Commit 19ace7d6 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Sean Christopherson
Browse files

KVM: x86/mmu: Skip calling mmu->sync_spte() when the spte is 0 



Sync the spte only when the spte is set and avoid the indirect branch.

Signed-off-by: default avatarLai Jiangshan <jiangshan.ljs@antgroup.com>
Link: https://lore.kernel.org/r/20230216235321.735214-5-jiangshanlai@gmail.com


[sean: add wrapper instead of open coding each check]
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 91ca7672

arch/x86/kvm/mmu/mmu.c

+10 −2
Original line number Diff line number Diff line
@@ -1933,6 +1933,14 @@ static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 
	return true;

}



static int kvm_sync_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i)

{

	if (!sp->spt[i])

		return 0;



	return vcpu->arch.mmu->sync_spte(vcpu, sp, i);

}



static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)

{

	int flush = 0;
@@ -1942,7 +1950,7 @@ static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 
		return -1;



	for (i = 0; i < SPTE_ENT_PER_PAGE; i++) {

		int ret = vcpu->arch.mmu->sync_spte(vcpu, sp, i);

		int ret = kvm_sync_spte(vcpu, sp, i);



		if (ret < -1)

			return -1;
@@ -5766,7 +5774,7 @@ static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu 
		struct kvm_mmu_page *sp = sptep_to_sp(iterator.sptep);



		if (sp->unsync) {

			int ret = mmu->sync_spte(vcpu, sp, iterator.index);

			int ret = kvm_sync_spte(vcpu, sp, iterator.index);



			if (ret < 0)

				mmu_page_zap_pte(vcpu->kvm, sp, iterator.sptep, NULL);

arch/x86/kvm/mmu/paging_tmpl.h

+1 −1
Original line number Diff line number Diff line
@@ -892,7 +892,7 @@ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int 
	gpa_t pte_gpa;

	gfn_t gfn;



	if (!sp->spt[i])

	if (WARN_ON_ONCE(!sp->spt[i]))

		return 0;



	first_pte_gpa = FNAME(get_level1_sp_gpa)(sp);