/*
* 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 <linux/kvm_host.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/swap.h>
#include <linux/hugetlb.h>
#include <linux/compiler.h>
#include <linux/srcu.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/cmpxchg.h>
#include <asm/io.h>
#include <asm/vmx.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
#define pgprintk(x...) do { if (dbg) printk(x); } while (0)
#define rmap_printk(x...) do { if (dbg) printk(x); } while (0)
#else
#define pgprintk(x...) do { } while (0)
#define rmap_printk(x...) do { } while (0)
#endif
#ifdef MMU_DEBUG
static bool dbg = 0;
module_param(dbg, bool, 0644);
#endif
#ifndef MMU_DEBUG
#define ASSERT(x) do { } while (0)
#else
#define ASSERT(x) \
if (!(x)) { \
printk(KERN_WARNING "assertion failed %s:%d: %s\n", \
__FILE__, __LINE__, #x); \
}
#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 (((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 | PT_USER_MASK \
| PT64_NX_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)
#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
struct pte_list_desc {
u64 *sptes[PTE_LIST_EXT];
struct pte_list_desc *more;
};
struct kvm_shadow_walk_iterator {
u64 addr;
hpa_t shadow_addr;
u64 *sptep;
int level;
unsigned index;
};
#define for_each_shadow_entry(_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 void mmu_spte_set(u64 *sptep, u64 spte);
static void mmu_free_roots(struct kvm_vcpu *vcpu);
void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask)
{
shadow_mmio_mask = mmio_mask;
}
EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);
static void mark_mmio_spte(u64 *sptep, u64 gfn, unsigned access)
{
struct kvm_mmu_page *sp = page_header(__pa(sptep));
access &= ACC_WRITE_MASK | ACC_USER_MASK;
sp->mmio_cached = true;
trace_mark_mmio_spte(sptep, gfn, access);
mmu_spte_set(sptep, shadow_mmio_mask | access | gfn << PAGE_SHIFT);
}
static bool is_mmio_spte(u64 spte)
{
return (spte & shadow_mmio_mask) == shadow_mmio_mask;
}
static gfn_t get_mmio_spte_gfn(u64 spte)
{
return (spte & ~shadow_mmio_mask) >> PAGE_SHIFT;
}
static unsigned get_mmio_spte_access(u64 spte)
{
return (spte & ~shadow_mmio_mask) & ~PAGE_MASK;
}
static bool set_mmio_spte(u64 *sptep, gfn_t gfn, pfn_t pfn, unsigned access)
{
if (unlikely(is_noslot_pfn(pfn))) {
mark_mmio_spte(sptep, gfn, access);
return true;
}
return false;
}
static inline u64 rsvd_bits(int s, int e)
{
return ((1ULL << (e - s + 1)) - 1) << s;
}
void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
u64 dirty_mask, u64 nx_mask, u64 x_mask)
{
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;
}
EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes);
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 & PT_PRESENT_MASK && !is_mmio_spte(pte);
}
static int is_large_pte(u64 pte)
{
return pte & PT_PAGE_SIZE_MASK;
}
static int is_dirty_gpte(unsigned long pte)
{
return pte & PT_DIRTY_MASK;
}
static int is_rmap_spte(u64 pte)
{
return is_shadow_present_pte(pte);
}
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 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)
{
*sptep = spte;
}
static void __update_clear_spte_fast(u64 *sptep, u64 spte)
{
*sptep = spte;
}
static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
{
return xchg(sptep, spte);
}
static u64 __get_spte_lockless(u64 *sptep)
{
return ACCESS_ONCE(*sptep);
}
static bool __check_direct_spte_mmio_pf(u64 spte)
{
/* It is valid if the spte is zapped. */
return spte == 0ull;
}
#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();
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;
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).
* The difference is we can not catch the spte tlb flush if we leave
* guest mode, so we emulate it by increase clear_spte_count when spte
* is cleared.
*/
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;
}
static bool __check_direct_spte_mmio_pf(u64 spte)
{
union split_spte sspte = (union split_spte)spte;
u32 high_mmio_mask = shadow_mmio_mask >> 32;
/* It is valid if the spte is zapped. */
if (spte == 0ull)
return true;
/* It is valid if the spte is being zapped. */
if (sspte.spte_low == 0ull &&
(sspte.spte_high & high_mmio_mask) == high_mmio_mask)
return true;
return false;
}
#endif
static bool spte_is_locklessly_modifiable(u64 spte)
{
return (spte & (SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE)) ==
(SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE);
}
static bool spte_has_volatile_bits(u64 spte)
{
/*
* Always atomicly 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_is_locklessly_modifiable(spte))
return true;
if (!shadow_accessed_mask)
return false;
if (!is_shadow_present_pte(spte))
return false;
if ((spte & shadow_accessed_mask) &&
(!is_writable_pte(spte) || (spte & shadow_dirty_mask)))
return false;
return true;
}
static bool spte_is_bit_cleared(u64 old_spte, u64 new_spte, u64 bit_mask)
{
return (old_spte & bit_mask) && !(new_spte & bit_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);
}
/* Rules for using mmu_spte_update:
* Update the state bits, it means the mapped pfn is not changged.
*
* 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.
*/
static bool mmu_spte_update(u64 *sptep, u64 new_spte)
{
u64 old_spte = *sptep;
bool ret = false;
WARN_ON(!is_rmap_spte(new_spte));
if (!is_shadow_present_pte(old_spte)) {
mmu_spte_set(sptep, new_spte);
return ret;
}
if (!spte_has_volatile_bits(old_spte))
__update_clear_spte_fast(sptep, new_spte);
else
old_spte = __update_clear_spte_slow(sptep, new_spte);
/*
* For the spte updated out of mmu-lock is safe, since
* we always atomicly update it, see the comments in
* spte_has_volatile_bits().
*/
if (is_writable_pte(old_spte) && !is_writable_pte(new_spte))
ret = true;
if (!shadow_accessed_mask)
return ret;
if (spte_is_bit_cleared(old_spte, new_spte, shadow_accessed_mask))
kvm_set_pfn_accessed(spte_to_pfn(old_spte));
if (spte_is_bit_cleared(old_spte, new_spte, shadow_dirty_mask))
kvm_set_pfn_dirty(spte_to_pfn(old_spte));
return ret;
}
/*
* 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.
*/
static int mmu_spte_clear_track_bits(u64 *sptep)
{
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_rmap_spte(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_mmio_pfn(pfn) && !page_count(pfn_to_page(pfn)));
if (!shadow_accessed_mask || old_spte & shadow_accessed_mask)
kvm_set_pfn_accessed(pfn);
if (!shadow_dirty_mask || (old_spte & shadow_dirty_mask))
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 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();
vcpu->mode = READING_SHADOW_PAGE_TABLES;
/*
* Make sure a following spte read is not reordered ahead of the write
* to vcpu->mode.
*/
smp_mb();
}
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_commit_zap_page() can see us
* OUTSIDE_GUEST_MODE and proceed to free the shadow page table.
