON(1); } #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 = page_header(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 int 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); /* * NOTE: we should pay more attention on the zapped-obsolete page * (is_obsolete_sp(sp) && sp->role.invalid) when you do hash list walk * since it has been deleted from active_mmu_pages but still can be found * at hast list. * * for_each_valid_sp() has skipped that kind of pages. */ #define for_each_valid_sp(_kvm, _sp, _gfn) \ hlist_for_each_entry(_sp, \ &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \ if (is_obsolete_sp((_kvm), (_sp)) || (_sp)->role.invalid) { \ } else #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ for_each_valid_sp(_kvm, _sp, _gfn) \ if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else /* @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 (sp->role.cr4_pae != !!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 void kvm_mmu_flush_or_zap(struct kvm_vcpu *vcpu, struct list_head *invalid_list, bool remote_flush, bool local_flush) { if (!list_empty(invalid_list)) { kvm_mmu_commit_zap_page(vcpu->kvm, invalid_list); return; } if (remote_flush) kvm_flush_remote_tlbs(vcpu->kvm); else if (local_flush) kvm_make_request(KVM_REQ_TLB_FLUSH, 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 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 != PT_PAGE_TABLE_LEVEL); 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 == PT_PAGE_TABLE_LEVEL) 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 == PT_PAGE_TABLE_LEVEL); 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() || spin_needbreak(&vcpu->kvm->mmu_lock)) { kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); cond_resched_lock(&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) { struct kvm_mmu_page *sp = page_header(__pa(spte)); __clear_sp_write_flooding_count(sp); } static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gaddr, unsigned level, int direct, unsigned access) { union kvm_mmu_page_role role; 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.cr4_pae = 0; role.access = access; if (!vcpu->arch.mmu->direct_map && 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; } for_each_valid_sp(vcpu->kvm, sp, gfn) { if (sp->gfn != gfn) { collisions++; continue; } if (!need_sync && sp->unsync) need_sync = true; if (sp->role.word != role.word) continue; 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, vcpu); } if (sp->unsync_children) kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); __clear_sp_write_flooding_count(sp); 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, &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]); 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 == PT_PAGE_TABLE_LEVEL && rmap_write_protect(vcpu, gfn)) kvm_flush_remote_tlbs(vcpu->kvm); if (level > PT_PAGE_TABLE_LEVEL && need_sync) flush |= kvm_sync_pages(vcpu, gfn, &invalid_list); } sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen; clear_page(sp->spt); 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 < PT_PAGE_TABLE_LEVEL) 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 = __pa(sp->spt) | shadow_present_mask | PT_WRITABLE_MASK | shadow_user_mask | shadow_x_mask | shadow_me_mask; if (sp_ad_disabled(sp)) spte |= shadow_acc_track_value; else spte |= shadow_accessed_mask; 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 = page_header(*sptep & PT64_BASE_ADDR_MASK); if (child->role.access == direct_access) return; drop_parent_pte(child, sptep); kvm_flush_remote_tlbs(vcpu->kvm); } } static bool mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *spte) { 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 = page_header(pte & PT64_BASE_ADDR_MASK); drop_parent_pte(child, spte); } return true; } if (is_mmio_spte(pte)) mmu_spte_clear_no_track(spte); return false; } static void kvm_mmu_page_unlink_children(struct kvm *kvm, struct kvm_mmu_page *sp) { unsigned i; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) mmu_page_zap_pte(kvm, sp, sp->spt + i); } 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 == PT_PAGE_TABLE_LEVEL) 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 int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, struct list_head *invalid_list) { int ret; trace_kvm_mmu_prepare_zap_page(sp); ++kvm->stat.mmu_shadow_zapped; ret = mmu_zap_unsync_children(kvm, sp, invalid_list); kvm_mmu_page_unlink_children(kvm, sp); kvm_mmu_unlink_parents(kvm, sp); 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 */ ret++; list_move(&sp->link, invalid_list); kvm_mod_used_mmu_pages(kvm, -1); } else { list_move(&sp->link, &kvm->arch.active_mmu_pages); /* * The obsolete pages can not be used on any vcpus. * See the comments in kvm_mmu_invalidate_zap_all_pages(). */ if (!sp->role.invalid && !is_obsolete_sp(kvm, sp)) kvm_reload_remote_mmus(kvm); } sp->role.invalid = 1; return ret; } 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 bool prepare_zap_oldest_mmu_page(struct kvm *kvm, struct list_head *invalid_list) { struct kvm_mmu_page *sp; if (list_empty(&kvm->arch.active_mmu_pages)) return false; sp = list_last_entry(&kvm->arch.active_mmu_pages, struct kvm_mmu_page, link); return kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); } /* * 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 int goal_nr_mmu_pages) { LIST_HEAD(invalid_list); spin_lock(&kvm->mmu_lock); if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { /* Need to free some mmu pages to achieve the goal. */ while (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) if (!prepare_zap_oldest_mmu_page(kvm, &invalid_list)) break; kvm_mmu_commit_zap_page(kvm, &invalid_list); goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; } kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; spin_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; spin_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); spin_unlock(&kvm->mmu_lock); return r; } EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page); 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); } static 