[PATCH v3 05/11] KVM: MMU: do not mark accessed bit on pte write path

Xiao Guangrong
2011-08-30T02:34:00Z

In current code, the accessed bit is always set when page fault occurred,
do not need to set it on pte write path

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/include/asm/kvm_host.h | 1 -
arch/x86/kvm/mmu.c | 22 +---------------------
2 files changed, 1 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 27a25df..58ea3a7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -356,7 +356,6 @@ struct kvm_vcpu_arch {
gfn_t last_pt_write_gfn;
int last_pt_write_count;
u64 *last_pte_updated;
- gfn_t last_pte_gfn;

struct fpu guest_fpu;
u64 xcr0;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 26aae11..7ec2a6a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2206,11 +2206,6 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
if (set_mmio_spte(sptep, gfn, pfn, pte_access))
return 0;

- /*
- * We don't set the accessed bit, since we sometimes want to see
- * whether the guest actually used the pte (in order to detect
- * demand paging).
- */
spte = PT_PRESENT_MASK;
if (!speculative)
spte |= shadow_accessed_mask;
@@ -2361,10 +2356,8 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
}
}
kvm_release_pfn_clean(pfn);
- if (speculative) {
+ if (speculative)
vcpu->arch.last_pte_updated = sptep;
- vcpu->arch.last_pte_gfn = gfn;
- }
}

static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
@@ -3532,18 +3525,6 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu)
return !!(spte && (*spte & shadow_accessed_mask));
}

-static void kvm_mmu_access_page(struct kvm_vcpu *vcpu, gfn_t gfn)
-{
- u64 *spte = vcpu->arch.last_pte_updated;
-
- if (spte
- && vcpu->arch.last_pte_gfn == gfn
- && shadow_accessed_mask
- && !(*spte & shadow_accessed_mask)
- && is_shadow_present_pte(*spte))
- set_bit(PT_ACCESSED_SHIFT, (unsigned long *)spte);
-}
-
void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes,
bool guest_initiated)
@@ -3614,7 +3595,6 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
++vcpu->kvm->stat.mmu_pte_write;
trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE);
if (guest_initiated) {
- kvm_mmu_access_page(vcpu, gfn);
if (gfn == vcpu->arch.last_pt_write_gfn
&& !last_updated_pte_accessed(vcpu)) {
++vcpu->arch.last_pt_write_count;
--
1.7.5.4