cregit-Linux how code gets into the kernel

Release 4.14 arch/powerpc/kvm/book3s_64_mmu_hv.c

Directory: arch/powerpc/kvm
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright 2010 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/vmalloc.h>
#include <linux/srcu.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/debugfs.h>

#include <asm/tlbflush.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/book3s/64/mmu-hash.h>
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>
#include <asm/pte-walk.h>

#include "trace_hv.h"

//#define DEBUG_RESIZE_HPT      1

#ifdef DEBUG_RESIZE_HPT

#define resize_hpt_debug(resize, ...)				\
	do {                                                    \
                printk(KERN_DEBUG "RESIZE HPT %p: ", resize);   \
                printk(__VA_ARGS__);                            \
        } while (0)
#else

#define resize_hpt_debug(resize, ...)				\
	do { } while (0)
#endif

static long kvmppc_virtmode_do_h_enter(struct kvm *kvm, unsigned long flags,
				long pte_index, unsigned long pteh,
				unsigned long ptel, unsigned long *pte_idx_ret);


struct kvm_resize_hpt {
	/* These fields read-only after init */
	
struct kvm *kvm;
	
struct work_struct work;
	
u32 order;

	/* These fields protected by kvm->lock */
	
int error;
	
bool prepare_done;

	/* Private to the work thread, until prepare_done is true,
         * then protected by kvm->resize_hpt_sem */
	
struct kvm_hpt_info hpt;
};

static void kvmppc_rmap_reset(struct kvm *kvm);




int kvmppc_allocate_hpt(struct kvm_hpt_info *info, u32 order)
{
	unsigned long hpt = 0;
	int cma = 0;
	struct page *page = NULL;
	struct revmap_entry *rev;
	unsigned long npte;

	if ((order < PPC_MIN_HPT_ORDER) || (order > PPC_MAX_HPT_ORDER))
		return -EINVAL;

	page = kvm_alloc_hpt_cma(1ul << (order - PAGE_SHIFT));
	if (page) {
		hpt = (unsigned long)pfn_to_kaddr(page_to_pfn(page));
		memset((void *)hpt, 0, (1ul << order));
		cma = 1;
	}

	if (!hpt)
		hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_RETRY_MAYFAIL
				       |__GFP_NOWARN, order - PAGE_SHIFT);

	if (!hpt)
		return -ENOMEM;

	/* HPTEs are 2**4 bytes long */
	npte = 1ul << (order - 4);

	/* Allocate reverse map array */
	rev = vmalloc(sizeof(struct revmap_entry) * npte);
	if (!rev) {
		pr_err("kvmppc_allocate_hpt: Couldn't alloc reverse map array\n");
		if (cma)
			kvm_free_hpt_cma(page, 1 << (order - PAGE_SHIFT));
		else
			free_pages(hpt, order - PAGE_SHIFT);
		return -ENOMEM;
	}

	info->order = order;
	info->virt = hpt;
	info->cma = cma;
	info->rev = rev;

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
David Gibson10042.02%323.08%


Paul Mackerras7531.51%323.08%


Aneesh Kumar K.V2711.34%215.38%


JoonSoo Kim166.72%17.69%


Alexander Graf166.72%17.69%


Laurent Dufour20.84%17.69%


Yongji Xie10.42%17.69%


Michal Hocko10.42%17.69%


Total238100.00%13100.00%






void kvmppc_set_hpt(struct kvm *kvm, struct kvm_hpt_info *info)
{
	atomic64_set(&kvm->arch.mmio_update, 0);
	kvm->arch.hpt = *info;
	kvm->arch.sdr1 = __pa(info->virt) | (info->order - 18);

	pr_debug("KVM guest htab at %lx (order %ld), LPID %x\n",
		 info->virt, (long)info->order, kvm->arch.lpid);
}


Contributors
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David Gibson4253.16%233.33%


