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Subject[PATCH 5/5] KVM: MMU: reduce remote tlb flush in kvm_mmu_pte_write()
collect remote tlb flush in kvm_mmu_pte_write() path

Have tested with xp/vista64, fedora12 32/64 guests, and it not broken

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 20 ++++++++++++++++----
1 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index be75cba..cbd8d9c 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2629,11 +2629,15 @@ static bool need_remote_flush(u64 old, u64 new)
return (old & ~new & PT64_PERM_MASK) != 0;
}

-static void mmu_pte_write_flush_tlb(struct kvm_vcpu *vcpu, u64 old, u64 new)
+static void mmu_pte_write_flush_tlb(struct kvm_vcpu *vcpu, bool zap_page,
+ bool remote_flush, bool local_flush)
{
- if (need_remote_flush(old, new))
+ if (zap_page)
+ return;
+
+ if (remote_flush)
kvm_flush_remote_tlbs(vcpu->kvm);
- else
+ else if (local_flush)
kvm_mmu_flush_tlb(vcpu);
}

@@ -2697,6 +2701,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
int npte;
int r;
int invlpg_counter;
+ bool remote_flush, local_flush, zap_page;
+
+ zap_page = remote_flush = local_flush = false;

pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);

@@ -2770,6 +2777,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
*/
pgprintk("misaligned: gpa %llx bytes %d role %x\n",
gpa, bytes, sp->role.word);
+ zap_page = true;
kvm_mmu_prepare_zap_page(vcpu->kvm, sp);
++vcpu->kvm->stat.mmu_flooded;
continue;
@@ -2794,16 +2802,20 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
if (quadrant != sp->role.quadrant)
continue;
}
+
+ local_flush = true;
spte = &sp->spt[page_offset / sizeof(*spte)];
while (npte--) {
entry = *spte;
mmu_pte_write_zap_pte(vcpu, sp, spte);
if (gentry)
mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
- mmu_pte_write_flush_tlb(vcpu, entry, *spte);
+ if (!remote_flush && need_remote_flush(entry, *spte))
+ remote_flush = true;
++spte;
}
}
+ mmu_pte_write_flush_tlb(vcpu, zap_page, remote_flush, local_flush);
kvm_mmu_commit_zap_page(vcpu->kvm);
kvm_mmu_audit(vcpu, "post pte write");
spin_unlock(&vcpu->kvm->mmu_lock);
--
1.6.1.2


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