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KVM: Rename mmu_notifier_* to mmu_invalidate_*

Browse Source 
The motivation of this renaming is to make these variables and related
helper functions less mmu_notifier bound and can also be used for non
mmu_notifier based page invalidation. mmu_invalidate_* was chosen to
better describe the purpose of 'invalidating' a page that those
variables are used for.

  - mmu_notifier_seq/range_start/range_end are renamed to
    mmu_invalidate_seq/range_start/range_end.

  - mmu_notifier_retry{_hva} helper functions are renamed to
    mmu_invalidate_retry{_hva}.

  - mmu_notifier_count is renamed to mmu_invalidate_in_progress to
    avoid confusion with mn_active_invalidate_count.

  - While here, also update kvm_inc/dec_notifier_count() to
    kvm_mmu_invalidate_begin/end() to match the change for
    mmu_notifier_count.

No functional change intended.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Message-Id: <20220816125322.1110439-3-chao.p.peng@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Chao Peng 2022-08-16 20:53:22 +08:00 committed by Paolo Bonzini
parent bdd1c37a31
commit 20ec3ebd70
15 changed files with 103 additions and 98 deletions
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8
arch/arm64/kvm/mmu.c
View File

@ -993,7 +993,7 @@ transparent_hugepage_adjust(struct kvm *kvm, struct kvm_memory_slot *memslot,
* THP doesn't start to split while we are adjusting the
* refcounts.
*
* We are sure this doesn't happen, because mmu_notifier_retry
* We are sure this doesn't happen, because mmu_invalidate_retry
* was successful and we are holding the mmu_lock, so if this
* THP is trying to split, it will be blocked in the mmu
* notifier before touching any of the pages, specifically
@ -1188,9 +1188,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
return ret;
}
mmu_seq = vcpu->kvm->mmu_notifier_seq;
mmu_seq = vcpu->kvm->mmu_invalidate_seq;
/*
* Ensure the read of mmu_notifier_seq happens before we call
* Ensure the read of mmu_invalidate_seq happens before we call
* gfn_to_pfn_prot (which calls get_user_pages), so that we don't risk
* the page we just got a reference to gets unmapped before we have a
* chance to grab the mmu_lock, which ensure that if the page gets
@ -1246,7 +1246,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
else
write_lock(&kvm->mmu_lock);
pgt = vcpu->arch.hw_mmu->pgt;
if (mmu_notifier_retry(kvm, mmu_seq))
if (mmu_invalidate_retry(kvm, mmu_seq))
goto out_unlock;
/*

12
arch/mips/kvm/mmu.c
View File

@ -615,17 +615,17 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa,
* Used to check for invalidations in progress, of the pfn that is
* returned by pfn_to_pfn_prot below.
*/
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
/*
* Ensure the read of mmu_notifier_seq isn't reordered with PTE reads in
* gfn_to_pfn_prot() (which calls get_user_pages()), so that we don't
* Ensure the read of mmu_invalidate_seq isn't reordered with PTE reads
* in gfn_to_pfn_prot() (which calls get_user_pages()), so that we don't
* risk the page we get a reference to getting unmapped before we have a
* chance to grab the mmu_lock without mmu_notifier_retry() noticing.
* chance to grab the mmu_lock without mmu_invalidate_retry() noticing.
*
* This smp_rmb() pairs with the effective smp_wmb() of the combination
* of the pte_unmap_unlock() after the PTE is zapped, and the
* spin_lock() in kvm_mmu_notifier_invalidate_<page|range_end>() before
* mmu_notifier_seq is incremented.
* mmu_invalidate_seq is incremented.
*/
smp_rmb();
@ -638,7 +638,7 @@ static int kvm_mips_map_page(struct kvm_vcpu *vcpu, unsigned long gpa,
spin_lock(&kvm->mmu_lock);
/* Check if an invalidation has taken place since we got pfn */
if (mmu_notifier_retry(kvm, mmu_seq)) {
if (mmu_invalidate_retry(kvm, mmu_seq)) {
/*
* This can happen when mappings are changed asynchronously, but
* also synchronously if a COW is triggered by

2
arch/powerpc/include/asm/kvm_book3s_64.h
View File

@ -666,7 +666,7 @@ static inline pte_t *find_kvm_host_pte(struct kvm *kvm, unsigned long mmu_seq,
VM_WARN(!spin_is_locked(&kvm->mmu_lock),
"%s called with kvm mmu_lock not held \n", __func__);
if (mmu_notifier_retry(kvm, mmu_seq))
if (mmu_invalidate_retry(kvm, mmu_seq))
return NULL;
pte = __find_linux_pte(kvm->mm->pgd, ea, NULL, hshift);