Paul Mackerras3645.57%350.00%


Thomas Huth11.27%116.67%


Total79100.00%6100.00%






long kvmppc_alloc_reset_hpt(struct kvm *kvm, int order)
{
	long err = -EBUSY;
	struct kvm_hpt_info info;

	if (kvm_is_radix(kvm))
		return -EINVAL;

	mutex_lock(&kvm->lock);
	if (kvm->arch.hpte_setup_done) {
		kvm->arch.hpte_setup_done = 0;
		/* order hpte_setup_done vs. vcpus_running */
		smp_mb();
		if (atomic_read(&kvm->arch.vcpus_running)) {
			kvm->arch.hpte_setup_done = 1;
			goto out;
		}
	}
	if (kvm->arch.hpt.order == order) {
		/* We already have a suitable HPT */

		/* Set the entire HPT to 0, i.e. invalid HPTEs */
		memset((void *)kvm->arch.hpt.virt, 0, 1ul << order);
		/*
                 * Reset all the reverse-mapping chains for all memslots
                 */
		kvmppc_rmap_reset(kvm);
		/* Ensure that each vcpu will flush its TLB on next entry. */
		cpumask_setall(&kvm->arch.need_tlb_flush);
		err = 0;
		goto out;
	}

	if (kvm->arch.hpt.virt) {
		kvmppc_free_hpt(&kvm->arch.hpt);
		kvmppc_rmap_reset(kvm);
	}

	err = kvmppc_allocate_hpt(&info, order);
	if (err < 0)
		goto out;
	kvmppc_set_hpt(kvm, &info);

out:
	mutex_unlock(&kvm->lock);
	return err;
}


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Paul Mackerras15571.43%555.56%


David Gibson5826.73%333.33%


Aneesh Kumar K.V41.84%111.11%


Total217100.00%9100.00%






void kvmppc_free_hpt(struct kvm_hpt_info *info)
{
	vfree(info->rev);
	if (info->cma)
		kvm_free_hpt_cma(virt_to_page(info->virt),
				 1 << (info->order - PAGE_SHIFT));
	else if (info->virt)
		free_pages(info->virt, info->order - PAGE_SHIFT);
	info->virt = 0;
	info->order = 0;
}


Contributors
PersonTokensPropCommitsCommitProp
David Gibson2938.67%333.33%


Paul Mackerras2736.00%444.44%


Aneesh Kumar K.V1013.33%111.11%


Alexander Graf912.00%111.11%


Total75100.00%9100.00%



/* Bits in first HPTE dword for pagesize 4k, 64k or 16M */



static inline unsigned long hpte0_pgsize_encoding(unsigned long pgsize)
{
	return (pgsize > 0x1000) ? HPTE_V_LARGE : 0;
}


Contributors
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Paul Mackerras23100.00%1100.00%


Total23100.00%1100.00%



/* Bits in second HPTE dword for pagesize 4k, 64k or 16M */



static inline unsigned long hpte1_pgsize_encoding(unsigned long pgsize)
{
	return (pgsize == 0x10000) ? 0x1000 : 0;
}


Contributors
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Paul Mackerras23100.00%1100.00%


Total23100.00%1100.00%






void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot,
		     unsigned long porder)
{
	unsigned long i;
	unsigned long npages;
	unsigned long hp_v, hp_r;
	unsigned long addr, hash;
	unsigned long psize;
	unsigned long hp0, hp1;
	unsigned long idx_ret;
	long ret;
	struct kvm *kvm = vcpu->kvm;

	psize = 1ul << porder;
	npages = memslot->npages >> (porder - PAGE_SHIFT);

