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

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

Signed-off-by: Lai 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: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Lai Jiangshan
2023-02-17 07:53:21 +08:00
committed by Sean Christopherson
parent 91ca7672dc
commit 19ace7d6ca
2 changed files with 11 additions and 3 deletions
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12
arch/x86/kvm/mmu/mmu.c
View File

@@ -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);

2
arch/x86/kvm/mmu/paging_tmpl.h
View File

@@ -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);