*/
smp_mb();
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 -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);
if (!page)
return -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 account_shadowed(struct kvm *kvm, gfn_t gfn)
{
struct kvm_memory_slot *slot;
struct kvm_lpage_info *linfo;
int i;
slot = gfn_to_memslot(kvm, gfn);
for (i = PT_DIRECTORY_LEVEL;
i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
linfo = lpage_info_slot(gfn, slot, i);
linfo->write_count += 1;
}
kvm->arch.indirect_shadow_pages++;
}
static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn)
{
struct kvm_memory_slot *slot;
struct kvm_lpage_info *linfo;
int i;
slot = gfn_to_memslot(kvm, gfn);
for (i = PT_DIRECTORY_LEVEL;
i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
linfo = lpage_info_slot(gfn, slot, i);
linfo->write_count -= 1;
WARN_ON(linfo->write_count < 0);
}
kvm->arch.indirect_shadow_pages--;
}
static int has_wrprotected_page(struct kvm *kvm,
gfn_t gfn,
int level)
{
struct kvm_memory_slot *slot;
struct kvm_lpage_info *linfo;
slot = gfn_to_memslot(kvm, gfn);
if (slot) {
linfo = lpage_info_slot(gfn, slot, level);
return linfo->write_count;
}
return 1;
}
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_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES); ++i) {
if (page_size >= KVM_HPAGE_SIZE(i))
ret = i;
else
break;
}
return ret;
}
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 = gfn_to_memslot(vcpu->kvm, gfn);
if (!slot || slot->flags & KVM_MEMSLOT_INVALID ||
(no_dirty_log && slot->dirty_bitmap))
slot = NULL;
return slot;
}
static bool mapping_level_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t large_gfn)
{
return !gfn_to_memslot_dirty_bitmap(vcpu, large_gfn, true);
}
static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn)
{
int host_level, level, max_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 (has_wrprotected_page(vcpu->kvm, large_gfn, level))
break;
return level - 1;
}
/*
* Pte mapping structures:
*
* If pte_list bit zero is zero, then pte_list point to the spte.
*
* If pte_list bit zero is one, (then pte_list & ~1) points to a struct
* pte_list_desc containing more mappings.
*
* Returns the number of pte entries before the spte was added or zero if
* the spte was not added.
*
*/
static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
unsigned long *pte_list)
{
struct pte_list_desc *desc;
int i, count = 0;
if (!*pte_list) {
rmap_printk("pte_list_add: %p %llx 0->1\n", spte, *spte);
*pte_list = (unsigned long)spte;
} else if (!(*pte_list & 1)) {
rmap_printk("pte_list_add: %p %llx 1->many\n", spte, *spte);
desc = mmu_alloc_pte_list_desc(vcpu);
desc->sptes[0] = (u64 *)*pte_list;
desc->sptes[1] = spte;
*pte_list = (unsigned long)desc | 1;
++count;
} else {
rmap_printk("pte_list_add: %p %llx many->many\n", spte, *spte);
desc = (struct pte_list_desc *)(*pte_list & ~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(unsigned long *pte_list, 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)
*pte_list = (unsigned long)desc->sptes[0];
else
if (prev_desc)
prev_desc->more = desc->more;
else
*pte_list = (unsigned long)desc->more | 1;
mmu_free_pte_list_desc(desc);
}
static void pte_list_remove(u64 *spte, unsigned long *pte_list)
{
struct pte_list_desc *desc;
struct pte_list_desc *prev_desc;
int i;
if (!*pte_list) {
printk(KERN_ERR "pte_list_remove: %p 0->BUG\n", spte);
BUG();
} else if (!(*pte_list & 1)) {
rmap_printk("pte_list_remove: %p 1->0\n", spte);
if ((u64 *)*pte_list != spte) {
printk(KERN_ERR "pte_list_remove: %p 1->BUG\n", spte);
BUG();
}
*pte_list = 0;
} else {
rmap_printk("pte_list_remove: %p many->many\n", spte);
desc = (struct pte_list_desc *)(*pte_list & ~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(pte_list,
desc, i,
prev_desc);
return;
}
prev_desc = desc;
desc = desc->more;
}
pr_err("pte_list_remove: %p many->many\n", spte);
BUG();
}
}
typedef void (*pte_list_walk_fn) (u64 *spte);
static void pte_list_walk(unsigned long *pte_list, pte_list_walk_fn fn)
{
struct pte_list_desc *desc;
int i;
if (!*pte_list)
return;
if (!(*pte_list & 1))
return fn((u64 *)*pte_list);
desc = (struct pte_list_desc *)(*pte_list & ~1ul);
while (desc) {
for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
fn(desc->sptes[i]);
desc = desc->more;
}
}
static unsigned long *__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];
}
/*
* Take gfn and return the reverse mapping to it.
*/
static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int level)
{
struct kvm_memory_slot *slot;
slot = gfn_to_memslot(kvm, gfn);
return __gfn_to_rmap(gfn, 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;
unsigned long *rmapp;
sp = page_header(__pa(spte));
kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level);
return pte_list_add(vcpu, spte, rmapp);
}
static void rmap_remove(struct kvm *kvm, u64 *spte)
{
struct kvm_mmu_page *sp;
gfn_t gfn;
unsigned long *rmapp;
sp = page_header(__pa(spte));
gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
rmapp = gfn_to_rmap(kvm, gfn, sp->role.level);
pte_list_remove(spte, rmapp);
}
/*
* 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(unsigned long rmap, struct rmap_iterator *iter)
{
if (!rmap)
return NULL;
if (!(rmap & 1)) {
iter->desc = NULL;
return (u64 *)rmap;
}
iter->desc = (struct pte_list_desc *)(rmap & ~1ul);
iter->pos = 0;
return iter->desc->sptes[iter->pos];
}
/*
* 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)
{
if (iter->desc) {
if (iter->pos < PTE_LIST_EXT - 1) {
u64 *sptep;
++iter->pos;
sptep = iter->desc->sptes[iter->pos];
if (sptep)
return sptep;
}
iter->desc = iter->desc->more;
if (iter->desc) {
iter->pos = 0;
/* desc->sptes[0] cannot be NULL */
return iter->desc->sptes[iter->pos];
}
}
return NULL;
}
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 writ-protection is caused by protecting shadow page table.
* @flush indicates whether tlb need be flushed.
*
* Note: write protection is difference between drity 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 the spte is dropped.
*/
static bool
spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush, bool pt_protect)
{
u64 spte = *sptep;
if (!is_writable_pte(spte) &&
!(pt_protect && spte_is_locklessly_modifiable(spte)))
return false;
rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
if (__drop_large_spte(kvm, sptep)) {
*flush |= true;
return true;
}
if (pt_protect)
spte &= ~SPTE_MMU_WRITEABLE;
spte = spte & ~PT_WRITABLE_MASK;
*flush |= mmu_spte_update(sptep, spte);
return false;
}
static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
bool pt_protect)
{
u64 *sptep;
struct rmap_iterator iter;
bool flush = false;
for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
BUG_ON(!(*sptep & PT_PRESENT_MASK));
if (spte_write_protect(kvm, sptep, &flush, pt_protect)) {
sptep = rmap_get_first(*rmapp, &iter);
continue;
}
sptep = rmap_get_next(&iter);
}
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.
*/
void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
struct kvm_memory_slot *slot,
gfn_t gfn_offset, unsigned long mask)
{
unsigned long *rmapp;
while (mask) {
rmapp = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
PT_PAGE_TABLE_LEVEL, slot);
__rmap_write_protect(kvm, rmapp, false);
/* clear the first set bit */
mask &= mask - 1;
}
}
static bool rmap_write_protect(struct kvm *kvm, u64 gfn)
{
struct kvm_memory_slot *slot;
unsigned long *rmapp;
int i;
bool write_protected = false;
slot = gfn_to_memslot(kvm, gfn);
for (i = PT_PAGE_TABLE_LEVEL;
i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
rmapp = __gfn_to_rmap(gfn, i, slot);
write_protected |= __rmap_write_protect(kvm, rmapp, true);
}
return write_protected;
}
static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
struct kvm_memory_slot *slot, unsigned long data)
{
u64 *sptep;
struct rmap_iterator iter;
int need_tlb_flush = 0;
while ((sptep = rmap_get_first(*rmapp, &iter))) {
BUG_ON(!(*sptep & PT_PRESENT_MASK));
rmap_printk("kvm_rmap_unmap_hva: spte %p %llx\n", sptep, *sptep);
drop_spte(kvm, sptep);
need_tlb_flush = 1;
}
return need_tlb_flush;
}
static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
struct kvm_memory_slot *slot, unsigned long data)
{
u64 *sptep;
struct rmap_iterator iter;
int need_flush = 0;
u64 new_spte;
pte_t *ptep = (pte_t *)data;
pfn_t new_pfn;
WARN_ON(pte_huge(*ptep));
new_pfn = pte_pfn(*ptep);
for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
BUG_ON(!is_shadow_present_pte(*sptep));
rmap_printk("kvm_set_pte_rmapp: spte %p %llx\n", sptep, *sptep);
need_flush = 1;
if (pte_write(*ptep)) {
drop_spte(kvm, sptep);
sptep = rmap_get_first(*rmapp, &iter);
} 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 &= ~shadow_accessed_mask;
mmu_spte_clear_track_bits(sptep);
mmu_spte_set(sptep, new_spte);
sptep = rmap_get_next(&iter);
}
}
if (need_flush)
kvm_flush_remote_tlbs(kvm);
return 0;
}
static int kvm_handle_hva_range(struct kvm *kvm,
unsigned long start,
unsigned long end,
unsigned long data,
int (*handler)(struct kvm *kvm,
unsigned long *rmapp,
struct kvm_memory_slot *slot,
unsigned long data))
{
int j;
int ret = 0;
struct kvm_memslots *slots;
struct kvm_memory_slot *memslot;
slots = kvm_memslots(kvm);
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 (j = PT_PAGE_TABLE_LEVEL;
j < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++j) {
unsigned long idx, idx_end;
unsigned long *rmapp;
/*
* {idx(page_j) | page_j intersects with
* [hva_start, hva_end)} = {idx, idx+1, ..., idx_end}.
