KVM/VMX: Change hv flush logic when ept tables are mismatched.

If ept table pointers are mismatched, flushing tlb for each vcpus via
hv flush interface still helps to reduce vmexits which are triggered
by IPI and INEPT emulation.
Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -1571,7 +1571,8 @@ static void check_ept_pointer_match(struct kvm *kvm)
 
 static int vmx_hv_remote_flush_tlb(struct kvm *kvm)
 {
-	int ret;
+	struct kvm_vcpu *vcpu;
+	int ret = -ENOTSUPP, i;
 
 	spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
 
@@ -1579,14 +1580,14 @@ static int vmx_hv_remote_flush_tlb(struct kvm *kvm)
 		check_ept_pointer_match(kvm);
 
 	if (to_kvm_vmx(kvm)->ept_pointers_match != EPT_POINTERS_MATCH) {
-		ret = -ENOTSUPP;
-		goto out;
-	}
-
+		kvm_for_each_vcpu(i, vcpu, kvm)
+			ret |= hyperv_flush_guest_mapping(
+				to_vmx(kvm_get_vcpu(kvm, i))->ept_pointer);
+	} else {
 		ret = hyperv_flush_guest_mapping(
 				to_vmx(kvm_get_vcpu(kvm, 0))->ept_pointer);
+	}
 
-out:
 	spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
 	return ret;
 }