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KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range 

This together with previous patch, ensures that
kvm_zap_gfn_range doesn't race with page fault
running on another vcpu, and will make this page fault code
retry instead.

This is based on a patch suggested by Sean Christopherson:
https://lkml.org/lkml/2021/7/22/1025

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210810205251.424103-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Maxim Levitsky 2021-08-10 23:52:39 +03:00 committed by Paolo Bonzini
parent 88f585358b
commit edb298c663
3 changed files with 14 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/kvm/mmu/mmu.c
View File

@ -5688,6 +5688,8 @@ 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);
if (kvm_memslots_have_rmaps(kvm)) {
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
slots = __kvm_memslots(kvm, i);
@ -5723,6 +5725,8 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
if (flush)
kvm_flush_remote_tlbs_with_address(kvm, gfn_start, gfn_end);
kvm_dec_notifier_count(kvm, gfn_start, gfn_end);
write_unlock(&kvm->mmu_lock);
}

5
include/linux/kvm_host.h
View File

@ -991,6 +991,11 @@ 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);
long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
long kvm_arch_vcpu_ioctl(struct file *filp,

7
virt/kvm/kvm_main.c
View File

@ -610,7 +610,7 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);
}
static void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
unsigned long end)
{
/*
@ -638,6 +638,7 @@ static void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
max(kvm->mmu_notifier_range_end, end);
}
}
EXPORT_SYMBOL_GPL(kvm_inc_notifier_count);
static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
const struct mmu_notifier_range *range)
@ -672,7 +673,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
return 0;
}
static void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
unsigned long end)
{
/*
@ -689,6 +690,8 @@ static void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
*/
kvm->mmu_notifier_count--;
}
EXPORT_SYMBOL_GPL(kvm_dec_notifier_count);
static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
const struct mmu_notifier_range *range)