*/
idx = gfn_to_index(gfn_start, memslot->base_gfn, j);
idx_end = gfn_to_index(gfn_end - 1, memslot->base_gfn, j);
rmapp = __gfn_to_rmap(gfn_start, j, memslot);
for (; idx <= idx_end; ++idx)
ret |= handler(kvm, rmapp++, memslot, data);
}
}
return ret;
}
static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
unsigned long data,
int (*handler)(struct kvm *kvm, unsigned long *rmapp,
struct kvm_memory_slot *slot,
unsigned long data))
{
return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler);
}
int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
{
return kvm_handle_hva(kvm, hva, 0, kvm_unmap_rmapp);
}
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, unsigned long *rmapp,
struct kvm_memory_slot *slot, unsigned long data)
{
u64 *sptep;
struct rmap_iterator uninitialized_var(iter);
int young = 0;
/*
* In case of absence of EPT Access and Dirty Bits supports,
* emulate the accessed bit for EPT, by checking if this page has
* an EPT mapping, and clearing it if it does. On the next access,
* a new EPT mapping will be established.
* This has some overhead, but not as much as the cost of swapping
* out actively used pages or breaking up actively used hugepages.
*/
if (!shadow_accessed_mask) {
young = kvm_unmap_rmapp(kvm, rmapp, slot, data);
goto out;
}
for (sptep = rmap_get_first(*rmapp, &iter); sptep;
sptep = rmap_get_next(&iter)) {
BUG_ON(!is_shadow_present_pte(*sptep));
if (*sptep & shadow_accessed_mask) {
young = 1;
clear_bit((ffs(shadow_accessed_mask) - 1),
(unsigned long *)sptep);
}
}
out:
/* @data has hva passed to kvm_age_hva(). */
trace_kvm_age_page(data, slot, young);
return young;
}
static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
struct kvm_memory_slot *slot, unsigned long data)
{
u64 *sptep;
struct rmap_iterator iter;
int young = 0;
/*
* If there's no access bit in the secondary pte set by the
* hardware it's up to gup-fast/gup to set the access bit in
* the primary pte or in the page structure.
*/
if (!shadow_accessed_mask)
goto out;
for (sptep = rmap_get_first(*rmapp, &iter); sptep;
sptep = rmap_get_next(&iter)) {
BUG_ON(!is_shadow_present_pte(*sptep));
if (*sptep & shadow_accessed_mask) {
young = 1;
break;
}
}
out:
return young;
}
#define RMAP_RECYCLE_THRESHOLD 1000
static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
{
unsigned long *rmapp;
struct kvm_mmu_page *sp;
sp = page_header(__pa(spte));
rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level);
kvm_unmap_rmapp(vcpu->kvm, rmapp, NULL, 0);
kvm_flush_remote_tlbs(vcpu->kvm);
}
int kvm_age_hva(struct kvm *kvm, unsigned long hva)
{
return kvm_handle_hva(kvm, hva, hva, 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)
{
ASSERT(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 gfn & ((1 << KVM_MMU_HASH_SHIFT) - 1);
}
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,
u64 *parent_pte, 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);
list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
sp->parent_ptes = 0;
mmu_page_add_parent_pte(vcpu, sp, parent_pte);
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)
{
pte_list_walk(&sp->parent_ptes, mark_unsync);
}
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 1;
}
static void nonpaging_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
{
}
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 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))
goto clear_child_bitmap;
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)
goto clear_child_bitmap;
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
goto clear_child_bitmap;
continue;
clear_child_bitmap:
__clear_bit(i, sp->unsync_child_bitmap);
sp->unsync_children--;
WARN_ON((int)sp->unsync_children < 0);
}
return nr_unsync_leaf;
}
static int mmu_unsync_walk(struct kvm_mmu_page *sp,
struct kvm_mmu_pages *pvec)
{
if (!sp->unsync_children)
return 0;
mmu_pages_add(pvec, sp, 0);
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);
#define for_each_gfn_sp(_kvm, _sp, _gfn) \
hlist_for_each_entry(_sp, \
&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
if ((_sp)->gfn != (_gfn)) {} else
#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \
for_each_gfn_sp(_kvm, _sp, _gfn) \
if ((_sp)->role.direct || (_sp)->role.invalid) {} else
/* @sp->gfn should be write-protected at the call site */
static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list, bool clear_unsync)
{
if (sp->role.cr4_pae != !!is_pae(vcpu)) {
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
return 1;
}
if (clear_unsync)
kvm_unlink_unsync_page(vcpu->kvm, sp);
if (vcpu->arch.mmu.sync_page(vcpu, sp)) {
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
return 1;
}
kvm_mmu_flush_tlb(vcpu);
return 0;
}
static int kvm_sync_page_transient(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
LIST_HEAD(invalid_list);
int ret;
ret = __kvm_sync_page(vcpu, sp, &invalid_list, false);
if (ret)
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
return ret;
}
#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 int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list)
{
return __kvm_sync_page(vcpu, sp, invalid_list, true);
}
/* @gfn should be write-protected at the call site */
static void kvm_sync_pages(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct kvm_mmu_page *s;
LIST_HEAD(invalid_list);
bool flush = false;
for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) {
if (!s->unsync)
continue;
WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
kvm_unlink_unsync_page(vcpu->kvm, s);
if ((s->role.cr4_pae != !!is_pae(vcpu)) ||
(vcpu->arch.mmu.sync_page(vcpu, s))) {
kvm_mmu_prepare_zap_page(vcpu->kvm, s, &invalid_list);
continue;
}
flush = true;
}
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
if (flush)
kvm_mmu_flush_tlb(vcpu);
}
struct mmu_page_path {
struct kvm_mmu_page *parent[PT64_ROOT_LEVEL-1];
unsigned int idx[PT64_ROOT_LEVEL-1];
};
#define for_each_sp(pvec, sp, parents, i) \
for (i = mmu_pages_next(&pvec, &parents, -1), \
sp = pvec.page[i].sp; \
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;
if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
parents->idx[0] = pvec->page[n].idx;
return n;
}
parents->parent[sp->role.level-2] = sp;
parents->idx[sp->role.level-1] = pvec->page[n].idx;
}
return n;
}
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;
--sp->unsync_children;
WARN_ON((int)sp->unsync_children < 0);
__clear_bit(idx, sp->unsync_child_bitmap);
level++;
} while (level < PT64_ROOT_LEVEL-1 && !sp->unsync_children);
}
static void kvm_mmu_pages_init(struct kvm_mmu_page *parent,
struct mmu_page_path *parents,
struct kvm_mmu_pages *pvec)
{
parents->parent[parent->role.level-1] = NULL;
pvec->nr = 0;
}
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);
