KVM: VMX: Rewrite vmx_complete_interrupt()'s twisted maze of if() statements

...with a more straightforward switch().

Also fix a bug when NMI could be dropped on exit. Although this should
never happen in practice, since NMIs can only be injected, never triggered
internally by the guest like exceptions.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/vmx.c

@@ -3277,7 +3277,6 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
 	u8 vector;
 	int type;
 	bool idtv_info_valid;
-	u32 error;
 
 	idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
 	exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
@@ -3302,34 +3301,42 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
 		vmx->vnmi_blocked_time +=
 			ktime_to_ns(ktime_sub(ktime_get(), vmx->entry_time));
 
+	vmx->vcpu.arch.nmi_injected = false;
+	kvm_clear_exception_queue(&vmx->vcpu);
+	kvm_clear_interrupt_queue(&vmx->vcpu);
+
+	if (!idtv_info_valid)
+		return;
+
 	vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK;
 	type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK;
-	if (vmx->vcpu.arch.nmi_injected) {
+
+	switch(type) {
+	case INTR_TYPE_NMI_INTR:
+		vmx->vcpu.arch.nmi_injected = true;
 		/*
 		 * SDM 3: 27.7.1.2 (September 2008)
-		 * Clear bit "block by NMI" before VM entry if a NMI delivery
-		 * faulted.
+		 * Clear bit "block by NMI" before VM entry if a NMI
+		 * delivery faulted.
 		 */
-		if (idtv_info_valid && type == INTR_TYPE_NMI_INTR)
-			vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
-					GUEST_INTR_STATE_NMI);
-		else
-			vmx->vcpu.arch.nmi_injected = false;
-	}
-	kvm_clear_exception_queue(&vmx->vcpu);
-	if (idtv_info_valid && (type == INTR_TYPE_HARD_EXCEPTION ||
-				type == INTR_TYPE_SOFT_EXCEPTION)) {
+		vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
+				GUEST_INTR_STATE_NMI);
+		break;
+	case INTR_TYPE_HARD_EXCEPTION:
+	case INTR_TYPE_SOFT_EXCEPTION:
 		if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK) {
-			error = vmcs_read32(IDT_VECTORING_ERROR_CODE);
-			kvm_queue_exception_e(&vmx->vcpu, vector, error);
+			u32 err = vmcs_read32(IDT_VECTORING_ERROR_CODE);
+			kvm_queue_exception_e(&vmx->vcpu, vector, err);
 		} else
 			kvm_queue_exception(&vmx->vcpu, vector);
 		vmx->idt_vectoring_info = 0;
-	}
-	kvm_clear_interrupt_queue(&vmx->vcpu);
-	if (idtv_info_valid && type == INTR_TYPE_EXT_INTR) {
+		break;
+	case INTR_TYPE_EXT_INTR:
 		kvm_queue_interrupt(&vmx->vcpu, vector);
 		vmx->idt_vectoring_info = 0;
+		break;
+	default:
+		break;
 	}
 }