	/* VRMA can't be > 1TB */
	if (npages > 1ul << (40 - porder))
		npages = 1ul << (40 - porder);
	/* Can't use more than 1 HPTE per HPTEG */
	if (npages > kvmppc_hpt_mask(&kvm->arch.hpt) + 1)
		npages = kvmppc_hpt_mask(&kvm->arch.hpt) + 1;

	hp0 = HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)) |
		HPTE_V_BOLTED | hpte0_pgsize_encoding(psize);
	hp1 = hpte1_pgsize_encoding(psize) |
		HPTE_R_R | HPTE_R_C | HPTE_R_M | PP_RWXX;

	for (i = 0; i < npages; ++i) {
		addr = i << porder;
		/* can't use hpt_hash since va > 64 bits */
		hash = (i ^ (VRMA_VSID ^ (VRMA_VSID << 25)))
			& kvmppc_hpt_mask(&kvm->arch.hpt);
		/*
                 * We assume that the hash table is empty and no
                 * vcpus are using it at this stage.  Since we create
                 * at most one HPTE per HPTEG, we just assume entry 7
                 * is available and use it.
                 */
		hash = (hash << 3) + 7;
		hp_v = hp0 | ((addr >> 16) & ~0x7fUL);
		hp_r = hp1 | addr;
		ret = kvmppc_virtmode_do_h_enter(kvm, H_EXACT, hash, hp_v, hp_r,
						 &idx_ret);
		if (ret != H_SUCCESS) {
			pr_err("KVM: map_vrma at %lx failed, ret=%ld\n",
			       addr, ret);
			break;
		}
	}
}


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Paul Mackerras27494.81%777.78%


David Gibson155.19%222.22%


Total289100.00%9100.00%






int kvmppc_mmu_hv_init(void)
{
	unsigned long host_lpid, rsvd_lpid;

	if (!cpu_has_feature(CPU_FTR_HVMODE))
		return -EINVAL;

	/* POWER7 has 10-bit LPIDs (12-bit in POWER8) */
	host_lpid = mfspr(SPRN_LPID);
	rsvd_lpid = LPID_RSVD;

	kvmppc_init_lpid(rsvd_lpid + 1);

	kvmppc_claim_lpid(host_lpid);
	/* rsvd_lpid is reserved for use in partition switching */
	kvmppc_claim_lpid(rsvd_lpid);

	return 0;
}


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Paul Mackerras4984.48%480.00%


Scott Wood915.52%120.00%


Total58100.00%5100.00%






static void kvmppc_mmu_book3s_64_hv_reset_msr(struct kvm_vcpu *vcpu)
{
	unsigned long msr = vcpu->arch.intr_msr;

	/* If transactional, change to suspend mode on IRQ delivery */
	if (MSR_TM_TRANSACTIONAL(vcpu->arch.shregs.msr))
		msr |= MSR_TS_S;
	else
		msr |= vcpu->arch.shregs.msr & MSR_TS_MASK;
	kvmppc_set_msr(vcpu, msr);
}


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Michael Neuling4067.80%133.33%


Paul Mackerras1525.42%133.33%


Anton Blanchard46.78%133.33%


Total59100.00%3100.00%






static long kvmppc_virtmode_do_h_enter(struct kvm *kvm, unsigned long flags,
				long pte_index, unsigned long pteh,
				unsigned long ptel, unsigned long *pte_idx_ret)
{
	long ret;

	/* Protect linux PTE lookup from page table destruction */
	rcu_read_lock_sched();	/* this disables preemption too */
	ret = kvmppc_do_h_enter(kvm, flags, pte_index, pteh, ptel,
				current->mm->pgd, false, pte_idx_ret);
	rcu_read_unlock_sched();
	if (ret == H_TOO_HARD) {
		/* this can't happen */
		pr_err("KVM: Oops, kvmppc_h_enter returned too hard!\n");
		ret = H_RESOURCE;	/* or something */
	}
	return ret;

}


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Paul Mackerras8898.88%787.50%


