KVM: nSVM: Report interrupts as allowed when in L2 and exit-on-interrupt is set

Report interrupts as allowed when the vCPU is in L2 and L2 is being run with
exit-on-interrupts enabled and EFLAGS.IF=1 (either on the host or on the guest
according to VINTR).  Interrupts are always unblocked from L1's perspective
in this case.

While moving nested_exit_on_intr to svm.h, use INTERCEPT_INTR properly instead
of assuming it's zero (which it is of course).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/nested.c

@@ -828,11 +828,6 @@ static void nested_svm_intr(struct vcpu_svm *svm)
 	nested_svm_vmexit(svm);
 }
 
-static bool nested_exit_on_intr(struct vcpu_svm *svm)
-{
-	return (svm->nested.intercept & 1ULL);
-}
-
 static int svm_check_nested_events(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);

arch/x86/kvm/svm/svm.c

@@ -3117,14 +3117,25 @@ bool svm_interrupt_blocked(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb;
 
-	if (!gif_set(svm) ||
-	     (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK))
+	if (!gif_set(svm))
 		return true;
 
-	if (is_guest_mode(vcpu) && (svm->vcpu.arch.hflags & HF_VINTR_MASK))
-		return !(svm->vcpu.arch.hflags & HF_HIF_MASK);
-	else
-		return !(kvm_get_rflags(vcpu) & X86_EFLAGS_IF);
+	if (is_guest_mode(vcpu)) {
+		/* As long as interrupts are being delivered...  */
+		if ((svm->vcpu.arch.hflags & HF_VINTR_MASK)
+		    ? !(svm->vcpu.arch.hflags & HF_HIF_MASK)
+		    : !(kvm_get_rflags(vcpu) & X86_EFLAGS_IF))
+			return true;
+
+		/* ... vmexits aren't blocked by the interrupt shadow  */
+		if (nested_exit_on_intr(svm))
+			return false;
+	} else {
+		if (!(kvm_get_rflags(vcpu) & X86_EFLAGS_IF))
+			return true;
+	}
+
+	return (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK);
 }
 
 static bool svm_interrupt_allowed(struct kvm_vcpu *vcpu)

arch/x86/kvm/svm/svm.h

@@ -386,6 +386,11 @@ static inline bool nested_exit_on_smi(struct vcpu_svm *svm)
 	return (svm->nested.intercept & (1ULL << INTERCEPT_SMI));
 }
 
+static inline bool nested_exit_on_intr(struct vcpu_svm *svm)
+{
+	return (svm->nested.intercept & (1ULL << INTERCEPT_INTR));
+}
+
 static inline bool nested_exit_on_nmi(struct vcpu_svm *svm)
 {
 	return (svm->nested.intercept & (1ULL << INTERCEPT_NMI));