kvm_mmu_pages_init(parent, &parents, &pages);
while (mmu_unsync_walk(parent, &pages)) {
bool protected = false;
for_each_sp(pages, sp, parents, i)
protected |= rmap_write_protect(vcpu->kvm, sp->gfn);
if (protected)
kvm_flush_remote_tlbs(vcpu->kvm);
for_each_sp(pages, sp, parents, i) {
kvm_sync_page(vcpu, sp, &invalid_list);
mmu_pages_clear_parents(&parents);
}
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
cond_resched_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_pages_init(parent, &parents, &pages);
}
}
static void init_shadow_page_table(struct kvm_mmu_page *sp)
{
int i;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
sp->spt[i] = 0ull;
}
static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp)
{
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,
u64 *parent_pte)
{
union kvm_mmu_page_role role;
unsigned quadrant;
struct kvm_mmu_page *sp;
bool need_sync = false;
role = vcpu->arch.mmu.base_role;
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_gfn_sp(vcpu->kvm, sp, gfn) {
if (!need_sync && sp->unsync)
need_sync = true;
if (sp->role.word != role.word)
continue;
if (sp->unsync && kvm_sync_page_transient(vcpu, sp))
break;
mmu_page_add_parent_pte(vcpu, sp, parent_pte);
if (sp->unsync_children) {
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
kvm_mmu_mark_parents_unsync(sp);
} else if (sp->unsync)
kvm_mmu_mark_parents_unsync(sp);
__clear_sp_write_flooding_count(sp);
trace_kvm_mmu_get_page(sp, false);
return sp;
}
++vcpu->kvm->stat.mmu_cache_miss;
sp = kvm_mmu_alloc_page(vcpu, parent_pte, direct);
if (!sp)
return sp;
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) {
if (rmap_write_protect(vcpu->kvm, gfn))
kvm_flush_remote_tlbs(vcpu->kvm);
if (level > PT_PAGE_TABLE_LEVEL && need_sync)
kvm_sync_pages(vcpu, gfn);
account_shadowed(vcpu->kvm, gfn);
}
init_shadow_page_table(sp);
trace_kvm_mmu_get_page(sp, true);
return sp;
}
static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator,
struct kvm_vcpu *vcpu, u64 addr)
{
iterator->addr = addr;
iterator->shadow_addr = vcpu->arch.mmu.root_hpa;
iterator->level = vcpu->arch.mmu.shadow_root_level;
if (iterator->level == PT64_ROOT_LEVEL &&
vcpu->arch.mmu.root_level < PT64_ROOT_LEVEL &&
!vcpu->arch.mmu.direct_map)
--iterator->level;
if (iterator->level == PT32E_ROOT_LEVEL) {
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 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)
{
return __shadow_walk_next(iterator, *iterator->sptep);
}
static void link_shadow_page(u64 *sptep, struct kvm_mmu_page *sp)
{
u64 spte;
spte = __pa(sp->spt) | PT_PRESENT_MASK | PT_WRITABLE_MASK |
shadow_user_mask | shadow_x_mask | shadow_accessed_mask;
mmu_spte_set(sptep, spte);
}
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_put_page(struct kvm_mmu_page *sp, u64 *parent_pte)
{
mmu_page_remove_parent_pte(sp, parent_pte);
}
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;
kvm_mmu_pages_init(parent, &parents, &pages);
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++;
}
kvm_mmu_pages_init(parent, &parents, &pages);
}
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->gfn);
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);
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;
/*
* wmb: make sure everyone sees our modifications to the page tables
* rmb: make sure we see changes to vcpu->mode
*/
smp_mb();
/*
* Wait 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_entry(kvm->arch.active_mmu_pages.prev,
struct kvm_mmu_page, link);
kvm_mmu_prepare_zap_page(kvm, sp, invalid_list);
return true;
}
/*
* 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);
/*
* The function is based on mtrr_type_lookup() in
* arch/x86/kernel/cpu/mtrr/generic.c
*/
static int get_mtrr_type(struct mtrr_state_type *mtrr_state,
u64 start, u64 end)
{
int i;
u64 base, mask;
u8 prev_match, curr_match;
int num_var_ranges = KVM_NR_VAR_MTRR;
if (!mtrr_state->enabled)
return 0xFF;
/* Make end inclusive end, instead of exclusive */
end--;
/* Look in fixed ranges. Just return the type as per start */
if (mtrr_state->have_fixed && (start < 0x100000)) {
int idx;
if (start < 0x80000) {
idx = 0;
idx += (start >> 16);
return mtrr_state->fixed_ranges[idx];
} else if (start < 0xC0000) {
idx = 1 * 8;
idx += ((start - 0x80000) >> 14);
return mtrr_state->fixed_ranges[idx];
} else if (start < 0x1000000) {
idx = 3 * 8;
idx += ((start - 0xC0000) >> 12);
return mtrr_state->fixed_ranges[idx];
}
}
/*
* Look in variable ranges
* Look of multiple ranges matching this address and pick type
* as per MTRR precedence
*/
if (!(mtrr_state->enabled & 2))
return mtrr_state->def_type;
prev_match = 0xFF;
for (i = 0; i < num_var_ranges; ++i) {
unsigned short start_state, end_state;
if (!(mtrr_state->var_ranges[i].mask_lo & (1 << 11)))
continue;
base = (((u64)mtrr_state->var_ranges[i].base_hi) << 32) +
(mtrr_state->var_ranges[i].base_lo & PAGE_MASK);
mask = (((u64)mtrr_state->var_ranges[i].mask_hi) << 32) +
(mtrr_state->var_ranges[i].mask_lo & PAGE_MASK);
start_state = ((start & mask) == (base & mask));
end_state = ((end & mask) == (base & mask));
if (start_state != end_state)
return 0xFE;
if ((start & mask) != (base & mask))
continue;
curr_match = mtrr_state->var_ranges[i].base_lo & 0xff;
if (prev_match == 0xFF) {
prev_match = curr_match;
continue;
}
if (prev_match == MTRR_TYPE_UNCACHABLE ||
curr_match == MTRR_TYPE_UNCACHABLE)
return MTRR_TYPE_UNCACHABLE;
if ((prev_match == MTRR_TYPE_WRBACK &&
curr_match == MTRR_TYPE_WRTHROUGH) ||
(prev_match == MTRR_TYPE_WRTHROUGH &&
curr_match == MTRR_TYPE_WRBACK)) {
prev_match = MTRR_TYPE_WRTHROUGH;
curr_match = MTRR_TYPE_WRTHROUGH;
}
if (prev_match != curr_match)
return MTRR_TYPE_UNCACHABLE;
}
if (prev_match != 0xFF)
return prev_match;
return mtrr_state->def_type;
}
u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
{
u8 mtrr;
mtrr = get_mtrr_type(&vcpu->arch.mtrr_state, gfn << PAGE_SHIFT,
(gfn << PAGE_SHIFT) + PAGE_SIZE);
if (mtrr == 0xfe || mtrr == 0xff)
mtrr = MTRR_TYPE_WRBACK;
return mtrr;
}
EXPORT_SYMBOL_GPL(kvm_get_guest_memory_type);
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 void kvm_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct kvm_mmu_page *s;
for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) {
if (s->unsync)
continue;
WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
__kvm_unsync_page(vcpu, s);
}
}
static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
bool can_unsync)
{
struct kvm_mmu_page *s;
bool need_unsync = false;
for_each_gfn_indirect_valid_sp(vcpu->kvm, s, gfn) {
if (!can_unsync)
return 1;
if (s->role.level != PT_PAGE_TABLE_LEVEL)
return 1;
if (!s->unsync)
need_unsync = true;
}
if (need_unsync)
kvm_unsync_pages(vcpu, gfn);
