qom: add object_new_with_class

Similar to CPU and machine classes, "-accel" class names are mangled,
so we have to first get a class via accel_find and then instantiate it.
Provide a new function to instantiate a class without going through
object_class_get_name, and use it for CPUs and machines already.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

accel/accel.c

@@ -48,9 +48,7 @@ AccelClass *accel_find(const char *opt_name)
 
 int accel_init_machine(AccelClass *acc, MachineState *ms)
 {
-    ObjectClass *oc = OBJECT_CLASS(acc);
+    AccelState *accel = ACCEL(object_new_with_class(OBJECT_CLASS(acc)));
-    const char *cname = object_class_get_name(oc);
-    AccelState *accel = ACCEL(object_new(cname));
     int ret;
     ms->accelerator = accel;
     *(acc->allowed) = true;

include/qom/object.h

@@ -592,6 +592,18 @@ struct InterfaceClass
     ((interface *)object_dynamic_cast_assert(OBJECT((obj)), (name), \
                                              __FILE__, __LINE__, __func__))
 
+/**
+ * object_new_with_class:
+ * @klass: The class to instantiate.
+ *
+ * This function will initialize a new object using heap allocated memory.
+ * The returned object has a reference count of 1, and will be freed when
+ * the last reference is dropped.
+ *
+ * Returns: The newly allocated and instantiated object.
+ */
+Object *object_new_with_class(ObjectClass *klass);
+
 /**
  * object_new:
  * @typename: The name of the type of the object to instantiate.

qom/object.c

@@ -658,6 +658,11 @@ static Object *object_new_with_type(Type type)
     return obj;
 }
 
+Object *object_new_with_class(ObjectClass *klass)
+{
+    return object_new_with_type(klass->type);
+}
+
 Object *object_new(const char *typename)
 {
     TypeImpl *ti = type_get_by_name(typename);

target/i386/cpu.c

@@ -4695,7 +4695,7 @@ static void x86_cpu_class_check_missing_features(X86CPUClass *xcc,
         return;
     }
 
-    xc = X86_CPU(object_new(object_class_get_name(OBJECT_CLASS(xcc))));
+    xc = X86_CPU(object_new_with_class(OBJECT_CLASS(xcc)));
 
     x86_cpu_expand_features(xc, &err);
     if (err) {
@@ -4763,7 +4763,7 @@ static GSList *get_sorted_cpu_model_list(void)
 
 static char *x86_cpu_class_get_model_id(X86CPUClass *xc)
 {
-    Object *obj = object_new(object_class_get_name(OBJECT_CLASS(xc)));
+    Object *obj = object_new_with_class(OBJECT_CLASS(xc));
     char *r = object_property_get_str(obj, "model-id", &error_abort);
     object_unref(obj);
     return r;
@@ -5141,7 +5141,7 @@ static X86CPU *x86_cpu_from_model(const char *model, QDict *props, Error **errp)
         goto out;
     }
 
-    xc = X86_CPU(object_new(object_class_get_name(OBJECT_CLASS(xcc))));
+    xc = X86_CPU(object_new_with_class(OBJECT_CLASS(xcc)));
     if (props) {
         object_apply_props(OBJECT(xc), props, &err);
         if (err) {
@@ -5983,7 +5983,7 @@ static void x86_cpu_apic_create(X86CPU *cpu, Error **errp)
     APICCommonState *apic;
     ObjectClass *apic_class = OBJECT_CLASS(apic_get_class());
 
-    cpu->apic_state = DEVICE(object_new(object_class_get_name(apic_class)));
+    cpu->apic_state = DEVICE(object_new_with_class(apic_class));
 
     object_property_add_child(OBJECT(cpu), "lapic",
                               OBJECT(cpu->apic_state), &error_abort);

target/s390x/cpu_models.c

@@ -440,7 +440,7 @@ static void create_cpu_model_list(ObjectClass *klass, void *opaque)
     if (cpu_list_data->model) {
         Object *obj;
         S390CPU *sc;
-        obj = object_new(object_class_get_name(klass));
+        obj = object_new_with_class(klass);
         sc = S390_CPU(obj);
         if (sc->model) {
             info->has_unavailable_features = true;
@@ -498,7 +498,7 @@ static void cpu_model_from_info(S390CPUModel *model, const CpuModelInfo *info,
         error_setg(errp, "The CPU definition '%s' requires KVM", info->name);
         return;
     }
-    obj = object_new(object_class_get_name(oc));
+    obj = object_new_with_class(oc);
     cpu = S390_CPU(obj);
 
     if (!cpu->model) {

vl.c

@@ -3834,8 +3834,7 @@ int main(int argc, char **argv, char **envp)
                       cleanup_add_fd, NULL, &error_fatal);
 #endif
 
-    current_machine = MACHINE(object_new(object_class_get_name(
+    current_machine = MACHINE(object_new_with_class(OBJECT_CLASS(machine_class)));
-                          OBJECT_CLASS(machine_class))));
     if (machine_help_func(qemu_get_machine_opts(), current_machine)) {
         exit(0);
     }