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KVM: X86: Don't unsync pagetables when speculative

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We'd better only unsync the pagetable when there just was a really
write fault on a level-1 pagetable.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210918005636.3675-10-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Lai Jiangshan 2021-09-18 08:56:35 +08:00 committed by Paolo Bonzini
parent cc2a8e66bb
commit f1c4a88c41
3 changed files with 8 additions and 3 deletions
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6
arch/x86/kvm/mmu/mmu.c
View File

@ -2582,7 +2582,8 @@ static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
* were marked unsync (or if there is no shadow page), -EPERM if the SPTE must
* be write-protected.
*/
int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync)
int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync,
bool speculative)
{
struct kvm_mmu_page *sp;
bool locked = false;
@ -2608,6 +2609,9 @@ int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync)
if (sp->unsync)
continue;
if (speculative)
return -EEXIST;
/*
* TDP MMU page faults require an additional spinlock as they
* run with mmu_lock held for read, not write, and the unsync

3
arch/x86/kvm/mmu/mmu_internal.h
View File

@ -124,7 +124,8 @@ static inline bool is_nx_huge_page_enabled(void)
return READ_ONCE(nx_huge_pages);
}
int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync);
int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync,
bool speculative);
void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);

2
arch/x86/kvm/mmu/spte.c
View File

@ -159,7 +159,7 @@ int make_spte(struct kvm_vcpu *vcpu, unsigned int pte_access, int level,
* e.g. it's write-tracked (upper-level SPs) or has one or more
* shadow pages and unsync'ing pages is not allowed.
*/
if (mmu_try_to_unsync_pages(vcpu, gfn, can_unsync)) {
if (mmu_try_to_unsync_pages(vcpu, gfn, can_unsync, speculative)) {
pgprintk("%s: found shadow page for %llx, marking ro\n",
__func__, gfn);
ret |= SET_SPTE_WRITE_PROTECTED_PT;