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 != PT_PAGE_TABLE_LEVEL); 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 bool kvm_is_mmio_pfn(kvm_pfn_t pfn) { if (pfn_valid(pfn)) return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)) && /* * Some reserved pages, such as those from NVDIMM * DAX devices, are not for MMIO, and can be mapped * with cached memory type for better performance. * However, the above check misconceives those pages * as MMIO, and results in KVM mapping them with UC * memory type, which would hurt the performance. * Therefore, we check the host memory type in addition * and only treat UC/UC-/WC pages as MMIO. */ (!pat_enabled() || pat_pfn_immune_to_uc_mtrr(pfn)); return true; } /* Bits which may be returned by set_spte() */ #define SET_SPTE_WRITE_PROTECTED_PT BIT(0) #define SET_SPTE_NEED_REMOTE_TLB_FLUSH BIT(1) static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access, int level, gfn_t gfn, kvm_pfn_t pfn, bool speculative, bool can_unsync, bool host_writable) { u64 spte = 0; int ret = 0; struct kvm_mmu_page *sp; if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access)) return 0; sp = page_header(__pa(sptep)); if (sp_ad_disabled(sp)) spte |= shadow_acc_track_value; /* * For the EPT case, shadow_present_mask is 0 if hardware * supports exec-only page table entries. In that case, * ACC_USER_MASK and shadow_user_mask are used to represent * read access. See FNAME(gpte_access) in paging_tmpl.h. */ spte |= shadow_present_mask; if (!speculative) spte |= spte_shadow_accessed_mask(spte); if (pte_access & ACC_EXEC_MASK) spte |= shadow_x_mask; else spte |= shadow_nx_mask; if (pte_access & ACC_USER_MASK) spte |= shadow_user_mask; if (level > PT_PAGE_TABLE_LEVEL) spte |= PT_PAGE_SIZE_MASK; if (tdp_enabled) spte |= kvm_x86_ops->get_mt_mask(vcpu, gfn, kvm_is_mmio_pfn(pfn)); if (host_writable) spte |= SPTE_HOST_WRITEABLE; else pte_access &= ~ACC_WRITE_MASK; if (!kvm_is_mmio_pfn(pfn)) spte |= shadow_me_mask; spte |= (u64)pfn << PAGE_SHIFT; if (pte_access & ACC_WRITE_MASK) { /* * Other vcpu creates new sp in the window between * mapping_level() and acquiring mmu-lock. We can * allow guest to retry the access, the mapping can * be fixed if guest refault. */ if (level > PT_PAGE_TABLE_LEVEL && mmu_gfn_lpage_is_disallowed(vcpu, gfn, level)) goto done; spte |= PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE; /* * Optimization: for pte sync, if spte was writable the hash * lookup is unnecessary (and expensive). Write protection * is responsibility of mmu_get_page / kvm_sync_page. * Same reasoning can be applied to dirty page accounting. */ if (!can_unsync && is_writable_pte(*sptep)) goto set_pte; if (mmu_need_write_protect(vcpu, gfn, can_unsync)) { pgprintk("%s: found shadow page for %llx, marking ro\n", __func__, gfn); ret |= SET_SPTE_WRITE_PROTECTED_PT; pte_access &= ~ACC_WRITE_MASK; spte &= ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE); } } if (pte_access & ACC_WRITE_MASK) { kvm_vcpu_mark_page_dirty(vcpu, gfn); spte |= spte_shadow_dirty_mask(spte); } if (speculative) spte = mark_spte_for_access_track(spte); set_pte: if (mmu_spte_update(sptep, spte)) ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH; done: return ret; } static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access, int 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_RETRY; bool flush = false; pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, *sptep, write_fault, gfn); 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 > PT_PAGE_TABLE_LEVEL && !is_large_pte(*sptep)) { struct kvm_mmu_page *child; u64 pte = *sptep; child = page_header(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, vcpu); } if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush) kvm_flush_remote_tlbs(vcpu->kvm); if (unlikely(is_mmio_spte(*sptep))) ret = RET_PF_EMULATE; pgprintk("%s: setting spte %llx\n", __func__, *sptep); pgprintk("instantiating %s PTE (%s) at %llx (%llx) addr %p\n", is_large_pte(*sptep)? "2MB" : "4kB", *sptep & PT_WRITABLE_MASK ? "RW" : "R", gfn, *sptep, 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); } } kvm_release_pfn_clean(pfn); 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 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, 0, sp->role.level, gfn, page_to_pfn(pages[i]), true, true); 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 = page_header(__pa(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 > PT_PAGE_TABLE_LEVEL) return; __direct_pte_prefetch(vcpu, sp, sptep); } static int __direct_map(struct kvm_vcpu *vcpu, int write, int map_writable, int level, gfn_t gfn, kvm_pfn_t pfn, bool prefault) { struct kvm_shadow_walk_iterator iterator; struct kvm_mmu_page *sp; int emulate = 0; gfn_t pseudo_gfn; if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) return 0; for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) { if (iterator.level == level) { emulate = mmu_set_spte(vcpu, iterator.sptep, ACC_ALL, write, level, gfn, pfn, prefault, map_writable); direct_pte_prefetch(vcpu, iterator.sptep); ++vcpu->stat.pf_fixed; break; } drop_large_spte(vcpu, iterator.sptep); if (!is_shadow_present_pte(*iterator.sptep)) { u64 base_addr = iterator.addr; base_addr &= PT64_LVL_ADDR_MASK(iterator.level); pseudo_gfn = base_addr >> PAGE_SHIFT; sp = kvm_mmu_get_page(vcpu, pseudo_gfn, iterator.addr, iterator.level - 1, 1, ACC_ALL); link_shadow_page(vcpu, iterator.sptep, sp); } } return emulate; } 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 void transparent_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t *gfnp, kvm_pfn_t *pfnp, int *levelp) { kvm_pfn_t pfn = *pfnp; gfn_t gfn = *gfnp; int level = *levelp; /* * Check if it's a transparent hugepage. If this would be an * hugetlbfs page, level wouldn't be set to * PT_PAGE_TABLE_LEVEL and there would be no adjustment done * here. */ if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn) && level == PT_PAGE_TABLE_LEVEL && PageTransCompoundMap(pfn_to_page(pfn)) && !mmu_gfn_lpage_is_disallowed(vcpu, gfn, PT_DIRECTORY_LEVEL)) { unsigned long