KVM: x86: allow per cpu apicv inhibit reasons

Add optional callback .vcpu_get_apicv_inhibit_reasons returning
extra inhibit reasons that prevent APICv from working on this vCPU.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322174050.241850-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm-x86-ops.h

@@ -126,6 +126,7 @@ KVM_X86_OP_OPTIONAL(migrate_timers)
 KVM_X86_OP(msr_filter_changed)
 KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
+KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
 
 #undef KVM_X86_OP
 #undef KVM_X86_OP_OPTIONAL

arch/x86/include/asm/kvm_host.h

@@ -1507,6 +1507,11 @@ struct kvm_x86_ops {
 	int (*complete_emulated_msr)(struct kvm_vcpu *vcpu, int err);
 
 	void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector);
+
+	/*
+	 * Returns vCPU specific APICv inhibit reasons
+	 */
+	unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu);
 };
 
 struct kvm_x86_nested_ops {
@@ -1807,6 +1812,7 @@ gpa_t kvm_mmu_gva_to_gpa_system(struct kvm_vcpu *vcpu, gva_t gva,
 				struct x86_exception *exception);
 
 bool kvm_apicv_activated(struct kvm *kvm);
+bool kvm_vcpu_apicv_activated(struct kvm_vcpu *vcpu);
 void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu);
 void __kvm_set_or_clear_apicv_inhibit(struct kvm *kvm,
 				      enum kvm_apicv_inhibit reason, bool set);

arch/x86/kvm/x86.c

@@ -9114,6 +9114,14 @@ bool kvm_apicv_activated(struct kvm *kvm)
 }
 EXPORT_SYMBOL_GPL(kvm_apicv_activated);
 
+bool kvm_vcpu_apicv_activated(struct kvm_vcpu *vcpu)
+{
+	ulong vm_reasons = READ_ONCE(vcpu->kvm->arch.apicv_inhibit_reasons);
+	ulong vcpu_reasons = static_call(kvm_x86_vcpu_get_apicv_inhibit_reasons)(vcpu);
+
+	return (vm_reasons | vcpu_reasons) == 0;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_apicv_activated);
 
 static void set_or_clear_apicv_inhibit(unsigned long *inhibits,
 				       enum kvm_apicv_inhibit reason, bool set)
@@ -9799,7 +9807,8 @@ void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
 
 	down_read(&vcpu->kvm->arch.apicv_update_lock);
 
-	activate = kvm_apicv_activated(vcpu->kvm);
+	activate = kvm_vcpu_apicv_activated(vcpu);
+
 	if (vcpu->arch.apicv_active == activate)
 		goto out;
 
@@ -10200,7 +10209,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 		 * per-VM state, and responsing vCPUs must wait for the update
 		 * to complete before servicing KVM_REQ_APICV_UPDATE.
 		 */
-		WARN_ON_ONCE(kvm_apicv_activated(vcpu->kvm) != kvm_vcpu_apicv_active(vcpu));
+		WARN_ON_ONCE(kvm_vcpu_apicv_activated(vcpu) != kvm_vcpu_apicv_active(vcpu));
 
 		exit_fastpath = static_call(kvm_x86_vcpu_run)(vcpu);
 		if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST))