KVM: SVM: Nullify vcpu_(un)blocking() hooks if AVIC is disabled

Nullify svm_x86_ops.vcpu_(un)blocking if AVIC/APICv is disabled as the
hooks are necessary only to clear the vCPU's IsRunning entry in the
Physical APIC and to update IRTE entries if the VM has a pass-through
device attached.

Opportunistically rename the helpers to clarify their AVIC relationship.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-24-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/avic.c

@@ -1027,7 +1027,7 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu)
 	WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
 }
 
-void svm_vcpu_blocking(struct kvm_vcpu *vcpu)
+void avic_vcpu_blocking(struct kvm_vcpu *vcpu)
 {
 	if (!kvm_vcpu_apicv_active(vcpu))
 		return;
@@ -1052,7 +1052,7 @@ void svm_vcpu_blocking(struct kvm_vcpu *vcpu)
 	preempt_enable();
 }
 
-void svm_vcpu_unblocking(struct kvm_vcpu *vcpu)
+void avic_vcpu_unblocking(struct kvm_vcpu *vcpu)
 {
 	int cpu;
 

arch/x86/kvm/svm/svm.c

@@ -4391,8 +4391,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.prepare_guest_switch = svm_prepare_guest_switch,
 	.vcpu_load = svm_vcpu_load,
 	.vcpu_put = svm_vcpu_put,
-	.vcpu_blocking = svm_vcpu_blocking,
-	.vcpu_unblocking = svm_vcpu_unblocking,
+	.vcpu_blocking = avic_vcpu_blocking,
+	.vcpu_unblocking = avic_vcpu_unblocking,
 
 	.update_exception_bitmap = svm_update_exception_bitmap,
 	.get_msr_feature = svm_get_msr_feature,
@@ -4682,6 +4682,9 @@ static __init int svm_hardware_setup(void)
 		pr_info("AVIC enabled\n");
 
 		amd_iommu_register_ga_log_notifier(&avic_ga_log_notifier);
+	} else {
+		svm_x86_ops.vcpu_blocking = NULL;
+		svm_x86_ops.vcpu_unblocking = NULL;
 	}
 
 	if (vls) {

arch/x86/kvm/svm/svm.h

@@ -592,8 +592,8 @@ int svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec);
 bool svm_dy_apicv_has_pending_interrupt(struct kvm_vcpu *vcpu);
 int svm_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
 		       uint32_t guest_irq, bool set);
-void svm_vcpu_blocking(struct kvm_vcpu *vcpu);
-void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
+void avic_vcpu_blocking(struct kvm_vcpu *vcpu);
+void avic_vcpu_unblocking(struct kvm_vcpu *vcpu);
 
 /* sev.c */