return 0;
}
static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
unsigned pte_access, int level,
gfn_t gfn, pfn_t pfn, bool speculative,
bool can_unsync, bool host_writable)
{
u64 spte;
int ret = 0;
if (set_mmio_spte(sptep, gfn, pfn, pte_access))
return 0;
spte = PT_PRESENT_MASK;
if (!speculative)
spte |= shadow_accessed_mask;
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;
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 &&
has_wrprotected_page(vcpu->kvm, 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 = 1;
pte_access &= ~ACC_WRITE_MASK;
spte &= ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE);
}
}
if (pte_access & ACC_WRITE_MASK)
mark_page_dirty(vcpu->kvm, gfn);
set_pte:
if (mmu_spte_update(sptep, spte))
kvm_flush_remote_tlbs(vcpu->kvm);
done:
return ret;
}
static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
unsigned pte_access, int write_fault, int *emulate,
int level, gfn_t gfn, pfn_t pfn, bool speculative,
bool host_writable)
{
int was_rmapped = 0;
int rmap_count;
pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
*sptep, write_fault, gfn);
if (is_rmap_spte(*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);
kvm_flush_remote_tlbs(vcpu->kvm);
} else if (pfn != spte_to_pfn(*sptep)) {
pgprintk("hfn old %llx new %llx\n",
spte_to_pfn(*sptep), pfn);
drop_spte(vcpu->kvm, sptep);
kvm_flush_remote_tlbs(vcpu->kvm);
} else
was_rmapped = 1;
}
if (set_spte(vcpu, sptep, pte_access, level, gfn, pfn, speculative,
true, host_writable)) {
if (write_fault)
*emulate = 1;
kvm_mmu_flush_tlb(vcpu);
}
if (unlikely(is_mmio_spte(*sptep) && emulate))
*emulate = 1;
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_PRESENT_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);
}
static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
}
static bool is_rsvd_bits_set(struct kvm_mmu *mmu, u64 gpte, int level)
{
int bit7;
bit7 = (gpte >> 7) & 1;
return (gpte & mmu->rsvd_bits_mask[bit7][level-1]) != 0;
}
static 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 bool prefetch_invalid_gpte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp, u64 *spte,
u64 gpte)
{
if (is_rsvd_bits_set(&vcpu->arch.mmu, gpte, PT_PAGE_TABLE_LEVEL))
goto no_present;
if (!is_present_gpte(gpte))
goto no_present;
if (!(gpte & PT_ACCESSED_MASK))
goto no_present;
return false;
no_present:
drop_spte(vcpu->kvm, spte);
return true;
}
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];
unsigned access = sp->role.access;
int i, ret;
gfn_t gfn;
gfn = kvm_mmu_page_get_gfn(sp, start - sp->spt);
if (!gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK))
return -1;
ret = gfn_to_page_many_atomic(vcpu->kvm, gfn, pages, end - start);
if (ret <= 0)
return -1;
for (i = 0; i < ret; i++, gfn++, start++)
mmu_set_spte(vcpu, start, access, 0, NULL,
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;
/*
* Since it's no accessed bit on EPT, it's no way to
* distinguish between actually accessed translations
* and prefetched, so disable pte prefetch if EPT is
* enabled.
*/
if (!shadow_accessed_mask)
return;
sp = page_header(__pa(sptep));
if (sp->role.level > PT_PAGE_TABLE_LEVEL)
return;
__direct_pte_prefetch(vcpu, sp, sptep);
}
static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
int map_writable, int level, gfn_t gfn, pfn_t pfn,
bool prefault)
{
struct kvm_shadow_walk_iterator iterator;
struct kvm_mmu_page *sp;
int emulate = 0;
gfn_t pseudo_gfn;
for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
if (iterator.level == level) {
mmu_set_spte(vcpu, iterator.sptep, ACC_ALL,
write, &emulate, level, gfn, pfn,
prefault, map_writable);
direct_pte_prefetch(vcpu, iterator.sptep);
++vcpu->stat.pf_fixed;
break;
}
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, iterator.sptep);
link_shadow_page(iterator.sptep, sp);
}
}
return emulate;
}
static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk)
{
siginfo_t info;
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_MCEERR_AR;
info.si_addr = (void __user *)address;
info.si_addr_lsb = PAGE_SHIFT;
send_sig_info(SIGBUS, &info, tsk);
}
static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, 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.
* Return 1 to tell kvm to emulate it.
*/
if (pfn == KVM_PFN_ERR_RO_FAULT)
return 1;
if (pfn == KVM_PFN_ERR_HWPOISON) {
kvm_send_hwpoison_signal(gfn_to_hva(vcpu->kvm, gfn), current);
return 0;
}
return -EFAULT;
}
static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
gfn_t *gfnp, pfn_t *pfnp, int *levelp)
{
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_mmio_pfn(pfn) &&
level == PT_PAGE_TABLE_LEVEL &&
PageTransCompound(pfn_to_page(pfn)) &&
!has_wrprotected_page(vcpu->kvm, 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,
pfn_t pfn, unsigned access, int *ret_val)
{
bool ret = true;
/* The pfn is invalid, report the error! */
if (unlikely(is_error_pfn(pfn))) {
*ret_val = kvm_handle_bad_page(vcpu, gfn, pfn);
goto exit;
}
if (unlikely(is_noslot_pfn(pfn)))
vcpu_cache_mmio_info(vcpu, gva, gfn, access);
ret = false;
exit:
return ret;
}
static bool page_fault_can_be_fast(struct kvm_vcpu *vcpu, u32 error_code)
{
/*
* #PF can be fast only if the shadow page table is present and it
* 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.
*/
if (!(error_code & PFERR_PRESENT_MASK) ||
!(error_code & PFERR_WRITE_MASK))
return false;
return true;
}
static bool
fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 spte)
{
struct kvm_mmu_page *sp = page_header(__pa(sptep));
gfn_t gfn;
WARN_ON(!sp->role.direct);
/*
* The gfn of direct spte is stable since it is calculated
* by sp->gfn.
*/
gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
if (cmpxchg64(sptep, spte, spte | PT_WRITABLE_MASK) == spte)
mark_page_dirty(vcpu->kvm, gfn);
return true;
}
/*
* 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;
bool ret = false;
u64 spte = 0ull;
if (!page_fault_can_be_fast(vcpu, error_code))
return false;
walk_shadow_page_lockless_begin(vcpu);
for_each_shadow_entry_lockless(vcpu, gva, iterator, spte)
if (!is_shadow_present_pte(spte) || iterator.level < level)
break;
/*
* If the mapping has been changed, let the vcpu fault on the
* same address again.
*/
if (!is_rmap_spte(spte)) {
ret = true;
goto exit;
}
if (!is_last_spte(spte, level))
goto exit;
/*
* Check if it is a spurious fault caused by TLB lazily flushed.
*
* Need not check the access of upper level table entries since
* they are always ACC_ALL.
*/
if (is_writable_pte(spte)) {
ret = true;
goto exit;
}
/*
* Currently, to simplify the code, only the spte write-protected
* by dirty-log can be fast fixed.
*/
if (!spte_is_locklessly_modifiable(spte))
goto exit;
/*
* 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.
*/
ret = fast_pf_fix_direct_spte(vcpu, iterator.sptep, spte);
exit:
trace_fast_page_fault(vcpu, gva, error_code, iterator.sptep,
spte, ret);
walk_shadow_page_lockless_end(vcpu);
return ret;
}
static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
gva_t gva, pfn_t *pfn, bool write, bool *writable);
static void 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;
int force_pt_level;
pfn_t pfn;
unsigned long mmu_seq;
bool map_writable, write = error_code & PFERR_WRITE_MASK;
force_pt_level = mapping_level_dirty_bitmap(vcpu, gfn);
if (likely(!force_pt_level)) {
level = mapping_level(vcpu, gfn);
/*
* 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);
} else
level = PT_PAGE_TABLE_LEVEL;
if (fast_page_fault(vcpu, v, level, error_code))
return 0;
mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
if (try_async_pf(vcpu, prefault, gfn, v, &pfn, write, &map_writable))
return 0;
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;
make_mmu_pages_available(vcpu);
if (likely(!force_pt_level))
transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
r = __direct_map(vcpu, v, 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 0;
}
static void mmu_free_roots(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_mmu_page *sp;
LIST_HEAD(invalid_list);
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;
spin_lock(&vcpu->kvm->mmu_lock);
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL &&
(vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL ||
vcpu->arch.mmu.direct_map)) {
hpa_t root = vcpu->arch.mmu.root_hpa;
sp = page_header(root);
--sp->root_count;
if (!sp->root_count && sp->role.invalid) {
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list);
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
}
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
spin_unlock(&vcpu->kvm->mmu_lock);
return;
}
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
if (root) {
root &= PT64_BASE_ADDR_MASK;
sp = page_header(root);
--sp->root_count;
if (!sp->root_count && sp->role.invalid)
kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
&invalid_list);
}
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
}
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}
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_LEVEL) {
spin_lock(&vcpu->kvm->mmu_lock);
make_mmu_pages_available(vcpu);
sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_LEVEL,
1, ACC_ALL, NULL);
++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];
ASSERT(!VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
make_mmu_pages_available(vcpu);
sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT),
i << 30,
PT32_ROOT_LEVEL, 1, ACC_ALL,
NULL);
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_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
ASSERT(!VALID_PAGE(root));
spin_lock(&vcpu->kvm->mmu_lock);
make_mmu_pages_available(vcpu);
sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL,
0, ACC_ALL, NULL);
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_LEVEL)
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];
ASSERT(!VALID_PAGE(root));
if (vcpu->arch.mmu.root_level == PT32E_ROOT_LEVEL) {
pdptr = vcpu->arch.mmu.get_pdptr(vcpu, i);
if (!is_present_gpte(pdptr)) {
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);
make_mmu_pages_available(vcpu);
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, 0,
ACC_ALL, NULL);
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_LEVEL) {
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);
}
static void 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, ~0ul);
kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
sp = page_header(root);
mmu_sync_children(vcpu, sp);
kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
return;
}
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);
}
void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
{
spin_lock(&vcpu->kvm->mmu_lock);
mmu_sync_roots(vcpu);
spin_unlock(&vcpu->kvm->mmu_lock);
}
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);
}
static bool quickly_check_mmio_pf(struct kvm_vcpu *vcpu, u64 addr, bool direct)
{
if (direct)
return vcpu_match_mmio_gpa(vcpu, addr);
return vcpu_match_mmio_gva(vcpu, addr);
}
/*
* On direct hosts, the last spte is only allows two states
* for mmio page fault:
* - It is the mmio spte
* - It is zapped or it is being zapped.
*
* This function completely checks the spte when the last spte
* is not the mmio spte.
*/
static bool check_direct_spte_mmio_pf(u64 spte)
{
return __check_direct_spte_mmio_pf(spte);
}
static u64 walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr)
{
struct kvm_shadow_walk_iterator iterator;
u64 spte = 0ull;
walk_shadow_page_lockless_begin(vcpu);
for_each_shadow_entry_lockless(vcpu, addr, iterator, spte)
if (!is_shadow_present_pte(spte))
break;
walk_shadow_page_lockless_end(vcpu);
return spte;
}
/*
* If it is a real mmio page fault, return 1 and emulat the instruction
* directly, return 0 to let CPU fault again on the address, -1 is
* returned if bug is detected.
*/
int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct)
{
u64 spte;
if (quickly_check_mmio_pf(vcpu, addr, direct))
return 1;
spte = walk_shadow_page_get_mmio_spte(vcpu, addr);
if (is_mmio_spte(spte)) {
gfn_t gfn = get_mmio_spte_gfn(spte);
unsigned access = get_mmio_spte_access(spte);
if (direct)
addr = 0;
trace_handle_mmio_page_fault(addr, gfn, access);
vcpu_cache_mmio_info(vcpu, addr, gfn, access);
return 1;
}
/*
* It's ok if the gva is remapped by other cpus on shadow guest,
* it's a BUG if the gfn is not a mmio page.
*/
if (direct && !check_direct_spte_mmio_pf(spte))
return -1;
/*
* If the page table is zapped by other cpus, let CPU fault again on
* the address.
*/
return 0;
}
EXPORT_SYMBOL_GPL(handle_mmio_page_fault_common);
static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr,
u32 error_code, bool direct)
{
int ret;
ret = handle_mmio_page_fault_common(vcpu, addr, direct);
WARN_ON(ret < 0);
return ret;
}
static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
u32 error_code, bool prefault)
{
gfn_t gfn;
int r;
pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code);
if (unlikely(error_code & PFERR_RSVD_MASK))
return handle_mmio_page_fault(vcpu, gva, error_code, true);
r = mmu_topup_memory_caches(vcpu);
if (r)
return r;
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
gfn = gva >> PAGE_SHIFT;
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, gfn, &arch);
}
static bool can_do_async_pf(struct kvm_vcpu *vcpu)
{
if (unlikely(!irqchip_in_kernel(vcpu->kvm) ||
kvm_event_needs_reinjection(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, pfn_t *pfn, bool write, bool *writable)
{
bool async;
*pfn = gfn_to_pfn_async(vcpu->kvm, gfn, &async, write, writable);
if (!async)
return false; /* *pfn has correct page already */
if (!prefault && 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_prot(vcpu->kvm, gfn, write, writable);
return false;
}
static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
bool prefault)
{
pfn_t pfn;
int r;
int level;
int force_pt_level;
gfn_t gfn = gpa >> PAGE_SHIFT;
unsigned long mmu_seq;
int write = error_code & PFERR_WRITE_MASK;
bool map_writable;
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
if (unlikely(error_code & PFERR_RSVD_MASK))
return handle_mmio_page_fault(vcpu, gpa, error_code, true);
r = mmu_topup_memory_caches(vcpu);
if (r)
return r;
force_pt_level = mapping_level_dirty_bitmap(vcpu, gfn);
if (likely(!force_pt_level)) {
level = mapping_level(vcpu, gfn);
gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
} else
level = PT_PAGE_TABLE_LEVEL;
if (fast_page_fault(vcpu, gpa, level, error_code))
return 0;
mmu_seq = vcpu->kvm->mmu_notifier_seq;
smp_rmb();
if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, write, &map_writable))
return 0;
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;
make_mmu_pages_available(vcpu);
if (likely(!force_pt_level))
transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
r = __direct_map(vcpu, gpa, 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 0;
}
static void nonpaging_free(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
}
static int nonpaging_init_context(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
context->new_cr3 = nonpaging_new_cr3;
context->page_fault = nonpaging_page_fault;
context->gva_to_gpa = nonpaging_gva_to_gpa;
context->free = nonpaging_free;
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->root_hpa = INVALID_PAGE;
context->direct_map = true;
context->nx = false;
return 0;
}
void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
{
++vcpu->stat.tlb_flush;
kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
}
static void paging_new_cr3(struct kvm_vcpu *vcpu)
{
pgprintk("%s: cr3 %lx\n", __func__, kvm_read_cr3(vcpu));
mmu_free_roots(vcpu);
}
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 void paging_free(struct kvm_vcpu *vcpu)
{
nonpaging_free(vcpu);
}
static inline void protect_clean_gpte(unsigned *access, unsigned gpte)
{
unsigned mask;
BUILD_BUG_ON(PT_WRITABLE_MASK != ACC_WRITE_MASK);
mask = (unsigned)~ACC_WRITE_MASK;
/* Allow write access to dirty gptes */
