KVM: x86: Deactivate APICv on vCPU with APIC disabled

APICv should be deactivated on vCPU that has APIC disabled.
Therefore, call kvm_vcpu_update_apicv() when changing
APIC mode, and add additional check for APIC disable mode
when determine APICV activation,
Suggested-by: NMaxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: NMaxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: NSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220519102709.24125-9-suravee.suthikulpanit@amd.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -2371,8 +2371,10 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 	if (((old_value ^ value) & X2APIC_ENABLE) && (value & X2APIC_ENABLE))
 		kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id);
 
-	if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE))
+	if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE)) {
+		kvm_vcpu_update_apicv(vcpu);
 		static_call_cond(kvm_x86_set_virtual_apic_mode)(vcpu);
+	}
 
 	apic->base_address = apic->vcpu->arch.apic_base &
 			     MSR_IA32_APICBASE_BASE;

arch/x86/kvm/x86.c

@@ -10065,7 +10065,9 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
 	down_read(&vcpu->kvm->arch.apicv_update_lock);
 	preempt_disable();
 
-	activate = kvm_vcpu_apicv_activated(vcpu);
+	/* Do not activate APICV when APIC is disabled */
+	activate = kvm_vcpu_apicv_activated(vcpu) &&
+		   (kvm_get_apic_mode(vcpu) != LAPIC_MODE_DISABLED);
 
 	if (apic->apicv_active == activate)
 		goto out;