KVM: MMU: reduce remote tlb flush in kvm_mmu_pte_write()

collect remote tlb flush in kvm_mmu_pte_write() path

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 3b75689eda95..b285449e82b0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2666,11 +2666,15 @@ 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);
 }
 
@@ -2735,6 +2739,9 @@ 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);
 
@@ -2808,7 +2815,7 @@ 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);
-                        kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
+                        zap_page |= !!kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
                                                      &invalid_list);
                         ++vcpu->kvm->stat.mmu_flooded;
                         continue;
@@ -2833,16 +2840,19 @@ 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, &invalid_list);
         kvm_mmu_audit(vcpu, "post pte write");
         spin_unlock(&vcpu->kvm->mmu_lock);