KVM: MMU: optimize pte write path if don't have protected sp

[~andy/linux] / arch / x86 / kvm / mmu.c

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bd14bb4c8594c4cb7b8375e6567e6a0aa56c61cc..b4ae7afa6b3bdbed2a089eeea2d4e7550a64375a 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -498,6 +498,7 @@ static void account_shadowed(struct kvm *kvm, gfn_t gfn)
                linfo = lpage_info_slot(gfn, slot, i);
                linfo->write_count += 1;
        }
+       kvm->arch.indirect_shadow_pages++;
 }
 
 static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn)
@@ -513,6 +514,7 @@ static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn)
                linfo->write_count -= 1;
                WARN_ON(linfo->write_count < 0);
        }
+       kvm->arch.indirect_shadow_pages--;
 }
 
 static int has_wrprotected_page(struct kvm *kvm,
@@ -565,7 +567,7 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
 
 static bool mapping_level_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t large_gfn)
 {
-       return gfn_to_memslot_dirty_bitmap(vcpu, large_gfn, true);
+       return !gfn_to_memslot_dirty_bitmap(vcpu, large_gfn, true);
 }
 
 static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn)
@@ -3233,6 +3235,13 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
        int level, npte, invlpg_counter, r, flooded = 0;
        bool remote_flush, local_flush, zap_page;
 
+       /*
+        * If we don't have indirect shadow pages, it means no page is
+        * write-protected, so we can exit simply.
+        */
+       if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages))
+               return;
+
        zap_page = remote_flush = local_flush = false;
        offset = offset_in_page(gpa);