Daniel Axtens11.12%112.50%


Total89100.00%8100.00%






static struct kvmppc_slb *kvmppc_mmu_book3s_hv_find_slbe(struct kvm_vcpu *vcpu,
							 gva_t eaddr)
{
	u64 mask;
	int i;

	for (i = 0; i < vcpu->arch.slb_nr; i++) {
		if (!(vcpu->arch.slb[i].orige & SLB_ESID_V))
			continue;

		if (vcpu->arch.slb[i].origv & SLB_VSID_B_1T)
			mask = ESID_MASK_1T;
		else
			mask = ESID_MASK;

		if (((vcpu->arch.slb[i].orige ^ eaddr) & mask) == 0)
			return &vcpu->arch.slb[i];
	}
	return NULL;
}


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Paul Mackerras121100.00%1100.00%


Total121100.00%1100.00%






static unsigned long kvmppc_mmu_get_real_addr(unsigned long v, unsigned long r,
			unsigned long ea)
{
	unsigned long ra_mask;

	ra_mask = hpte_page_size(v, r) - 1;
	return (r & HPTE_R_RPN & ~ra_mask) | (ea & ra_mask);
}


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Paul Mackerras50100.00%1100.00%


Total50100.00%1100.00%






static int kvmppc_mmu_book3s_64_hv_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
			struct kvmppc_pte *gpte, bool data, bool iswrite)
{
	struct kvm *kvm = vcpu->kvm;
	struct kvmppc_slb *slbe;
	unsigned long slb_v;
	unsigned long pp, key;
	unsigned long v, orig_v, gr;
	__be64 *hptep;
	int index;
	int virtmode = vcpu->arch.shregs.msr & (data ? MSR_DR : MSR_IR);

	/* Get SLB entry */
	if (virtmode) {
		slbe = kvmppc_mmu_book3s_hv_find_slbe(vcpu, eaddr);
		if (!slbe)
			return -EINVAL;
		slb_v = slbe->origv;
	} else {
		/* real mode access */
		slb_v = vcpu->kvm->arch.vrma_slb_v;
	}

	preempt_disable();
	/* Find the HPTE in the hash table */
	index = kvmppc_hv_find_lock_hpte(kvm, eaddr, slb_v,
					 HPTE_V_VALID | HPTE_V_ABSENT);
	if (index < 0) {
		preempt_enable();
		return -ENOENT;
	}
	hptep = (__be64 *)(kvm->arch.hpt.virt + (index << 4));
	v = orig_v = be64_to_cpu(hptep[0]) & ~HPTE_V_HVLOCK;
	if (cpu_has_feature(CPU_FTR_ARCH_300))
		v = hpte_new_to_old_v(v, be64_to_cpu(hptep[1]));
	gr = kvm->arch.hpt.rev[index].guest_rpte;

	unlock_hpte(hptep, orig_v);
	preempt_enable();

	gpte->eaddr = eaddr;
	gpte->vpage = ((v & HPTE_V_AVPN) << 4) | ((eaddr >> 12) & 0xfff);

	/* Get PP bits and key for permission check */
	pp = gr & (HPTE_R_PP0 | HPTE_R_PP);
	key = (vcpu->arch.shregs.msr & MSR_PR) ? SLB_VSID_KP : SLB_VSID_KS;
	key &= slb_v;

	/* Calculate permissions */
	gpte->may_read = hpte_read_permission(pp, key);
	gpte->may_write = hpte_write_permission(pp, key);
	gpte->may_execute = gpte->may_read && !(gr & (HPTE_R_N | HPTE_R_G));

	/* Storage key permission check for POWER7 */
	if (data && virtmode) {
		int amrfield = hpte_get_skey_perm(gr, vcpu->arch.amr);
		if (amrfield & 1)
			gpte->may_read = 0;
		if (amrfield & 2)
			gpte->may_write = 0;
	}

	/* Get the guest physical address */
	gpte->raddr = kvmppc_mmu_get_real_addr(v, gr, eaddr);
	return 0;
}


