vfio/mdev: simplify mdev_type handling

Instead of abusing struct attribute_group to control initialization of
struct mdev_type, just define the actual attributes in the mdev_driver,
allocate the mdev_type structures in the caller and pass them to
mdev_register_parent.

This allows the caller to use container_of to get at the containing
structure and thus significantly simplify the code.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Jason Gunthorpe <[e-mail]>
Reviewed-by: Tony Krowiak <[e-mail]>
Reviewed-by: Kevin Tian <[e-mail]>
Reviewed-by: Kirti Wankhede <[e-mail]>
Reviewed-by: Eric Farman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alex Williamson <[e-mail]>

Documentation/driver-api/vfio-mediated-device.rst

···
      struct mdev_driver {
 	     int  (*probe)  (struct mdev_device *dev);
 	     void (*remove) (struct mdev_device *dev);
-	     struct attribute_group **supported_type_groups;
+	     const struct attribute * const *types_attrs;
 	     struct device_driver    driver;
      };
 

drivers/gpu/drm/i915/gvt/gvt.h

···
 	const char *name;
 };
 
-#define NR_MAX_INTEL_VGPU_TYPES 20
 struct intel_vgpu_type {
+	struct mdev_type type;
 	char name[16];
 	const struct intel_vgpu_config *conf;
 	unsigned int avail_instance;
···
 	struct notifier_block shadow_ctx_notifier_block[I915_NUM_ENGINES];
 	DECLARE_HASHTABLE(cmd_table, GVT_CMD_HASH_BITS);
 	struct mdev_parent parent;
+	struct mdev_type **mdev_types;
 	struct intel_vgpu_type *types;
 	unsigned int num_types;
 	struct intel_vgpu *idle_vgpu;

drivers/gpu/drm/i915/gvt/kvmgt.c

···
 					struct mdev_type_attribute *attr,
 					char *buf)
 {
-	struct intel_vgpu_type *type;
-	unsigned int num = 0;
-	struct intel_gvt *gvt = kdev_to_i915(mtype_get_parent_dev(mtype))->gvt;
+	struct intel_vgpu_type *type =
+		container_of(mtype, struct intel_vgpu_type, type);
 
-	type = &gvt->types[mtype_get_type_group_id(mtype)];
-	if (!type)
-		num = 0;
-	else
-		num = type->avail_instance;
-
-	return sprintf(buf, "%u\n", num);
+	return sprintf(buf, "%u\n", type->avail_instance);
 }
 
 static ssize_t device_api_show(struct mdev_type *mtype,
···
 static ssize_t description_show(struct mdev_type *mtype,
 				struct mdev_type_attribute *attr, char *buf)
 {
-	struct intel_vgpu_type *type;
-	struct intel_gvt *gvt = kdev_to_i915(mtype_get_parent_dev(mtype))->gvt;
-
-	type = &gvt->types[mtype_get_type_group_id(mtype)];
-	if (!type)
-		return 0;
+	struct intel_vgpu_type *type =
+		container_of(mtype, struct intel_vgpu_type, type);
 
 	return sprintf(buf, "low_gm_size: %dMB\nhigh_gm_size: %dMB\n"
 		       "fence: %d\nresolution: %s\n"
···
 static ssize_t name_show(struct mdev_type *mtype,
 			 struct mdev_type_attribute *attr, char *buf)
 {
-	struct intel_vgpu_type *type;
-	struct intel_gvt *gvt = kdev_to_i915(mtype_get_parent_dev(mtype))->gvt;
-
-	type = &gvt->types[mtype_get_type_group_id(mtype)];
-	if (!type)
-		return 0;
-
-	return sprintf(buf, "%s\n", type->name);
+	return sprintf(buf, "%s\n", mtype->sysfs_name);
 }
 
 static MDEV_TYPE_ATTR_RO(available_instances);
···
 static MDEV_TYPE_ATTR_RO(description);
 static MDEV_TYPE_ATTR_RO(name);
 
