target/s390x/cpu_models: Make kvm_s390_get_host_cpu_model() return bo…

…olean

As error.h suggested, the best practice for callee is to return
something to indicate success / failure.

So make kvm_s390_get_host_cpu_model() return boolean and check the
returned boolean in get_max_cpu_model() instead of accessing @err.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20240425031232.1586401-5-zhao1.liu@intel.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

target/s390x/cpu_models.c

@@ -560,16 +560,15 @@ S390CPUModel *get_max_cpu_model(Error **errp)
     }
 
     if (kvm_enabled()) {
-        kvm_s390_get_host_cpu_model(&max_model, &err);
+        if (!kvm_s390_get_host_cpu_model(&max_model, &err)) {
+            error_propagate(errp, err);
+            return NULL;
+        }
     } else {
         max_model.def = s390_find_cpu_def(QEMU_MAX_CPU_TYPE, QEMU_MAX_CPU_GEN,
                                           QEMU_MAX_CPU_EC_GA, NULL);
         bitmap_copy(max_model.features, qemu_max_cpu_feat, S390_FEAT_MAX);
     }
-    if (err) {
-        error_propagate(errp, err);
-        return NULL;
-    }
     cached = true;
     return &max_model;
 }

target/s390x/cpu_models.h

@@ -115,7 +115,7 @@ S390CPUDef const *s390_find_cpu_def(uint16_t type, uint8_t gen, uint8_t ec_ga,
                                     S390FeatBitmap features);
 
 bool kvm_s390_cpu_models_supported(void);
-void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp);
+bool kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp);
 void kvm_s390_apply_cpu_model(const S390CPUModel *model,  Error **errp);
 
 #endif /* TARGET_S390X_CPU_MODELS_H */

target/s390x/kvm/kvm.c

@@ -2375,7 +2375,7 @@ bool kvm_s390_cpu_models_supported(void)
                              KVM_S390_VM_CPU_MACHINE_SUBFUNC);
 }
 
-void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
+bool kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
 {
     struct kvm_s390_vm_cpu_machine prop = {};
     struct kvm_device_attr attr = {
@@ -2390,14 +2390,14 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
 
     if (!kvm_s390_cpu_models_supported()) {
         error_setg(errp, "KVM doesn't support CPU models");
-        return;
+        return false;
     }
 
     /* query the basic cpu model properties */
     rc = kvm_vm_ioctl(kvm_state, KVM_GET_DEVICE_ATTR, &attr);
     if (rc) {
         error_setg(errp, "KVM: Error querying host CPU model: %d", rc);
-        return;
+        return false;
     }
 
     cpu_type = cpuid_type(prop.cpuid);
@@ -2420,13 +2420,13 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
     rc = query_cpu_feat(model->features);
     if (rc) {
         error_setg(errp, "KVM: Error querying CPU features: %d", rc);
-        return;
+        return false;
     }
     /* get supported cpu subfunctions indicated via query / test bit */
     rc = query_cpu_subfunc(model->features);
     if (rc) {
         error_setg(errp, "KVM: Error querying CPU subfunctions: %d", rc);
-        return;
+        return false;
     }
 
     /* PTFF subfunctions might be indicated although kernel support missing */
@@ -2482,7 +2482,7 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
     }
     if (!model->def) {
         error_setg(errp, "KVM: host CPU model could not be identified");
-        return;
+        return false;
     }
     /* for now, we can only provide the AP feature with HW support */
     if (ap_available()) {
@@ -2506,6 +2506,7 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
     /* strip of features that are not part of the maximum model */
     bitmap_and(model->features, model->features, model->def->full_feat,
                S390_FEAT_MAX);
+    return true;
 }
 
 static int configure_uv_feat_guest(const S390FeatBitmap features)