mask |= (gpte >> (PT_DIRTY_SHIFT - PT_WRITABLE_SHIFT)) & PT_WRITABLE_MASK;
*access &= mask;
}
static bool sync_mmio_spte(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(sptep, gfn, access);
return true;
}
return false;
}
static inline unsigned gpte_access(struct kvm_vcpu *vcpu, u64 gpte)
{
unsigned access;
access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK;
access &= ~(gpte >> PT64_NX_SHIFT);
return access;
}
static inline bool is_last_gpte(struct kvm_mmu *mmu, unsigned level, unsigned gpte)
{
unsigned index;
index = level - 1;
index |= (gpte & PT_PAGE_SIZE_MASK) >> (PT_PAGE_SIZE_SHIFT - 2);
return mmu->last_pte_bitmap & (1 << index);
}
#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 kvm_mmu *context)
{
int maxphyaddr = cpuid_maxphyaddr(vcpu);
u64 exb_bit_rsvd = 0;
if (!context->nx)
exb_bit_rsvd = rsvd_bits(63, 63);
switch (context->root_level) {
case PT32_ROOT_LEVEL:
/* no rsvd bits for 2 level 4K page table entries */
context->rsvd_bits_mask[0][1] = 0;
context->rsvd_bits_mask[0][0] = 0;
context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
if (!is_pse(vcpu)) {
context->rsvd_bits_mask[1][1] = 0;
break;
}
if (is_cpuid_PSE36())
/* 36bits PSE 4MB page */
context->rsvd_bits_mask[1][1] = rsvd_bits(17, 21);
else
/* 32 bits PSE 4MB page */
context->rsvd_bits_mask[1][1] = rsvd_bits(13, 21);
break;
case PT32E_ROOT_LEVEL:
context->rsvd_bits_mask[0][2] =
rsvd_bits(maxphyaddr, 63) |
rsvd_bits(7, 8) | rsvd_bits(1, 2); /* PDPTE */
context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 62); /* PDE */
context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 62); /* PTE */
context->rsvd_bits_mask[1][1] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 62) |
rsvd_bits(13, 20); /* large page */
context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
break;
case PT64_ROOT_LEVEL:
context->rsvd_bits_mask[0][3] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 8);
context->rsvd_bits_mask[0][2] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51) | rsvd_bits(7, 8);
context->rsvd_bits_mask[0][1] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[0][0] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51);
context->rsvd_bits_mask[1][3] = context->rsvd_bits_mask[0][3];
context->rsvd_bits_mask[1][2] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51) |
rsvd_bits(13, 29);
context->rsvd_bits_mask[1][1] = exb_bit_rsvd |
rsvd_bits(maxphyaddr, 51) |
rsvd_bits(13, 20); /* large page */
context->rsvd_bits_mask[1][0] = context->rsvd_bits_mask[0][0];
break;
}
}
static void update_permission_bitmask(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
{
unsigned bit, byte, pfec;
u8 map;
bool fault, x, w, u, wf, uf, ff, smep;
smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) {
pfec = byte << 1;
map = 0;
wf = pfec & PFERR_WRITE_MASK;
uf = pfec & PFERR_USER_MASK;
ff = pfec & PFERR_FETCH_MASK;
for (bit = 0; bit < 8; ++bit) {
x = bit & ACC_EXEC_MASK;
w = bit & ACC_WRITE_MASK;
u = bit & ACC_USER_MASK;
/* Not really needed: !nx will cause pte.nx to fault */
x |= !mmu->nx;
/* Allow supervisor writes if !cr0.wp */
w |= !is_write_protection(vcpu) && !uf;
/* Disallow supervisor fetches of user code if cr4.smep */
x &= !(smep && u && !uf);
fault = (ff && !x) || (uf && !u) || (wf && !w);
map |= fault << bit;
}
mmu->permissions[byte] = map;
}
}
static void update_last_pte_bitmap(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
{
u8 map;
unsigned level, root_level = mmu->root_level;
const unsigned ps_set_index = 1 << 2; /* bit 2 of index: ps */
if (root_level == PT32E_ROOT_LEVEL)
--root_level;
/* PT_PAGE_TABLE_LEVEL always terminates */
map = 1 | (1 << ps_set_index);
for (level = PT_DIRECTORY_LEVEL; level <= root_level; ++level) {
if (level <= PT_PDPE_LEVEL
&& (mmu->root_level >= PT32E_ROOT_LEVEL || is_pse(vcpu)))
map |= 1 << (ps_set_index | (level - 1));
}
mmu->last_pte_bitmap = map;
}
static int 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);
update_last_pte_bitmap(vcpu, context);
ASSERT(is_pae(vcpu));
context->new_cr3 = paging_new_cr3;
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->free = paging_free;
context->shadow_root_level = level;
context->root_hpa = INVALID_PAGE;
context->direct_map = false;
return 0;
}
static int paging64_init_context(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
return paging64_init_context_common(vcpu, context, PT64_ROOT_LEVEL);
}
static int 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);
update_last_pte_bitmap(vcpu, context);
context->new_cr3 = paging_new_cr3;
context->page_fault = paging32_page_fault;
context->gva_to_gpa = paging32_gva_to_gpa;
context->free = paging_free;
context->sync_page = paging32_sync_page;
context->invlpg = paging32_invlpg;
context->update_pte = paging32_update_pte;
context->shadow_root_level = PT32E_ROOT_LEVEL;
context->root_hpa = INVALID_PAGE;
context->direct_map = false;
return 0;
}
static int paging32E_init_context(struct kvm_vcpu *vcpu,
struct kvm_mmu *context)
{
return paging64_init_context_common(vcpu, context, PT32E_ROOT_LEVEL);
}
static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = vcpu->arch.walk_mmu;
context->base_role.word = 0;
context->new_cr3 = nonpaging_new_cr3;
context->page_fault = tdp_page_fault;
context->free = nonpaging_free;
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();
context->root_hpa = INVALID_PAGE;
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 = PT64_ROOT_LEVEL;
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);
update_last_pte_bitmap(vcpu, context);
return 0;
}
int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
{
int r;
bool smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
if (!is_paging(vcpu))
r = nonpaging_init_context(vcpu, context);
else if (is_long_mode(vcpu))
r = paging64_init_context(vcpu, context);
else if (is_pae(vcpu))
r = paging32E_init_context(vcpu, context);
else
r = paging32_init_context(vcpu, context);
vcpu->arch.mmu.base_role.nxe = is_nx(vcpu);
vcpu->arch.mmu.base_role.cr4_pae = !!is_pae(vcpu);
vcpu->arch.mmu.base_role.cr0_wp = is_write_protection(vcpu);
vcpu->arch.mmu.base_role.smep_andnot_wp
= smep && !is_write_protection(vcpu);
return r;
}
EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
static int init_kvm_softmmu(struct kvm_vcpu *vcpu)
{
int r = kvm_init_shadow_mmu(vcpu, vcpu->arch.walk_mmu);
vcpu->arch.walk_mmu->set_cr3 = kvm_x86_ops->set_cr3;
vcpu->arch.walk_mmu->get_cr3 = get_cr3;
vcpu->arch.walk_mmu->get_pdptr = kvm_pdptr_read;
vcpu->arch.walk_mmu->inject_page_fault = kvm_inject_page_fault;
return r;
}
static int init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *g_context = &vcpu->arch.nested_mmu;
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_gva to l1_gpa. The
* translation of l2_gpa to l1_gpa addresses is done using the
* arch.nested_mmu.gva_to_gpa function. 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 = PT64_ROOT_LEVEL;
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);
update_last_pte_bitmap(vcpu, g_context);
return 0;
}
static int init_kvm_mmu(struct kvm_vcpu *vcpu)
{
if (mmu_is_nested(vcpu))
return init_kvm_nested_mmu(vcpu);
else if (tdp_enabled)
return init_kvm_tdp_mmu(vcpu);
else
return init_kvm_softmmu(vcpu);
}
static void destroy_kvm_mmu(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
if (VALID_PAGE(vcpu->arch.mmu.root_hpa))
/* mmu.free() should set root_hpa = INVALID_PAGE */
vcpu->arch.mmu.free(vcpu);
}
int kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
{
destroy_kvm_mmu(vcpu);
return init_kvm_mmu(vcpu);
}
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);
spin_lock(&vcpu->kvm->mmu_lock);
mmu_sync_roots(vcpu);
spin_unlock(&vcpu->kvm->mmu_lock);
if (r)
goto out;
/* set_cr3() should ensure TLB has been flushed */
vcpu->arch.mmu.set_cr3(vcpu, vcpu->arch.mmu.root_hpa);
out:
return r;
}
EXPORT_SYMBOL_GPL(kvm_mmu_load);
void kvm_mmu_unload(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
}
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 ^= PT64_NX_MASK;
new ^= PT64_NX_MASK;
return (old & ~new & PT64_PERM_MASK) != 0;
}
static void mmu_pte_write_flush_tlb(struct kvm_vcpu *vcpu, bool zap_page,
bool remote_flush, bool local_flush)
{
if (zap_page)
return;
if (remote_flush)
kvm_flush_remote_tlbs(vcpu->kvm);
else if (local_flush)
kvm_mmu_flush_tlb(vcpu);
}
static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa,
const u8 *new, int *bytes)
{
u64 gentry;
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;
r = kvm_read_guest(vcpu->kvm, *gpa, &gentry, 8);
if (r)
gentry = 0;
new = (const u8 *)&gentry;
}
switch (*bytes) {
case 4:
gentry = *(const u32 *)new;
break;
case 8:
gentry = *(const u64 *)new;
break;
default:
gentry = 0;
break;
}
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;
return ++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;
}
void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
union kvm_mmu_page_role mask = { .word = 0 };
struct kvm_mmu_page *sp;
LIST_HEAD(invalid_list);
u64 entry, gentry, *spte;
int npte;
bool remote_flush, local_flush, zap_page;
/*
* If we don't have indirect shadow pages, it means no page is
* write-protected, so we can exit simply.