mask; /* * mmu_notifier_retry was successful and we hold the * mmu_lock here, so the pmd can't become splitting * from under us, and in turn * __split_huge_page_refcount() can't run from under * us and we can safely transfer the refcount from * PG_tail to PG_head as we switch the pfn to tail to * head. */ *levelp = level = PT_DIRECTORY_LEVEL; mask = KVM_PAGES_PER_HPAGE(level) - 1; VM_BUG_ON((gfn & mask) != (pfn & mask)); if (pfn & mask) { gfn &= ~mask; *gfnp = gfn; kvm_release_pfn_clean(pfn); pfn &= ~mask; kvm_get_pfn(pfn); *pfnp = pfn; } } } static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, kvm_pfn_t pfn, unsigned 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); 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; } /* * Return value: * - true: let the vcpu to access on the same address again. * - false: let the real page fault path to fix it. */ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level, u32 error_code) { struct kvm_shadow_walk_iterator iterator; struct kvm_mmu_page *sp; bool fault_handled = false; u64 spte = 0ull; uint retry_count = 0; if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) return false; if (!page_fault_can_be_fast(error_code)) return false; walk_shadow_page_lockless_begin(vcpu); do { u64 new_spte; for_each_shadow_entry_lockless(vcpu, gva, iterator, spte) if (!is_shadow_present_pte(spte) || iterator.level < level) break; sp = page_header(__pa(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)) { fault_handled = true; 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 > PT_PAGE_TABLE_LEVEL) 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/virtual/kvm/locking.txt to get more detail. */ fault_handled = fast_pf_fix_direct_spte(vcpu, sp, iterator.sptep, spte, new_spte); if (fault_handled) 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, gva, error_code, iterator.sptep, spte, fault_handled); walk_shadow_page_lockless_end(vcpu); return fault_handled; } static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, gva_t gva, kvm_pfn_t *pfn, bool write, bool *writable); static int make_mmu_pages_available(struct kvm_vcpu *vcpu); static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code, gfn_t gfn, bool prefault) { int r; int level; bool force_pt_level = false; kvm_pfn_t pfn; unsigned long mmu_seq; bool map_writable, write = error_code & PFERR_WRITE_MASK; level = mapping_level(vcpu, gfn, &force_pt_level); if (likely(!force_pt_level)) { /* * This path builds a PAE pagetable - so we can map * 2mb pages at maximum. Therefore check if the level * is larger than that. */ if (level > PT_DIRECTORY_LEVEL) level = PT_DIRECTORY_LEVEL; gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1); } if (fast_page_fault(vcpu, v, level, error_code)) return RET_PF_RETRY; mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); if (try_async_pf(vcpu, prefault, gfn, v, &pfn, write, &map_writable)) return RET_PF_RETRY; if (handle_abnormal_pfn(vcpu, v, gfn, pfn, ACC_ALL, &r)) return r; spin_lock(&vcpu->kvm->mmu_lock); if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) goto out_unlock; if (make_mmu_pages_available(vcpu) < 0) goto out_unlock; if (likely(!force_pt_level)) transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level); r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault); spin_unlock(&vcpu->kvm->mmu_lock); return r; out_unlock: spin_unlock(&vcpu->kvm->mmu_lock); kvm_release_pfn_clean(pfn); return RET_PF_RETRY; } 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 = page_header(*root_hpa & PT64_BASE_ADDR_MASK); --sp->root_count; 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) { 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; } spin_lock(&vcpu->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(vcpu->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(vcpu->kvm, &mmu->root_hpa, &invalid_list); } else { for (i = 0; i < 4; ++i) if (mmu->pae_root[i] != 0) mmu_free_root_page(vcpu->kvm, &mmu->pae_root[i], &invalid_list); mmu->root_hpa = INVALID_PAGE; } } kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list); spin_unlock(&vcpu->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_is_visible_gfn(vcpu->kvm, root_gfn)) { kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); ret = 1; } return ret; } static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu_page *sp; unsigned i; if (vcpu->arch.mmu->shadow_root_level >= PT64_ROOT_4LEVEL) { spin_lock(&vcpu->kvm->mmu_lock); if(make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, 0, 0, vcpu->arch.mmu->shadow_root_level, 1, ACC_ALL); ++sp->root_count; spin_unlock(&vcpu->kvm->mmu_lock); vcpu->arch.mmu->root_hpa = __pa(sp->spt); } else if (vcpu->arch.mmu->shadow_root_level == PT32E_ROOT_LEVEL) { for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu->pae_root[i]; MMU_WARN_ON(VALID_PAGE(root)); spin_lock(&vcpu->kvm->mmu_lock); if (make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT), i << 30, PT32_ROOT_LEVEL, 1, ACC_ALL); root = __pa(sp->spt); ++sp->root_count; spin_unlock(&vcpu->kvm->mmu_lock); vcpu->arch.mmu->pae_root[i] = root | PT_PRESENT_MASK; } vcpu->arch.mmu->root_hpa = __pa(vcpu->arch.mmu->pae_root); } else BUG(); return 0; } static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu_page *sp; u64 pdptr, pm_mask; gfn_t root_gfn; int i; root_gfn = vcpu->arch.mmu->get_cr3(vcpu) >> PAGE_SHIFT; if (mmu_check_root(vcpu, root_gfn)) return 1; /* * Do we shadow a long mode page table? If so we need to * write-protect the guests page table root. */ if (vcpu->arch.mmu->root_level >= PT64_ROOT_4LEVEL) { hpa_t root = vcpu->arch.mmu->root_hpa; MMU_WARN_ON(VALID_PAGE(root)); spin_lock(&vcpu->kvm->mmu_lock); if (make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, root_gfn, 0, vcpu->arch.mmu->shadow_root_level, 0, ACC_ALL); root = __pa(sp->spt); ++sp->root_count; spin_unlock(&vcpu->kvm->mmu_lock); vcpu->arch.mmu->root_hpa = root; return 0; } /* * 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; if (vcpu->arch.mmu->shadow_root_level == PT64_ROOT_4LEVEL) pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu->pae_root[i]; MMU_WARN_ON(VALID_PAGE(root)); if (vcpu->arch.mmu->root_level == PT32E_ROOT_LEVEL) { pdptr = vcpu->arch.mmu->get_pdptr(vcpu, i); if (!