KVM/MMU: Combine flushing remote tlb in mmu_set_spte()

mmu_set_spte() flushes remote tlbs for drop_parent_pte/drop_spte()
and set_spte() separately. This may introduce redundant flush. This
patch is to combine these flushes and check flush request after
calling set_spte().

Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
Reviewed-by: Junaid Shahid <junaids@google.com>
Reviewed-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 22a7984c68a51e9fbe039884dca3ef3ed9e424a7..8f216321d33b23a4da32c49d7454ebd367f42402 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2901,6 +2901,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
        int rmap_count;
        int set_spte_ret;
        int ret = RET_PF_RETRY;
+       bool flush = false;
 
        pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
                 *sptep, write_fault, gfn);
@@ -2917,12 +2918,12 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
 
                        child = page_header(pte & PT64_BASE_ADDR_MASK);
                        drop_parent_pte(child, sptep);
-                       kvm_flush_remote_tlbs(vcpu->kvm);
+                       flush = true;
                } else if (pfn != spte_to_pfn(*sptep)) {
                        pgprintk("hfn old %llx new %llx\n",
                                 spte_to_pfn(*sptep), pfn);
                        drop_spte(vcpu->kvm, sptep);
-                       kvm_flush_remote_tlbs(vcpu->kvm);
+                       flush = true;
                } else
                        was_rmapped = 1;
        }
@@ -2934,7 +2935,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
                        ret = RET_PF_EMULATE;
                kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
        }
-       if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH)
+       if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush)
                kvm_flush_remote_tlbs(vcpu->kvm);
 
        if (unlikely(is_mmio_spte(*sptep)))