4
arch/powerpc/kvm/book3s_64_mmu_host.c
View File

@ -90,7 +90,7 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte,
unsigned long pfn;
/* used to check for invalidations in progress */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
/* Get host physical address for gpa */
@ -151,7 +151,7 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte,
cpte = kvmppc_mmu_hpte_cache_next(vcpu);
spin_lock(&kvm->mmu_lock);
if (!cpte || mmu_notifier_retry(kvm, mmu_seq)) {
if (!cpte || mmu_invalidate_retry(kvm, mmu_seq)) {
r = -EAGAIN;
goto out_unlock;
}

4
arch/powerpc/kvm/book3s_64_mmu_hv.c
View File

@ -578,7 +578,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu,
return -EFAULT;
/* used to check for invalidations in progress */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
ret = -EFAULT;
@ -693,7 +693,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu,
/* Check if we might have been invalidated; let the guest retry if so */
ret = RESUME_GUEST;
if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) {
if (mmu_invalidate_retry(vcpu->kvm, mmu_seq)) {
unlock_rmap(rmap);
goto out_unlock;
}

6
arch/powerpc/kvm/book3s_64_mmu_radix.c
View File

@ -640,7 +640,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
/* Check if we might have been invalidated; let the guest retry if so */
spin_lock(&kvm->mmu_lock);
ret = -EAGAIN;
if (mmu_notifier_retry(kvm, mmu_seq))
if (mmu_invalidate_retry(kvm, mmu_seq))
goto out_unlock;
/* Now traverse again under the lock and change the tree */
@ -830,7 +830,7 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
bool large_enable;
/* used to check for invalidations in progress */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
/*
@ -1191,7 +1191,7 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm,
* Increase the mmu notifier sequence number to prevent any page
* fault that read the memslot earlier from writing a PTE.
*/
kvm->mmu_notifier_seq++;
kvm->mmu_invalidate_seq++;
spin_unlock(&kvm->mmu_lock);
}

2
arch/powerpc/kvm/book3s_hv_nested.c
View File

@ -1580,7 +1580,7 @@ static long int __kvmhv_nested_page_fault(struct kvm_vcpu *vcpu,
/* 2. Find the host pte for this L1 guest real address */
/* Used to check for invalidations in progress */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
/* See if can find translation in our partition scoped tables for L1 */

8
arch/powerpc/kvm/book3s_hv_rm_mmu.c
View File

@ -219,7 +219,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
g_ptel = ptel;
/* used later to detect if we might have been invalidated */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
/* Find the memslot (if any) for this address */
@ -366,7 +366,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
rmap = real_vmalloc_addr(rmap);
lock_rmap(rmap);
/* Check for pending invalidations under the rmap chain lock */
if (mmu_notifier_retry(kvm, mmu_seq)) {
if (mmu_invalidate_retry(kvm, mmu_seq)) {
/* inval in progress, write a non-present HPTE */
pteh |= HPTE_V_ABSENT;
pteh &= ~HPTE_V_VALID;
@ -932,7 +932,7 @@ static long kvmppc_do_h_page_init_zero(struct kvm_vcpu *vcpu,
int i;
/* Used later to detect if we might have been invalidated */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock);
@ -960,7 +960,7 @@ static long kvmppc_do_h_page_init_copy(struct kvm_vcpu *vcpu,
long ret = H_SUCCESS;
/* Used later to detect if we might have been invalidated */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock);

4
arch/powerpc/kvm/e500_mmu_host.c
View File

@ -339,7 +339,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
unsigned long flags;
/* used to check for invalidations in progress */
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
/*
@ -460,7 +460,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
}
spin_lock(&kvm->mmu_lock);
if (mmu_notifier_retry(kvm, mmu_seq)) {
if (mmu_invalidate_retry(kvm, mmu_seq)) {
ret = -EAGAIN;
goto out;
}

4
arch/riscv/kvm/mmu.c
View File

@ -666,7 +666,7 @@ int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
return ret;
}
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
hfn = gfn_to_pfn_prot(kvm, gfn, is_write, &writable);
if (hfn == KVM_PFN_ERR_HWPOISON) {
@ -686,7 +686,7 @@ int kvm_riscv_gstage_map(struct kvm_vcpu *vcpu,
spin_lock(&kvm->mmu_lock);
if (mmu_notifier_retry(kvm, mmu_seq))
if (mmu_invalidate_retry(kvm, mmu_seq))
goto out_unlock;
if (writable) {