(pdptr & PT_PRESENT_MASK)) { vcpu->arch.mmu->pae_root[i] = 0; continue; } root_gfn = pdptr >> PAGE_SHIFT; if (mmu_check_root(vcpu, root_gfn)) return 1; } spin_lock(&vcpu->kvm->mmu_lock); if (make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL, 0, ACC_ALL); root = __pa(sp->spt); ++sp->root_count; spin_unlock(&vcpu->kvm->mmu_lock); vcpu->arch.mmu->pae_root[i] = root | pm_mask; } vcpu->arch.mmu->root_hpa = __pa(vcpu->arch.mmu->pae_root); /* * If we shadow a 32 bit page table with a long mode page * table we enter this path. */ if (vcpu->arch.mmu->shadow_root_level == PT64_ROOT_4LEVEL) { if (vcpu->arch.mmu->lm_root == NULL) { /* * The additional page necessary for this is only * allocated on demand. */ u64 *lm_root; lm_root = (void*)get_zeroed_page(GFP_KERNEL); if (lm_root == NULL) return 1; lm_root[0] = __pa(vcpu->arch.mmu->pae_root) | pm_mask; vcpu->arch.mmu->lm_root = lm_root; } vcpu->arch.mmu->root_hpa = __pa(vcpu->arch.mmu->lm_root); } return 0; } static int mmu_alloc_roots(struct kvm_vcpu *vcpu) { if (vcpu->arch.mmu->direct_map) return mmu_alloc_direct_roots(vcpu); else return mmu_alloc_shadow_roots(vcpu); } 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 = page_header(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; spin_lock(&vcpu->kvm->mmu_lock); kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC); mmu_sync_children(vcpu, sp); kvm_mmu_audit(vcpu, AUDIT_POST_SYNC); spin_unlock(&vcpu->kvm->mmu_lock); return; } spin_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 (root && VALID_PAGE(root)) { root &= PT64_BASE_ADDR_MASK; sp = page_header(root); mmu_sync_children(vcpu, sp); } } kvm_mmu_audit(vcpu, AUDIT_POST_SYNC); spin_unlock(&vcpu->kvm->mmu_lock); } EXPORT_SYMBOL_GPL(kvm_mmu_sync_roots); static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_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, gva_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, low6 = pte & 0x3f; return (pte & rsvd_check->rsvd_bits_mask[bit7][level-1]) | ((rsvd_check->bad_mt_xwr & (1ull << low6)) != 0); } static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level) { return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level); } static bool is_shadow_zero_bits_set(struct kvm_mmu *mmu, u64 spte, int level) { return __is_rsvd_bits_set(&mmu->shadow_zero_check, spte, level); } 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 true if reserved bit is detected on spte. */ static bool walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) { struct kvm_shadow_walk_iterator iterator; u64 sptes[PT64_ROOT_MAX_LEVEL], spte = 0ull; int root, leaf; bool reserved = false; if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) goto exit; walk_shadow_page_lockless_begin(vcpu); for (shadow_walk_init(&iterator, vcpu, addr), leaf = root = iterator.level; shadow_walk_okay(&iterator); __shadow_walk_next(&iterator, spte)) { spte = mmu_spte_get_lockless(iterator.sptep); sptes[leaf - 1] = spte; leaf--; if (!is_shadow_present_pte(spte)) break; reserved |= is_shadow_zero_bits_set(vcpu->arch.mmu, spte, iterator.level); } walk_shadow_page_lockless_end(vcpu); if (reserved) { pr_err("%s: detect reserved bits on spte, addr 0x%llx, dump hierarchy:\n", __func__, addr); while (root > leaf) { pr_err("------ spte 0x%llx level %d.\n", sptes[root - 1], root); root--; } } exit: *sptep = spte; 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 = walk_shadow_page_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 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; if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) return; 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 int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code, bool prefault) { gfn_t gfn = gva >> PAGE_SHIFT; int r; pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code); if (page_fault_handle_page_track(vcpu, error_code, gfn)) return RET_PF_EMULATE; r = mmu_topup_memory_caches(vcpu); if (r) return r; MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)); return nonpaging_map(vcpu, gva & PAGE_MASK, error_code, gfn, prefault); } static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, 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_cr3(vcpu); return kvm_setup_async_pf(vcpu, gva, kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); } bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu) { if (unlikely(!lapic_in_kernel(vcpu) || kvm_event_needs_reinjection(vcpu) || vcpu->arch.exception.pending)) return false; if (!vcpu->arch.apf.delivery_as_pf_vmexit && is_guest_mode(vcpu)) return false; return kvm_x86_ops->interrupt_allowed(vcpu); } static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, gva_t gva, kvm_pfn_t *pfn, bool write, bool *writable) { struct kvm_memory_slot *slot; bool async; /* * Don't expose private memslots to L2. */ if (is_guest_mode(vcpu) && !kvm_is_visible_gfn(vcpu->kvm, gfn)) { *pfn = KVM_PFN_NOSLOT; return false; } slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); async = false; *pfn = __gfn_to_pfn_memslot(slot, gfn, false, &async, write, writable); if (!async) return false; /* *pfn has correct page already */ if (!prefault && kvm_can_do_async_pf(vcpu)) { trace_kvm_try_async_get_page(gva, gfn); if (kvm_find_async_pf_gfn(vcpu, gfn)) { trace_kvm_async_pf_doublefault(gva, gfn); kvm_make_request(KVM_REQ_APF_HALT, vcpu); return true; } else if (kvm_arch_setup_async_pf(vcpu, gva, gfn)) return true; } *pfn = __gfn_to_pfn_memslot(slot, gfn, false, NULL, write, writable); return false; } int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, u64 fault_address, char *insn, int insn_len) { int r = 1; vcpu->arch.l1tf_flush_l1d = true; switch (vcpu->arch.apf.host_apf_reason) { default: 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); break; case KVM_PV_REASON_PAGE_NOT_PRESENT: vcpu->arch.apf.host_apf_reason = 0; local_irq_disable(); kvm_async_pf_task_wait(fault_address, 