KVM: SVM: Implement check_nested_events for NMI

Migrate nested guest NMI intercept processing
to new check_nested_events.
Signed-off-by: Cathy Avery <cavery@redhat.com>
Message-Id: <20200414201107.22952-2-cavery@redhat.com>
[Reorder clauses as NMIs have higher priority than IRQs; inject
 immediate vmexit as is now done for IRQ vmexits. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/nested.c

@@ -799,6 +799,20 @@ int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
 	return vmexit;
 }
 
+static bool nested_exit_on_nmi(struct vcpu_svm *svm)
+{
+	return (svm->nested.intercept & (1ULL << INTERCEPT_NMI));
+}
+
+static void nested_svm_nmi(struct vcpu_svm *svm)
+{
+	svm->vmcb->control.exit_code = SVM_EXIT_NMI;
+	svm->vmcb->control.exit_info_1 = 0;
+	svm->vmcb->control.exit_info_2 = 0;
+
+	nested_svm_vmexit(svm);
+}
+
 static void nested_svm_intr(struct vcpu_svm *svm)
 {
 	trace_kvm_nested_intr_vmexit(svm->vmcb->save.rip);
@@ -822,6 +836,13 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu)
 		kvm_event_needs_reinjection(vcpu) || svm->nested.exit_required ||
 		svm->nested.nested_run_pending;
 
+	if (vcpu->arch.nmi_pending && nested_exit_on_nmi(svm)) {
+		if (block_nested_events)
+			return -EBUSY;
+		nested_svm_nmi(svm);
+		return 0;
+	}
+
 	if (kvm_cpu_has_interrupt(vcpu) && nested_exit_on_intr(svm)) {
 		if (block_nested_events)
 			return -EBUSY;

arch/x86/kvm/svm/svm.c

@@ -3070,9 +3070,10 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb;
 	int ret;
+
 	ret = !(vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK) &&
 	      !(svm->vcpu.arch.hflags & HF_NMI_MASK);
-	ret = ret && gif_set(svm) && nested_svm_nmi(svm);
+	ret = ret && gif_set(svm);
 
 	return ret;
 }
@@ -3150,9 +3151,6 @@ static void enable_nmi_window(struct kvm_vcpu *vcpu)
 		return; /* STGI will cause a vm exit */
 	}
 
-	if (svm->nested.exit_required)
-		return; /* we're not going to run the guest yet */
-
 	/*
 	 * Something prevents NMI from been injected. Single step over possible
 	 * problem (IRET or exception injection or interrupt shadow)

arch/x86/kvm/svm/svm.h

@@ -373,21 +373,6 @@ void disable_nmi_singlestep(struct vcpu_svm *svm);
 #define NESTED_EXIT_DONE	1	/* Exit caused nested vmexit  */
 #define NESTED_EXIT_CONTINUE	2	/* Further checks needed      */
 
-/* This function returns true if it is save to enable the nmi window */
-static inline bool nested_svm_nmi(struct vcpu_svm *svm)
-{
-	if (!is_guest_mode(&svm->vcpu))
-		return true;
-
-	if (!(svm->nested.intercept & (1ULL << INTERCEPT_NMI)))
-		return true;
-
-	svm->vmcb->control.exit_code = SVM_EXIT_NMI;
-	svm->nested.exit_required = true;
-
-	return false;
-}
-
 static inline bool svm_nested_virtualize_tpr(struct kvm_vcpu *vcpu)
 {
 	return is_guest_mode(vcpu) && (vcpu->arch.hflags & HF_VINTR_MASK);