KVM: VMX: fix build without CONFIG_SMP

'apic' is not defined if !CONFIG_X86_64 && !CONFIG_X86_LOCAL_APIC.
Posted interrupt makes no sense without CONFIG_SMP, and
CONFIG_X86_LOCAL_APIC will be set with it.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -4367,6 +4367,18 @@ static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static inline bool kvm_vcpu_trigger_posted_interrupt(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_SMP
+	if (vcpu->mode == IN_GUEST_MODE) {
+		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
+				POSTED_INTR_VECTOR);
+		return true;
+	}
+#endif
+	return false;
+}
+
 static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
 						int vector)
 {
@@ -4375,9 +4387,7 @@ static int vmx_deliver_nested_posted_interrupt(struct kvm_vcpu *vcpu,
 	if (is_guest_mode(vcpu) &&
 	    vector == vmx->nested.posted_intr_nv) {
 		/* the PIR and ON have been set by L1. */
-		if (vcpu->mode == IN_GUEST_MODE)
-			apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
-				POSTED_INTR_VECTOR);
+		kvm_vcpu_trigger_posted_interrupt(vcpu);
 		/*
 		 * If a posted intr is not recognized by hardware,
 		 * we will accomplish it in the next vmentry.
@@ -4409,12 +4419,7 @@ static void vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector)
 
 	r = pi_test_and_set_on(&vmx->pi_desc);
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
-#ifdef CONFIG_SMP
-	if (!r && (vcpu->mode == IN_GUEST_MODE))
-		apic->send_IPI_mask(get_cpu_mask(vcpu->cpu),
-				POSTED_INTR_VECTOR);
-	else
-#endif
+	if (r || !kvm_vcpu_trigger_posted_interrupt(vcpu))
 		kvm_vcpu_kick(vcpu);
 }