-static struct attribute *gvt_type_attrs[] = {
+static const struct attribute *gvt_type_attrs[] = {
 	&mdev_type_attr_available_instances.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_description.attr,
 	&mdev_type_attr_name.attr,
 	NULL,
 };
-
-static struct attribute_group *gvt_vgpu_type_groups[] = {
-	[0 ... NR_MAX_INTEL_VGPU_TYPES - 1] = NULL,
-};
-
-static int intel_gvt_init_vgpu_type_groups(struct intel_gvt *gvt)
-{
-	int i, j;
-	struct intel_vgpu_type *type;
-	struct attribute_group *group;
-
-	for (i = 0; i < gvt->num_types; i++) {
-		type = &gvt->types[i];
-
-		group = kzalloc(sizeof(struct attribute_group), GFP_KERNEL);
-		if (!group)
-			goto unwind;
-
-		group->name = type->name;
-		group->attrs = gvt_type_attrs;
-		gvt_vgpu_type_groups[i] = group;
-	}
-
-	return 0;
-
-unwind:
-	for (j = 0; j < i; j++) {
-		group = gvt_vgpu_type_groups[j];
-		kfree(group);
-	}
-
-	return -ENOMEM;
-}
-
-static void intel_gvt_cleanup_vgpu_type_groups(struct intel_gvt *gvt)
-{
-	int i;
-	struct attribute_group *group;
-
-	for (i = 0; i < gvt->num_types; i++) {
-		group = gvt_vgpu_type_groups[i];
-		gvt_vgpu_type_groups[i] = NULL;
-		kfree(group);
-	}
-}
 
 static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 		unsigned long size)
···
 static int intel_vgpu_init_dev(struct vfio_device *vfio_dev)
 {
 	struct mdev_device *mdev = to_mdev_device(vfio_dev->dev);
-	struct device *pdev = mdev_parent_dev(mdev);
-	struct intel_gvt *gvt = kdev_to_i915(pdev)->gvt;
-	struct intel_vgpu_type *type;
 	struct intel_vgpu *vgpu = vfio_dev_to_vgpu(vfio_dev);
+	struct intel_vgpu_type *type =
+		container_of(mdev->type, struct intel_vgpu_type, type);
 
-	type = &gvt->types[mdev_get_type_group_id(mdev)];
-	if (!type)
-		return -EINVAL;
-
-	vgpu->gvt = gvt;
+	vgpu->gvt = kdev_to_i915(mdev_parent_dev(mdev))->gvt;
 	return intel_gvt_create_vgpu(vgpu, type->conf);
 }
 
···
 	},
 	.probe		= intel_vgpu_probe,
 	.remove		= intel_vgpu_remove,
-	.supported_type_groups	= gvt_vgpu_type_groups,
+	.types_attrs	= gvt_type_attrs,
 };
 
 int intel_gvt_page_track_add(struct intel_vgpu *info, u64 gfn)
···
 		return;
 
 	mdev_unregister_parent(&gvt->parent);
-	intel_gvt_cleanup_vgpu_type_groups(gvt);
 	intel_gvt_destroy_idle_vgpu(gvt->idle_vgpu);
 	intel_gvt_clean_vgpu_types(gvt);
 
···
 
 	intel_gvt_debugfs_init(gvt);
 
-	ret = intel_gvt_init_vgpu_type_groups(gvt);
+	ret = mdev_register_parent(&gvt->parent, i915->drm.dev,
+				   &intel_vgpu_mdev_driver,
+				   gvt->mdev_types, gvt->num_types);
 	if (ret)
 		goto out_destroy_idle_vgpu;
-
-	ret = mdev_register_parent(&gvt->parent, i915->drm.dev,
-				   &intel_vgpu_mdev_driver);
-	if (ret)
-		goto out_cleanup_vgpu_type_groups;
 
 	gvt_dbg_core("gvt device initialization is done\n");
 	return 0;
 
-out_cleanup_vgpu_type_groups:
-	intel_gvt_cleanup_vgpu_type_groups(gvt);
 out_destroy_idle_vgpu:
 	intel_gvt_destroy_idle_vgpu(gvt->idle_vgpu);
 	intel_gvt_debugfs_clean(gvt);

drivers/gpu/drm/i915/gvt/vgpu.c

···
 	if (!gvt->types)
 		return -ENOMEM;
 