0); local_irq_enable(); break; case KVM_PV_REASON_PAGE_READY: vcpu->arch.apf.host_apf_reason = 0; local_irq_disable(); kvm_async_pf_task_wake(fault_address); local_irq_enable(); break; } return r; } EXPORT_SYMBOL_GPL(kvm_handle_page_fault); static bool check_hugepage_cache_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, int level) { int page_num = KVM_PAGES_PER_HPAGE(level); gfn &= ~(page_num - 1); return kvm_mtrr_check_gfn_range_consistency(vcpu, gfn, page_num); } static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code, bool prefault) { kvm_pfn_t pfn; int r; int level; bool force_pt_level; gfn_t gfn = gpa >> PAGE_SHIFT; unsigned long mmu_seq; int write = error_code & PFERR_WRITE_MASK; bool map_writable; MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)); if (page_fault_handle_page_track(vcpu, error_code, gfn)) return RET_PF_EMULATE; r = mmu_topup_memory_caches(vcpu); if (r) return r; force_pt_level = !check_hugepage_cache_consistency(vcpu, gfn, PT_DIRECTORY_LEVEL); level = mapping_level(vcpu, gfn, &force_pt_level); if (likely(!force_pt_level)) { if (level > PT_DIRECTORY_LEVEL && !check_hugepage_cache_consistency(vcpu, gfn, level)) level = PT_DIRECTORY_LEVEL; gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1); } if (fast_page_fault(vcpu, gpa, level, error_code)) return RET_PF_RETRY; mmu_seq = vcpu->kvm->mmu_notifier_seq; smp_rmb(); if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, write, &map_writable)) return RET_PF_RETRY; if (handle_abnormal_pfn(vcpu, 0, gfn, pfn, ACC_ALL, &r)) return r; spin_lock(&vcpu->kvm->mmu_lock); if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) goto out_unlock; if (make_mmu_pages_available(vcpu) < 0) goto out_unlock; if (likely(!force_pt_level)) transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level); r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault); spin_unlock(&vcpu->kvm->mmu_lock); return r; out_unlock: spin_unlock(&vcpu->kvm->mmu_lock); kvm_release_pfn_clean(pfn); return RET_PF_RETRY; } 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 = nonpaging_invlpg; context->update_pte = nonpaging_update_pte; context->root_level = 0; context->shadow_root_level = PT32E_ROOT_LEVEL; context->direct_map = true; context->nx = false; } /* * Find out if a previously cached root matching the new CR3/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_cr3, union kvm_mmu_page_role new_role) { uint i; struct kvm_mmu_root_info root; struct kvm_mmu *mmu = vcpu->arch.mmu; root.cr3 = mmu->get_cr3(vcpu); root.hpa = mmu->root_hpa; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { swap(root, mmu->prev_roots[i]); if (new_cr3 == root.cr3 && VALID_PAGE(root.hpa) && page_header(root.hpa) != NULL && new_role.word == page_header(root.hpa)->role.word) break; } mmu->root_hpa = root.hpa; return i < KVM_MMU_NUM_PREV_ROOTS; } static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3, union kvm_mmu_page_role new_role, bool skip_tlb_flush) { 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) { if (mmu_check_root(vcpu, new_cr3 >> PAGE_SHIFT)) return false; if (cached_root_available(vcpu, new_cr3, new_role)) { /* * It is possible that the cached previous root page is * obsolete because of a change in the MMU * generation number. However, that is accompanied by * KVM_REQ_MMU_RELOAD, which will free the root that we * have set here and allocate a new one. */ kvm_make_request(KVM_REQ_LOAD_CR3, vcpu); if (!skip_tlb_flush) { kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); kvm_x86_ops->tlb_flush(vcpu, true); } /* * 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); __clear_sp_write_flooding_count( page_header(mmu->root_hpa)); return true; } } return false; } static void __kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, union kvm_mmu_page_role new_role, bool skip_tlb_flush) { if (!fast_cr3_switch(vcpu, new_cr3, new_role, skip_tlb_flush)) kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT); } void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush) { __kvm_mmu_new_cr3(vcpu, new_cr3, kvm_mmu_calc_root_page_role(vcpu), skip_tlb_flush); } EXPORT_SYMBOL_GPL(kvm_mmu_new_cr3); static unsigned long get_cr3(struct kvm_vcpu *vcpu) { return kvm_read_cr3(vcpu); } static void inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) { vcpu->arch.mmu->inject_page_fault(vcpu, fault); } static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, unsigned 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; /* * PT_PAGE_TABLE_LEVEL always terminates. The RHS has bit 7 set * iff level <= PT_PAGE_TABLE_LEVEL, which for our purpose means * level == PT_PAGE_TABLE_LEVEL; set PT_PAGE_SIZE_MASK in gpte then. */ gpte |= level - PT_PAGE_TABLE_LEVEL - 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, int maxphyaddr, int level, bool nx, bool gbpages, bool pse, bool amd) { u64 exb_bit_rsvd = 0; u64 gbpages_bit_rsvd = 0; u64 nonleaf_bit8_rsvd = 0; rsvd_check->bad_mt_xwr = 0; if (!nx) exb_bit_rsvd = rsvd_bits(63, 63); if (!gbpages) gbpages_bit_rsvd = rsvd_bits(7, 7); /* * 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(maxphyaddr, 63) | rsvd_bits(5, 8) | rsvd_bits(1, 2); /* PDPTE */ rsvd_check->rsvd_bits_mask[0][1] = exb_bit_rsvd | rsvd_bits(maxphyaddr, 62); /* PDE */ rsvd_check->rsvd_bits_mask[0][0] = exb_bit_rsvd | rsvd_bits(maxphyaddr, 62); /* PTE */ rsvd_check->rsvd_bits_mask[1][1] = exb_bit_rsvd | rsvd_bits(maxphyaddr, 62) | 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] = exb_bit_rsvd | nonleaf_bit8_rsvd | rsvd_bits(7, 7) | rsvd_bits(maxphyaddr, 51); rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4]; case PT64_ROOT_4LEVEL: rsvd_check->rsvd_bits_mask[0][3] = exb_bit_rsvd | nonleaf_bit8_rsvd | rsvd_bits(7, 7) | rsvd_bits(maxphyaddr, 51); rsvd_check->rsvd_bits_mask[0][2] = exb_bit_rsvd | nonleaf_bit8_rsvd | gbpages_bit_rsvd | rsvd_bits(maxphyaddr, 51); rsvd_check->rsvd_bits_mask[0][1] = exb_bit_rsvd | rsvd_bits(maxphyaddr, 51); rsvd_check->rsvd_bits_mask[0][0] = exb_bit_rsvd | rsvd_bits(maxphyaddr, 51); rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3]; rsvd_check->rsvd_bits_mask[1][2] = exb_bit_rsvd | gbpages_bit_rsvd | rsvd_bits(maxphyaddr, 51) | rsvd_bits(13, 29); rsvd_check->rsvd_bits_mask[1][1] = exb_bit_rsvd | rsvd_bits(maxphyaddr, 51) | 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, cpuid_maxphyaddr(vcpu), context->root_level, context->nx, guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES), is_pse(vcpu), guest_cpuid_is_amd(vcpu)); } static void __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, int maxphyaddr, bool execonly) { u64 bad_mt_xwr; rsvd_check->rsvd_bits_mask[0][4] = rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7); rsvd_check->rsvd_bits_mask[0][3] = rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 7); rsvd_check->rsvd_bits_mask[0][2] = rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6); rsvd_check->rsvd_bits_mask[0][1] = rsvd_bits(maxphyaddr, 51) | rsvd_bits(3, 6); rsvd_check->rsvd_bits_mask[0][0] = rsvd_bits(maxphyaddr, 51); /* 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] = rsvd_bits(maxphyaddr, 51) | rsvd_bits(12, 29); rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(maxphyaddr, 51) | 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, cpuid_maxphyaddr(vcpu), execonly); } /* * 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, boot_cpu_data.x86_phys_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, boot_cpu_data.x86_phys_bits, context->shadow_root_level, false, boot_cpu_has(X86_FEATURE_GBPAGES), true, true); else __reset_rsvds_bits_mask_ept(shadow_zero_check, boot_cpu_data.x86_phys_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, boot_cpu_data.x86_phys_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) ? ~w : 0; /* Faults from user mode accesses to supervisor pages */ u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0; /* Faults from fetches of non-executable pages*/ u8 ff = (pfec & PFERR_FETCH_MASK) ? ~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->update_pte = paging64_update_pte; 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->update_pte = paging32_update_pte; 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_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.cr4_la57 = !!kvm_read_cr4_bits(vcpu, X86_CR4_LA57); 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.cr4_pae = !!is_pae(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 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_x86_ops->get_tdp_level(vcpu); role.base.direct = true; return role; } static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = vcpu->arch.mmu; union kvm_mmu_role new_role = kvm_calc_tdp_mmu_root_page_role(vcpu, false); new_role.base.word &= mmu_base_role_mask.word; if (new_role.as_u64 == context->mmu_role.as_u64) return; context->mmu_role.as_u64 = new_role.as_u64; context->page_fault = tdp_page_fault; context->sync_page = nonpaging_sync_page; context->invlpg = nonpaging_invlpg; context->update_pte = nonpaging_update_pte; context->shadow_root_level = kvm_x86_ops->get_tdp_level(vcpu); context->direct_map = true; context->set_cr3 = kvm_x86_ops->set_tdp_cr3; context->get_cr3 = 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_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.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.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; } void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu) { struct kvm_mmu *context = vcpu->arch.mmu; union kvm_mmu_role new_role = kvm_calc_shadow_mmu_root_page_role(vcpu, false); new_role.base.word &= mmu_base_role_mask.word; if (new_role.as_u64 == context->mmu_role.as_u64) return; if (!is_paging(vcpu)) nonpaging_init_context(vcpu, context); else if (is_long_mode(vcpu)) paging64_init_context(vcpu, context); else if (is_pae(vcpu)) 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); } EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu); static union kvm_mmu_role kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty, bool execonly) { union kvm_mmu_role role; /* Base role is inherited from root_mmu */ role.base.word = vcpu->arch.root_mmu.mmu_role.base.word; role.ext = kvm_calc_mmu_role_ext(vcpu); role.base.level = PT64_ROOT_4LEVEL; role.base.direct = false; role.base.ad_disabled = !accessed_dirty; role.base.guest_mode = true; role.base.access = ACC_ALL; 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.mmu; union kvm_mmu_role new_role = kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, execonly); __kvm_mmu_new_cr3(vcpu, new_eptp, new_role.base, false); new_role.base.word &= mmu_base_role_mask.word; if (new_role.as_u64 == context->mmu_role.as_u64) return; context->shadow_root_level = PT64_ROOT_4LEVEL; 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->update_pte = ept_update_pte; context->root_level = PT64_ROOT_4LEVEL; 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.mmu; kvm_init_shadow_mmu(vcpu); context->set_cr3 = kvm_x86_ops->set_cr3; context->get_cr3 = get_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; } static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu) { union kvm_mmu_role new_role = kvm_calc_mmu_role_common(vcpu, false); struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; new_role.base.word &= mmu_base_role_mask.word; 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_cr3 = get_cr3; g_context->get_pdptr = kvm_pdptr_read; g_context->inject_page_fault = kvm_inject_page_fault; /* * 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); if (r) goto out; r = mmu_alloc_roots(vcpu); kvm_mmu_sync_roots(vcpu); if (r) goto out; kvm_mmu_load_cr3(vcpu); kvm_x86_ops->tlb_flush(vcpu, true); out: return r; } EXPORT_SYMBOL_GPL(kvm_mmu_load); 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)); } EXPORT_SYMBOL_GPL(kvm_mmu_unload); static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *spte, const void *new) { if (sp->role.level != PT_PAGE_TABLE_LEVEL) { ++vcpu->kvm->stat.mmu_pde_zapped; return; } ++vcpu->kvm->stat.mmu_pte_updated; vcpu->arch.mmu->update_pte(vcpu, sp, spte, new); } 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 == PT_PAGE_TABLE_LEVEL) 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.cr4_pae ? 