14
arch/x86/kvm/mmu/mmu.c
View File

@ -2914,7 +2914,7 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
* If addresses are being invalidated, skip prefetching to avoid
* accidentally prefetching those addresses.
*/
if (unlikely(vcpu->kvm->mmu_notifier_count))
if (unlikely(vcpu->kvm->mmu_invalidate_in_progress))
return;
__direct_pte_prefetch(vcpu, sp, sptep);
@ -2928,7 +2928,7 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
*
* There are several ways to safely use this helper:
*
* - Check mmu_notifier_retry_hva() after grabbing the mapping level, before
* - Check mmu_invalidate_retry_hva() after grabbing the mapping level, before
* consuming it. In this case, mmu_lock doesn't need to be held during the
* lookup, but it does need to be held while checking the MMU notifier.
*
@ -3056,7 +3056,7 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
return;
/*
* mmu_notifier_retry() was successful and mmu_lock is held, so
* mmu_invalidate_retry() was successful and mmu_lock is held, so
* the pmd can't be split from under us.
*/
fault->goal_level = fault->req_level;
@ -4203,7 +4203,7 @@ static bool is_page_fault_stale(struct kvm_vcpu *vcpu,
return true;
return fault->slot &&
mmu_notifier_retry_hva(vcpu->kvm, mmu_seq, fault->hva);
mmu_invalidate_retry_hva(vcpu->kvm, mmu_seq, fault->hva);
}
static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
@ -4227,7 +4227,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
if (r)
return r;
mmu_seq = vcpu->kvm->mmu_notifier_seq;
mmu_seq = vcpu->kvm->mmu_invalidate_seq;
smp_rmb();
r = kvm_faultin_pfn(vcpu, fault);
@ -6055,7 +6055,7 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
write_lock(&kvm->mmu_lock);
kvm_inc_notifier_count(kvm, gfn_start, gfn_end);
kvm_mmu_invalidate_begin(kvm, gfn_start, gfn_end);
flush = kvm_rmap_zap_gfn_range(kvm, gfn_start, gfn_end);
@ -6069,7 +6069,7 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
kvm_flush_remote_tlbs_with_address(kvm, gfn_start,
gfn_end - gfn_start);
kvm_dec_notifier_count(kvm, gfn_start, gfn_end);
kvm_mmu_invalidate_end(kvm, gfn_start, gfn_end);
write_unlock(&kvm->mmu_lock);
}

4
arch/x86/kvm/mmu/paging_tmpl.h
View File

@ -589,7 +589,7 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
* If addresses are being invalidated, skip prefetching to avoid
* accidentally prefetching those addresses.
*/
if (unlikely(vcpu->kvm->mmu_notifier_count))
if (unlikely(vcpu->kvm->mmu_invalidate_in_progress))
return;
if (sp->role.direct)
@ -838,7 +838,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
else
fault->max_level = walker.level;
mmu_seq = vcpu->kvm->mmu_notifier_seq;
mmu_seq = vcpu->kvm->mmu_invalidate_seq;
smp_rmb();
r = kvm_faultin_pfn(vcpu, fault);

