KVM: VMX: Add 'else' to split mutually exclusive case

Each if branch in handle_external_interrupt_irqoff() is mutually
exclusive. Add 'else' to make it clear and also avoid some unnecessary
check.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

@@ -6220,15 +6220,13 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
 	vmx->exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
 
 	/* if exit due to PF check for async PF */
-	if (is_page_fault(vmx->exit_intr_info))
+	if (is_page_fault(vmx->exit_intr_info)) {
 		vmx->vcpu.arch.apf.host_apf_reason = kvm_read_and_reset_pf_reason();
-
 	/* Handle machine checks before interrupts are enabled */
-	if (is_machine_check(vmx->exit_intr_info))
+	} else if (is_machine_check(vmx->exit_intr_info)) {
 		kvm_machine_check();
-
 	/* We need to handle NMIs before interrupts are enabled */
-	if (is_nmi(vmx->exit_intr_info)) {
+	} else if (is_nmi(vmx->exit_intr_info)) {
 		kvm_before_interrupt(&vmx->vcpu);
 		asm("int $2");
 		kvm_after_interrupt(&vmx->vcpu);