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.cr4_pae) { 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 skiped if it does not have * enough objects in the cache. */ mmu_topup_memory_caches(vcpu); spin_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--) { u32 base_role = vcpu->arch.mmu->mmu_role.base.word; entry = *spte; mmu_page_zap_pte(vcpu->kvm, sp, spte); if (gentry && !((sp->role.word ^ base_role) & mmu_base_role_mask.word) && rmap_can_add(vcpu)) mmu_pte_write_new_pte(vcpu, sp, spte, &gentry); 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); spin_unlock(&vcpu->kvm->mmu_lock); } 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; } EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt); static int make_mmu_pages_available(struct kvm_vcpu *vcpu) { LIST_HEAD(invalid_list); if (likely(kvm_mmu_available_pages(vcpu->kvm) >= KVM_MIN_FREE_MMU_PAGES)) return 0; while (kvm_mmu_available_pages(vcpu->kvm) < KVM_REFILL_PAGES) { if (!prepare_zap_oldest_mmu_page(vcpu->kvm, &invalid_list)) break; ++vcpu->kvm->stat.mmu_recycled; } kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list); if (!kvm_mmu_available_pages(vcpu->kvm)) return -ENOSPC; return 0; } int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code, void *insn, int insn_len) { int r, emulation_type = 0; enum emulation_result er; bool direct = vcpu->arch.mmu->direct_map; /* With shadow page tables, fault_address contains a GVA or nGPA. */ if (vcpu->arch.mmu->direct_map) { vcpu->arch.gpa_available = true; vcpu->arch.gpa_val = cr2; } r = RET_PF_INVALID; if (unlikely(error_code & PFERR_RSVD_MASK)) { r = handle_mmio_page_fault(vcpu, cr2, direct); if (r == RET_PF_EMULATE) goto emulate; } if (r == RET_PF_INVALID) { r = vcpu->arch.mmu->page_fault(vcpu, cr2, lower_32_bits(error_code), false); WARN_ON(r == RET_PF_INVALID); } if (r == RET_PF_RETRY) return 1; if (r < 0) return r; /* * 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)); 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, direct) && !is_guest_mode(vcpu)) emulation_type = EMULTYPE_ALLOW_RETRY; emulate: /* * On AMD platforms, under certain conditions insn_len may be zero on #NPF. * This can happen if a guest gets a page-fault on data access but the HW * table walker is not able to read the instruction page (e.g instruction * page is not present in memory). In those cases we simply restart the * guest. */ if (unlikely(insn && !insn_len)) return 1; er = x86_emulate_instruction(vcpu, cr2, emulation_type, insn, insn_len); switch (er) { case EMULATE_DONE: return 1; case EMULATE_USER_EXIT: ++vcpu->stat.mmio_exits; /* fall through */ case EMULATE_FAIL: return 0; default: BUG(); } } EXPORT_SYMBOL_GPL(kvm_mmu_page_fault); void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva) { struct kvm_mmu *mmu = vcpu->arch.mmu; int i; /* INVLPG on a * non-canonical address is a NOP according to the SDM. */ if (is_noncanonical_address(gva, vcpu)) return; 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); kvm_x86_ops->tlb_flush_gva(vcpu, gva); ++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].cr3)) { mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); tlb_flush = true; } } if (tlb_flush) kvm_x86_ops->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. */ } EXPORT_SYMBOL_GPL(kvm_mmu_invpcid_gva); void kvm_enable_tdp(void) { tdp_enabled = true; } EXPORT_SYMBOL_GPL(kvm_enable_tdp); void kvm_disable_tdp(void) { tdp_enabled = false; } EXPORT_SYMBOL_GPL(kvm_disable_tdp); static void free_mmu_pages(struct kvm_vcpu *vcpu) { free_page((unsigned long)vcpu->arch.mmu->pae_root); free_page((unsigned long)vcpu->arch.mmu->lm_root); } static int alloc_mmu_pages(struct kvm_vcpu *vcpu) { struct page *page; int i; if (tdp_enabled) return 0; /* * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64. * Therefore we need to allocate shadow page tables in the first * 4GB of memory, which happens to fit the DMA32 zone. */ page = alloc_page(GFP_KERNEL | __GFP_DMA32); if (!page) return -ENOMEM; vcpu->arch.mmu->pae_root = page_address(page); for (i = 0; i < 4; ++i) vcpu->arch.mmu->pae_root[i] = INVALID_PAGE; return 0; } int kvm_mmu_create(struct kvm_vcpu *vcpu) { uint i; vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; vcpu->arch.root_mmu.root_hpa = INVALID_PAGE; vcpu->arch.root_mmu.translate_gpa = translate_gpa; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) vcpu->arch.root_mmu.prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; vcpu->arch.guest_mmu.root_hpa = INVALID_PAGE; vcpu->arch.guest_mmu.translate_gpa = translate_gpa; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) vcpu->arch.guest_mmu.prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; vcpu->arch.nested_mmu.translate_gpa = translate_nested_gpa; return alloc_mmu_pages(vcpu); } 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_invalidate_zap_all_pages(kvm); } void kvm_mmu_init_vm(struct kvm *kvm) { struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; 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); } /* 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); /* 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 lock_flush_tlb) { struct slot_rmap_walk_iterator iterator; bool flush = false; for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn, end_gfn, &iterator) { if (iterator.rmap) flush |= fn(kvm, iterator.rmap); if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { if (flush && lock_flush_tlb) { kvm_flush_remote_tlbs(kvm); flush = false; } cond_resched_lock(&kvm->mmu_lock); } } if (flush && lock_flush_tlb) { kvm_flush_remote_tlbs(kvm); flush = false; } 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 lock_flush_tlb) { return slot_handle_level_range(kvm, memslot, fn, start_level, end_level, memslot->base_gfn, memslot->base_gfn + memslot->npages - 1, lock_flush_tlb); } static __always_inline bool slot_handle_all_level(struct kvm *kvm, struct kvm_memory_slot *memslot, slot_level_handler fn, bool lock_flush_tlb) { return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL, lock_flush_tlb); } static __always_inline bool slot_handle_large_level(struct kvm *kvm, struct kvm_memory_slot *memslot, slot_level_handler fn, bool lock_flush_tlb) { return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL + 1, PT_MAX_HUGEPAGE_LEVEL, lock_flush_tlb); } static __always_inline bool slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot, slot_level_handler fn, bool lock_flush_tlb) { return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL, PT_PAGE_TABLE_LEVEL, lock_flush_tlb); } 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; spin_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; slot_handle_level_range(kvm, memslot, kvm_zap_rmapp, PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL, start, end - 1, true); } } spin_unlock(&kvm->mmu_lock); } static bool slot_rmap_write_protect(struct kvm *kvm, struct kvm_rmap_head *rmap_head) { return __rmap_write_protect(kvm, rmap_head, false); } void kvm_mmu_slot_remove_write_access(struct kvm *kvm, struct kvm_memory_slot *memslot) { bool flush; spin_lock(&kvm->mmu_lock); flush = slot_handle_all_level(kvm, memslot, slot_rmap_write_protect, false); spin_unlock(&kvm->mmu_lock); /* * kvm_mmu_slot_remove_write_access() and kvm_vm_ioctl_get_dirty_log() * which do tlb flush out of mmu-lock should be serialized by * kvm->slots_lock otherwise tlb flush would be missed. */ lockdep_assert_held(&kvm->slots_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 * haved checked SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE * instead of PT_WRITABLE_MASK, that means it does not depend * on PT_WRITABLE_MASK anymore. */ if (flush) kvm_flush_remote_tlbs(kvm); } static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, struct kvm_rmap_head *rmap_head) { 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 = page_header(__pa(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) && PageTransCompoundMap(pfn_to_page(pfn))) { pte_list_remove(rmap_head, sptep); 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. */ spin_lock(&kvm->mmu_lock); slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot, kvm_mmu_zap_collapsible_spte, true); spin_unlock(&kvm->mmu_lock); } void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, struct kvm_memory_slot *memslot) { bool flush; spin_lock(&kvm->mmu_lock); flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, false); spin_unlock(&kvm->mmu_lock); lockdep_assert_held(&kvm->slots_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_flush_remote_tlbs(kvm); } EXPORT_SYMBOL_GPL(kvm_mmu_slot_leaf_clear_dirty); void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm, struct kvm_memory_slot *memslot) { bool flush; spin_lock(&kvm->mmu_lock); flush = slot_handle_large_level(kvm, memslot, slot_rmap_write_protect, false); spin_unlock(&kvm->mmu_lock); /* see kvm_mmu_slot_remove_write_access */ lockdep_assert_held(&kvm->slots_lock); if (flush) kvm_flush_remote_tlbs(kvm); } EXPORT_SYMBOL_GPL(kvm_mmu_slot_largepage_remove_write_access); void kvm_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *memslot) { bool flush; spin_lock(&kvm->mmu_lock); flush = slot_handle_all_level(kvm, memslot, __rmap_set_dirty, false); spin_unlock(&kvm->mmu_lock); lockdep_assert_held(&kvm->slots_lock); /* see kvm_mmu_slot_leaf_clear_dirty */ if (flush) kvm_flush_remote_tlbs(kvm); } EXPORT_SYMBOL_GPL(kvm_mmu_slot_set_dirty); #define BATCH_ZAP_PAGES 10 static void kvm_zap_obsolete_pages(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; int batch = 0; restart: list_for_each_entry_safe_reverse(sp, node, &kvm->arch.active_mmu_pages, link) { int ret; /* * No obsolete page exists before new created page since * active_mmu_pages is the FIFO list. */ if (!is_obsolete_sp(kvm, sp)) break; /* * Since we are reversely walking the list and the invalid * list will be moved to the head, skip the invalid page * can help us to avoid the infinity list walking. */ if (sp->role.invalid) continue; /* * Need not flush tlb since we only zap the sp with invalid * generation number. */ if (batch >= BATCH_ZAP_PAGES && cond_resched_lock(&kvm->mmu_lock)) { batch = 0; goto restart; } ret = kvm_mmu_prepare_zap_page(kvm, sp, &kvm->arch.zapped_obsolete_pages); batch += ret; if (ret) goto restart; } /* * Should flush tlb before free page tables since lockless-walking * may use 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. */ void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm) { spin_lock(&kvm->mmu_lock); trace_kvm_mmu_invalidate_zap_all_pages(kvm); kvm->arch.mmu_valid_gen++; /* * 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 should 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); spin_unlock(&kvm->mmu_lock); } static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) { return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); } void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, struct kvm_memslots *slots) { /* * The very rare case: if the generation-number is round, * zap all shadow pages. */ if (unlikely((slots->generation & MMIO_GEN_MASK) == 0)) { kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n"); kvm_mmu_invalidate_zap_all_pages(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; spin_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); spin_lock(&kvm->mmu_lock); if (kvm_has_zapped_obsolete_pages(kvm)) { kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); goto unlock; } if (prepare_zap_oldest_mmu_page(kvm, &invalid_list)) freed++; kvm_mmu_commit_zap_page(kvm, &invalid_list); unlock: spin_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; } spin_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); } int kvm_mmu_module_init(void) { int ret = -ENOMEM; /* * 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 int kvm_mmu_calculate_mmu_pages(struct kvm *kvm) { unsigned int nr_mmu_pages; unsigned int 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, (unsigned int) 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); 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(); }
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