60
include/linux/kvm_host.h
View File

@ -765,10 +765,10 @@ struct kvm {
#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
struct mmu_notifier mmu_notifier;
unsigned long mmu_notifier_seq;
long mmu_notifier_count;
unsigned long mmu_notifier_range_start;
unsigned long mmu_notifier_range_end;
unsigned long mmu_invalidate_seq;
long mmu_invalidate_in_progress;
unsigned long mmu_invalidate_range_start;
unsigned long mmu_invalidate_range_end;
#endif
struct list_head devices;
u64 manual_dirty_log_protect;
@ -1357,10 +1357,10 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc);
void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
#endif
void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
unsigned long end);
void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
unsigned long end);
void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start,
unsigned long end);
void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start,
unsigned long end);
long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
@ -1907,42 +1907,44 @@ extern const struct kvm_stats_header kvm_vcpu_stats_header;
extern const struct _kvm_stats_desc kvm_vcpu_stats_desc[];
#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
static inline int mmu_invalidate_retry(struct kvm *kvm, unsigned long mmu_seq)
{
if (unlikely(kvm->mmu_notifier_count))
if (unlikely(kvm->mmu_invalidate_in_progress))
return 1;
/*
* Ensure the read of mmu_notifier_count happens before the read
* of mmu_notifier_seq. This interacts with the smp_wmb() in
* mmu_notifier_invalidate_range_end to make sure that the caller
* either sees the old (non-zero) value of mmu_notifier_count or
* the new (incremented) value of mmu_notifier_seq.
* PowerPC Book3s HV KVM calls this under a per-page lock
* rather than under kvm->mmu_lock, for scalability, so
* can't rely on kvm->mmu_lock to keep things ordered.
* Ensure the read of mmu_invalidate_in_progress happens before
* the read of mmu_invalidate_seq. This interacts with the
* smp_wmb() in mmu_notifier_invalidate_range_end to make sure
* that the caller either sees the old (non-zero) value of
* mmu_invalidate_in_progress or the new (incremented) value of
* mmu_invalidate_seq.
*
* PowerPC Book3s HV KVM calls this under a per-page lock rather
* than under kvm->mmu_lock, for scalability, so can't rely on
* kvm->mmu_lock to keep things ordered.
*/
smp_rmb();
if (kvm->mmu_notifier_seq != mmu_seq)
if (kvm->mmu_invalidate_seq != mmu_seq)
return 1;
return 0;
}
static inline int mmu_notifier_retry_hva(struct kvm *kvm,
unsigned long mmu_seq,
unsigned long hva)
static inline int mmu_invalidate_retry_hva(struct kvm *kvm,
unsigned long mmu_seq,
unsigned long hva)
{
lockdep_assert_held(&kvm->mmu_lock);
/*
* If mmu_notifier_count is non-zero, then the range maintained by
* kvm_mmu_notifier_invalidate_range_start contains all addresses that
* might be being invalidated. Note that it may include some false
* If mmu_invalidate_in_progress is non-zero, then the range maintained
* by kvm_mmu_notifier_invalidate_range_start contains all addresses
* that might be being invalidated. Note that it may include some false
* positives, due to shortcuts when handing concurrent invalidations.
*/
if (unlikely(kvm->mmu_notifier_count) &&
hva >= kvm->mmu_notifier_range_start &&
hva < kvm->mmu_notifier_range_end)
if (unlikely(kvm->mmu_invalidate_in_progress) &&
hva >= kvm->mmu_invalidate_range_start &&
hva < kvm->mmu_invalidate_range_end)
return 1;
if (kvm->mmu_notifier_seq != mmu_seq)
if (kvm->mmu_invalidate_seq != mmu_seq)
return 1;
return 0;
}

52
virt/kvm/kvm_main.c
View File

@ -702,30 +702,31 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
/*
* .change_pte() must be surrounded by .invalidate_range_{start,end}().
* If mmu_notifier_count is zero, then no in-progress invalidations,
* including this one, found a relevant memslot at start(); rechecking
* memslots here is unnecessary. Note, a false positive (count elevated
* by a different invalidation) is sub-optimal but functionally ok.
* If mmu_invalidate_in_progress is zero, then no in-progress
* invalidations, including this one, found a relevant memslot at
* start(); rechecking memslots here is unnecessary. Note, a false
* positive (count elevated by a different invalidation) is sub-optimal
* but functionally ok.
*/
WARN_ON_ONCE(!READ_ONCE(kvm->mn_active_invalidate_count));
if (!READ_ONCE(kvm->mmu_notifier_count))
if (!READ_ONCE(kvm->mmu_invalidate_in_progress))
return;
kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);
}
void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
unsigned long end)
void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start,
unsigned long end)
{
/*
* The count increase must become visible at unlock time as no
* spte can be established without taking the mmu_lock and
* count is also read inside the mmu_lock critical section.
*/
kvm->mmu_notifier_count++;
if (likely(kvm->mmu_notifier_count == 1)) {
kvm->mmu_notifier_range_start = start;
kvm->mmu_notifier_range_end = end;
kvm->mmu_invalidate_in_progress++;
if (likely(kvm->mmu_invalidate_in_progress == 1)) {
kvm->mmu_invalidate_range_start = start;
kvm->mmu_invalidate_range_end = end;
} else {
/*
* Fully tracking multiple concurrent ranges has diminishing
@ -736,10 +737,10 @@ void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
* accumulate and persist until all outstanding invalidates
* complete.
*/
kvm->mmu_notifier_range_start =
min(kvm->mmu_notifier_range_start, start);
kvm->mmu_notifier_range_end =
max(kvm->mmu_notifier_range_end, end);
kvm->mmu_invalidate_range_start =
min(kvm->mmu_invalidate_range_start, start);
kvm->mmu_invalidate_range_end =
max(kvm->mmu_invalidate_range_end, end);
}
}
@ -752,7 +753,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
.end = range->end,
.pte = __pte(0),
.handler = kvm_unmap_gfn_range,
.on_lock = kvm_inc_notifier_count,
.on_lock = kvm_mmu_invalidate_begin,
.on_unlock = kvm_arch_guest_memory_reclaimed,
.flush_on_ret = true,
.may_block = mmu_notifier_range_blockable(range),
@ -763,7 +764,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
/*
* Prevent memslot modification between range_start() and range_end()
* so that conditionally locking provides the same result in both
* functions. Without that guarantee, the mmu_notifier_count
* functions. Without that guarantee, the mmu_invalidate_in_progress
* adjustments will be imbalanced.
*
* Pairs with the decrement in range_end().
@ -779,7 +780,8 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
* any given time, and the caches themselves can check for hva overlap,
* i.e. don't need to rely on memslot overlap checks for performance.
* Because this runs without holding mmu_lock, the pfn caches must use
* mn_active_invalidate_count (see above) instead of mmu_notifier_count.
* mn_active_invalidate_count (see above) instead of
* mmu_invalidate_in_progress.
*/
gfn_to_pfn_cache_invalidate_start(kvm, range->start, range->end,
hva_range.may_block);
@ -789,22 +791,22 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
return 0;
}
void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
unsigned long end)
void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start,
unsigned long end)
{
/*
* This sequence increase will notify the kvm page fault that
* the page that is going to be mapped in the spte could have
* been freed.
*/
kvm->mmu_notifier_seq++;
kvm->mmu_invalidate_seq++;
smp_wmb();
/*
* The above sequence increase must be visible before the
* below count decrease, which is ensured by the smp_wmb above
* in conjunction with the smp_rmb in mmu_notifier_retry().
* in conjunction with the smp_rmb in mmu_invalidate_retry().
*/
kvm->mmu_notifier_count--;
kvm->mmu_invalidate_in_progress--;
}
static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
@ -816,7 +818,7 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
.end = range->end,
.pte = __pte(0),
.handler = (void *)kvm_null_fn,
.on_lock = kvm_dec_notifier_count,
.on_lock = kvm_mmu_invalidate_end,
.on_unlock = (void *)kvm_null_fn,
.flush_on_ret = false,
.may_block = mmu_notifier_range_blockable(range),
@ -837,7 +839,7 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
if (wake)
rcuwait_wake_up(&kvm->mn_memslots_update_rcuwait);
BUG_ON(kvm->mmu_notifier_count < 0);
BUG_ON(kvm->mmu_invalidate_in_progress < 0);
}
static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,

17
virt/kvm/pfncache.c
View File

@ -112,27 +112,28 @@ static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_s
{
/*
* mn_active_invalidate_count acts for all intents and purposes
* like mmu_notifier_count here; but the latter cannot be used
* here because the invalidation of caches in the mmu_notifier
* event occurs _before_ mmu_notifier_count is elevated.
* like mmu_invalidate_in_progress here; but the latter cannot
* be used here because the invalidation of caches in the
* mmu_notifier event occurs _before_ mmu_invalidate_in_progress
* is elevated.
*
* Note, it does not matter that mn_active_invalidate_count
* is not protected by gpc->lock. It is guaranteed to
* be elevated before the mmu_notifier acquires gpc->lock, and
* isn't dropped until after mmu_notifier_seq is updated.
* isn't dropped until after mmu_invalidate_seq is updated.
*/
if (kvm->mn_active_invalidate_count)
return true;
/*
* Ensure mn_active_invalidate_count is read before
* mmu_notifier_seq. This pairs with the smp_wmb() in
* mmu_invalidate_seq. This pairs with the smp_wmb() in
* mmu_notifier_invalidate_range_end() to guarantee either the
* old (non-zero) value of mn_active_invalidate_count or the
* new (incremented) value of mmu_notifier_seq is observed.
* new (incremented) value of mmu_invalidate_seq is observed.
*/
smp_rmb();
return kvm->mmu_notifier_seq != mmu_seq;
return kvm->mmu_invalidate_seq != mmu_seq;
}
static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, struct gfn_to_pfn_cache *gpc)
@ -155,7 +156,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, struct gfn_to_pfn_cache *gpc)
gpc->valid = false;
do {
mmu_seq = kvm->mmu_notifier_seq;
mmu_seq = kvm->mmu_invalidate_seq;
smp_rmb();
write_unlock_irq(&gpc->lock);