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Paul Mackerras38893.49%450.00%


pingfan liu112.65%112.50%


Alexander Graf71.69%112.50%


David Gibson61.45%112.50%


Aneesh Kumar K.V30.72%112.50%


Total415100.00%8100.00%



/*
 * Quick test for whether an instruction is a load or a store.
 * If the instruction is a load or a store, then this will indicate
 * which it is, at least on server processors.  (Embedded processors
 * have some external PID instructions that don't follow the rule
 * embodied here.)  If the instruction isn't a load or store, then
 * this doesn't return anything useful.
 */



static int instruction_is_store(unsigned int instr)
{
	unsigned int mask;

	mask = 0x10000000;
	if ((instr & 0xfc000000) == 0x7c000000)
		mask = 0x100;		/* major opcode 31 */
	return (instr & mask) != 0;
}


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Paul Mackerras42100.00%1100.00%


Total42100.00%1100.00%






int kvmppc_hv_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu,
			   unsigned long gpa, gva_t ea, int is_store)
{
	u32 last_inst;

	/*
         * If we fail, we just return to the guest and try executing it again.
         */
	if (kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst) !=
		EMULATE_DONE)
		return RESUME_GUEST;

	/*
         * WARNING: We do not know for sure whether the instruction we just
         * read from memory is the same that caused the fault in the first
         * place.  If the instruction we read is neither an load or a store,
         * then it can't access memory, so we don't need to worry about
         * enforcing access permissions.  So, assuming it is a load or
         * store, we just check that its direction (load or store) is
         * consistent with the original fault, since that's what we
         * checked the access permissions against.  If there is a mismatch
         * we just return and retry the instruction.
         */

	if (instruction_is_store(last_inst) != !!is_store)
		return RESUME_GUEST;

	/*
         * Emulated accesses are emulated by looking at the hash for
         * translation once, then performing the access later. The
         * translation could be invalidated in the meantime in which
         * point performing the subsequent memory access on the old
         * physical address could possibly be a security hole for the
         * guest (but not the host).
         *
         * This is less of an issue for MMIO stores since they aren't
         * globally visible. It could be an issue for MMIO loads to
         * a certain extent but we'll ignore it for now.
         */

	vcpu->arch.paddr_accessed = gpa;
	vcpu->arch.vaddr_accessed = ea;
	return kvmppc_emulate_mmio(run, vcpu);
}


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Paul Mackerras7182.56%133.33%


Alexander Graf1112.79%133.33%


Mihai Caraman44.65%133.33%


Total86100.00%3100.00%






int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
				unsigned long ea, unsigned long dsisr)
{
	struct kvm *kvm = vcpu->kvm;
	unsigned long hpte[3], r;
	unsigned long hnow_v, hnow_r;
	__be64 *hptep;
	unsigned long mmu_seq, psize, pte_size;
	unsigned long gpa_base, gfn_base;
	unsigned long gpa, gfn, hva, pfn;
	struct kvm_memory_slot *memslot;
	unsigned long *rmap;
	struct revmap_entry *rev;
	struct page *page, *pages[1];
	long index, ret, npages;
	bool is_ci;
	unsigned int writing, write_ok;
	struct vm_area_struct *vma;
	unsigned long rcbits;
	long mmio_update;

	if (kvm_is_radix(kvm))
		return kvmppc_book3s_radix_page_fault(run, vcpu, ea, dsisr);

	/*
         * Real-mode code has already searched the HPT and found the
         * entry we're interested in.  Lock the entry and check that
         * it hasn't changed.  If it has, just return and re-execute the
         * instruction.
         */
	if (ea != vcpu->arch.pgfault_addr)
		return RESUME_GUEST;

