KVM: x86: introduce ISA specific smi_allowed callback

Similar to NMI, there may be ISA specific reasons why an SMI cannot be
injected into the guest. This commit adds a new smi_allowed callback to
be implemented in following commits.

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c4e9b99..e3c61a3 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5401,6 +5401,11 @@ static void svm_setup_mce(struct kvm_vcpu *vcpu)
 	vcpu->arch.mcg_cap &= 0x1ff;
 }
 
+static int svm_smi_allowed(struct kvm_vcpu *vcpu)
+{
+	return 1;
+}
+
 static int svm_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
 {
 	/* TODO: Implement */
@@ -5524,6 +5529,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 	.update_pi_irte = svm_update_pi_irte,
 	.setup_mce = svm_setup_mce,
 
+	.smi_allowed = svm_smi_allowed,
 	.pre_enter_smm = svm_pre_enter_smm,
 	.pre_leave_smm = svm_pre_leave_smm,
 };