KVM: x86: replace is_smm checks with kvm_x86_ops.smi_allowed

Do not hardcode is_smm so that all the architectural conditions for
blocking SMIs are listed in a single place.  Well, in two places because
this introduces some code duplication between Intel and AMD.

This ensures that nested SVM obeys GIF in kvm_vcpu_has_events.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.c

@@ -3783,7 +3783,7 @@ static bool svm_smi_allowed(struct kvm_vcpu *vcpu)
 		return false;
 	}
 
-	return true;
+	return !is_smm(vcpu);
 }
 
 static int svm_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate)

arch/x86/kvm/vmx/vmx.c

@@ -7680,7 +7680,7 @@ static bool vmx_smi_allowed(struct kvm_vcpu *vcpu)
 	/* we need a nested vmexit to enter SMM, postpone if run is pending */
 	if (to_vmx(vcpu)->nested.nested_run_pending)
 		return false;
-	return true;
+	return !is_smm(vcpu);
 }
 
 static int vmx_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate)

arch/x86/kvm/x86.c

@@ -7764,8 +7764,7 @@ static int inject_pending_event(struct kvm_vcpu *vcpu)
 	if (kvm_event_needs_reinjection(vcpu))
 		return 0;
 
-	if (vcpu->arch.smi_pending && !is_smm(vcpu) &&
-	    kvm_x86_ops.smi_allowed(vcpu)) {
+	if (vcpu->arch.smi_pending && kvm_x86_ops.smi_allowed(vcpu)) {
 		vcpu->arch.smi_pending = false;
 		++vcpu->arch.smi_count;
 		enter_smm(vcpu);
@@ -10206,7 +10205,8 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
 		return true;
 
 	if (kvm_test_request(KVM_REQ_SMI, vcpu) ||
-	    (vcpu->arch.smi_pending && !is_smm(vcpu)))
+	    (vcpu->arch.smi_pending &&
+	     kvm_x86_ops.smi_allowed(vcpu)))
 		return true;
 
 	if (kvm_arch_interrupt_allowed(vcpu) &&