	if (vcpu->arch.pgfault_cache) {
		mmio_update = atomic64_read(&kvm->arch.mmio_update);
		if (mmio_update == vcpu->arch.pgfault_cache->mmio_update) {
			r = vcpu->arch.pgfault_cache->rpte;
			psize = hpte_page_size(vcpu->arch.pgfault_hpte[0], r);
			gpa_base = r & HPTE_R_RPN & ~(psize - 1);
			gfn_base = gpa_base >> PAGE_SHIFT;
			gpa = gpa_base | (ea & (psize - 1));
			return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea,
						dsisr & DSISR_ISSTORE);
		}
	}
	index = vcpu->arch.pgfault_index;
	hptep = (__be64 *)(kvm->arch.hpt.virt + (index << 4));
	rev = &kvm->arch.hpt.rev[index];
	preempt_disable();
	while (!try_lock_hpte(hptep, HPTE_V_HVLOCK))
		cpu_relax();
	hpte[0] = be64_to_cpu(hptep[0]) & ~HPTE_V_HVLOCK;
	hpte[1] = be64_to_cpu(hptep[1]);
	hpte[2] = r = rev->guest_rpte;
	unlock_hpte(hptep, hpte[0]);
	preempt_enable();

	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
		hpte[0] = hpte_new_to_old_v(hpte[0], hpte[1]);
		hpte[1] = hpte_new_to_old_r(hpte[1]);
	}
	if (hpte[0] != vcpu->arch.pgfault_hpte[0] ||
	    hpte[1] != vcpu->arch.pgfault_hpte[1])
		return RESUME_GUEST;

	/* Translate the logical address and get the page */
	psize = hpte_page_size(hpte[0], r);
	gpa_base = r & HPTE_R_RPN & ~(psize - 1);
	gfn_base = gpa_base >> PAGE_SHIFT;
	gpa = gpa_base | (ea & (psize - 1));
	gfn = gpa >> PAGE_SHIFT;
	memslot = gfn_to_memslot(kvm, gfn);

	trace_kvm_page_fault_enter(vcpu, hpte, memslot, ea, dsisr);

	/* No memslot means it's an emulated MMIO region */
	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
		return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea,
					      dsisr & DSISR_ISSTORE);

	/*
         * This should never happen, because of the slot_is_aligned()
         * check in kvmppc_do_h_enter().
         */
	if (gfn_base < memslot->base_gfn)
		return -EFAULT;

	/* used to check for invalidations in progress */
	mmu_seq = kvm->mmu_notifier_seq;
	smp_rmb();

	ret = -EFAULT;
	is_ci = false;
	pfn = 0;
	page = NULL;
	pte_size = PAGE_SIZE;
	writing = (dsisr & DSISR_ISSTORE) != 0;
	/* If writing != 0, then the HPTE must allow writing, if we get here */
	write_ok = writing;
	hva = gfn_to_hva_memslot(memslot, gfn);
	npages = get_user_pages_fast(hva, 1, writing, pages);
	if (npages < 1) {
		/* Check if it's an I/O mapping */
		down_read(&current->mm->mmap_sem);
		vma = find_vma(current->mm, hva);
		if (vma && vma->vm_start <= hva && hva + psize <= vma->vm_end &&
		    (vma->vm_flags & VM_PFNMAP)) {
			pfn = vma->vm_pgoff +
				((hva - vma->vm_start) >> PAGE_SHIFT);
			pte_size = psize;
			is_ci = pte_ci(__pte((pgprot_val(vma->vm_page_prot))));
			write_ok = vma->vm_flags & VM_WRITE;
		}
		up_read(&current->mm->mmap_sem);
		if (!pfn)
			goto out_put;
	} else {
		page = pages[0];
		pfn = page_to_pfn(page);
		if (PageHuge(page)) {
			page = compound_head(page);
			pte_size <<= compound_order(page);
		}
		/* if the guest wants write access, see if that is OK */
		if (!writing && hpte_is_writable(r)) {
			pte_t *ptep, pte;
			unsigned long flags;
			/*
                         * We need to protect against page table destruction
                         * hugepage split and collapse.
                         */
			local_irq_save(flags);
			ptep = find_current_mm_pte(current->mm->pgd,
						   hva,