From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
Sync the spte only when the spte is set and avoid the indirect branch.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 4 ++--
arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a8ac37d51287..cd8c38463c97 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1942,7 +1942,7 @@ 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 = sp->spt[i] ? vcpu->arch.mmu->sync_spte(vcpu, sp, i) : 0;
if (ret < -1)
return -1;
@@ -5764,7 +5764,7 @@ static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu
for_each_shadow_entry_using_root(vcpu, root_hpa, addr, iterator) {
struct kvm_mmu_page *sp = sptep_to_sp(iterator.sptep);
- if (sp->unsync) {
+ if (sp->unsync && *iterator.sptep) {
/*
* Get the gfn beforehand for later flushing.
* Although mmu->sync_spte() doesn't change it, but just
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index e04950015dc4..3373d6705634 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -933,7 +933,7 @@ 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);
--
2.19.1.6.gb485710b