*/
if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages))
return;
zap_page = remote_flush = local_flush = false;
pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);
gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, new, &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);
++vcpu->kvm->stat.mmu_pte_write;
kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);
mask.cr0_wp = mask.cr4_pae = mask.nxe = 1;
for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) {
if (detect_write_misaligned(sp, gpa, bytes) ||
detect_write_flooding(sp)) {
zap_page |= !!kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
&invalid_list);
++vcpu->kvm->stat.mmu_flooded;
continue;
}
spte = get_written_sptes(sp, gpa, &npte);
if (!spte)
continue;
local_flush = true;
while (npte--) {
entry = *spte;
mmu_page_zap_pte(vcpu->kvm, sp, spte);
if (gentry &&
!((sp->role.word ^ vcpu->arch.mmu.base_role.word)
& 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;
}
}
mmu_pte_write_flush_tlb(vcpu, zap_page, remote_flush, local_flush);
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
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 void 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;
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);
}
static bool is_mmio_page_fault(struct kvm_vcpu *vcpu, gva_t addr)
{
if (vcpu->arch.mmu.direct_map || mmu_is_nested(vcpu))
return vcpu_match_mmio_gpa(vcpu, addr);
return vcpu_match_mmio_gva(vcpu, addr);
}
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code,
void *insn, int insn_len)
{
int r, emulation_type = EMULTYPE_RETRY;
enum emulation_result er;
r = vcpu->arch.mmu.page_fault(vcpu, cr2, error_code, false);
if (r < 0)
goto out;
if (!r) {
r = 1;
goto out;
}
if (is_mmio_page_fault(vcpu, cr2))
emulation_type = 0;
er = x86_emulate_instruction(vcpu, cr2, emulation_type, insn, insn_len);
switch (er) {
case EMULATE_DONE:
return 1;
case EMULATE_DO_MMIO:
++vcpu->stat.mmio_exits;
/* fall through */
case EMULATE_FAIL:
return 0;
default:
BUG();
}
out:
return r;
}
EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);
void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva)
{
vcpu->arch.mmu.invlpg(vcpu, gva);
kvm_mmu_flush_tlb(vcpu);
++vcpu->stat.invlpg;
}
EXPORT_SYMBOL_GPL(kvm_mmu_invlpg);
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);
if (vcpu->arch.mmu.lm_root != NULL)
free_page((unsigned long)vcpu->arch.mmu.lm_root);
}
static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
{
struct page *page;
int i;
ASSERT(vcpu);
/*
* 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)
{
ASSERT(vcpu);
vcpu->arch.walk_mmu = &vcpu->arch.mmu;
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
vcpu->arch.mmu.translate_gpa = translate_gpa;
vcpu->arch.nested_mmu.translate_gpa = translate_nested_gpa;
return alloc_mmu_pages(vcpu);
}
int kvm_mmu_setup(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
return init_kvm_mmu(vcpu);
}
void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
{
struct kvm_memory_slot *memslot;
gfn_t last_gfn;
int i;
memslot = id_to_memslot(kvm->memslots, slot);
last_gfn = memslot->base_gfn + memslot->npages - 1;
spin_lock(&kvm->mmu_lock);
for (i = PT_PAGE_TABLE_LEVEL;
i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
unsigned long *rmapp;
unsigned long last_index, index;
rmapp = memslot->arch.rmap[i - PT_PAGE_TABLE_LEVEL];
last_index = gfn_to_index(last_gfn, memslot->base_gfn, i);
for (index = 0; index <= last_index; ++index, ++rmapp) {
if (*rmapp)
__rmap_write_protect(kvm, rmapp, false);
if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
kvm_flush_remote_tlbs(kvm);
cond_resched_lock(&kvm->mmu_lock);
}
}
}
kvm_flush_remote_tlbs(kvm);
spin_unlock(&kvm->mmu_lock);
}
void kvm_mmu_zap_all(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
LIST_HEAD(invalid_list);
spin_lock(&kvm->mmu_lock);
restart:
list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link)
if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list))
goto restart;
kvm_mmu_commit_zap_page(kvm, &invalid_list);
spin_unlock(&kvm->mmu_lock);
}
void kvm_mmu_zap_mmio_sptes(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
LIST_HEAD(invalid_list);
spin_lock(&kvm->mmu_lock);
restart:
list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) {
if (!sp->mmio_cached)
continue;
if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list))
goto restart;
}
kvm_mmu_commit_zap_page(kvm, &invalid_list);
spin_unlock(&kvm->mmu_lock);
}
static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
{
struct kvm *kvm;
int nr_to_scan = sc->nr_to_scan;
if (nr_to_scan == 0)
goto out;
raw_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)
continue;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
prepare_zap_oldest_mmu_page(kvm, &invalid_list);
kvm_mmu_commit_zap_page(kvm, &invalid_list);
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
list_move_tail(&kvm->vm_list, &vm_list);
break;
}
raw_spin_unlock(&kvm_lock);
out:
return percpu_counter_read_positive(&kvm_total_used_mmu_pages);
}
static struct shrinker mmu_shrinker = {
.shrink = mmu_shrink,
.seeks = DEFAULT_SEEKS * 10,
};
static void mmu_destroy_caches(void)
{
if (pte_list_desc_cache)
kmem_cache_destroy(pte_list_desc_cache);
if (mmu_page_header_cache)
kmem_cache_destroy(mmu_page_header_cache);
}
int kvm_mmu_module_init(void)
{
pte_list_desc_cache = kmem_cache_create("pte_list_desc",
sizeof(struct pte_list_desc),
0, 0, NULL);
if (!pte_list_desc_cache)
goto nomem;
mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header",
sizeof(struct kvm_mmu_page),
0, 0, NULL);
if (!mmu_page_header_cache)
goto nomem;
if (percpu_counter_init(&kvm_total_used_mmu_pages, 0))
goto nomem;
register_shrinker(&mmu_shrinker);
return 0;
nomem:
mmu_destroy_caches();
return -ENOMEM;
}
/*
* Caculate 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;
slots = kvm_memslots(kvm);
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;
}
int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4])
{
struct kvm_shadow_walk_iterator iterator;
u64 spte;
int nr_sptes = 0;
walk_shadow_page_lockless_begin(vcpu);
for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) {
sptes[iterator.level-1] = spte;
nr_sptes++;
if (!is_shadow_present_pte(spte))
break;
}
walk_shadow_page_lockless_end(vcpu);
return nr_sptes;
}
EXPORT_SYMBOL_GPL(kvm_mmu_get_spte_hierarchy);
void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
destroy_kvm_mmu(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();
}