Commit f1c4a88c authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Paolo Bonzini
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KVM: X86: Don't unsync pagetables when speculative 



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

Signed-off-by: default avatarLai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210918005636.3675-10-jiangshanlai@gmail.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent cc2a8e66

arch/x86/kvm/mmu/mmu.c

+5 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/kvm/mmu/mmu_internal.h

+2 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/mmu/spte.c

+1 −1
Original line number Diff line number Diff line
@@ -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;