+	gvt->mdev_types = kcalloc(num_types, sizeof(*gvt->mdev_types),
+			     GFP_KERNEL);
+	if (!gvt->mdev_types)
+		goto out_free_types;
+
 	for (i = 0; i < num_types; ++i) {
 		const struct intel_vgpu_config *conf = &intel_vgpu_configs[i];
 
 		if (low_avail / conf->low_mm == 0)
 			break;
 		if (conf->weight < 1 || conf->weight > VGPU_MAX_WEIGHT)
-			goto out_free_types;
+			goto out_free_mdev_types;
 
 		sprintf(gvt->types[i].name, "GVTg_V%u_%s",
 			GRAPHICS_VER(gvt->gt->i915) == 8 ? 4 : 5, conf->name);
···
 			     i, gvt->types[i].name, gvt->types[i].avail_instance,
 			     conf->low_mm, conf->high_mm, conf->fence,
 			     conf->weight, vgpu_edid_str(conf->edid));
+
+		gvt->mdev_types[i] = &gvt->types[i].type;
+		gvt->mdev_types[i]->sysfs_name = gvt->types[i].name;
 	}
 
 	gvt->num_types = i;
 	return 0;
 
+out_free_mdev_types:
+	kfree(gvt->mdev_types);
 out_free_types:
 	kfree(gvt->types);
 	return -EINVAL;
···
 
 void intel_gvt_clean_vgpu_types(struct intel_gvt *gvt)
 {
+	kfree(gvt->mdev_types);
 	kfree(gvt->types);
 }
 

drivers/s390/cio/vfio_ccw_drv.c

···
 	mutex_destroy(&private->io_mutex);
 	kfree(private);
 }
-
 static int vfio_ccw_sch_probe(struct subchannel *sch)
 {
 	struct pmcw *pmcw = &sch->schib.pmcw;
···
 
 	dev_set_drvdata(&sch->dev, private);
 
+	private->mdev_type.sysfs_name = "io";
+	private->mdev_types[0] = &private->mdev_type;
 	ret = mdev_register_parent(&private->parent, &sch->dev,
-				   &vfio_ccw_mdev_driver);
+				   &vfio_ccw_mdev_driver,
+				   private->mdev_types, 1);
 	if (ret)
 		goto out_free;
 

drivers/s390/cio/vfio_ccw_ops.c

···
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static struct attribute *mdev_types_attrs[] = {
+static const struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
-	NULL,
-};
-
-static struct attribute_group mdev_type_group = {
-	.name  = "io",
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group *mdev_type_groups[] = {
-	&mdev_type_group,
 	NULL,
 };
 
···
 	},
 	.probe = vfio_ccw_mdev_probe,
 	.remove = vfio_ccw_mdev_remove,
-	.supported_type_groups  = mdev_type_groups,
+	.types_attrs = mdev_types_attrs,
 };

drivers/s390/cio/vfio_ccw_private.h

···
 	struct completion	release_comp;
 
 	struct mdev_parent	parent;
+	struct mdev_type	mdev_type;
+	struct mdev_type	*mdev_types[1];
 } __aligned(8);
 
 int vfio_ccw_sch_quiesce(struct subchannel *sch);

drivers/s390/crypto/vfio_ap_ops.c

···
 
 static MDEV_TYPE_ATTR_RO(device_api);
 
-static struct attribute *vfio_ap_mdev_type_attrs[] = {
+static const struct attribute *vfio_ap_mdev_type_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
-	NULL,
-};
-
-static struct attribute_group vfio_ap_mdev_hwvirt_type_group = {
-	.name = VFIO_AP_MDEV_TYPE_HWVIRT,
-	.attrs = vfio_ap_mdev_type_attrs,
-};
-
-static struct attribute_group *vfio_ap_mdev_type_groups[] = {
-	&vfio_ap_mdev_hwvirt_type_group,
 	NULL,
 };
 
···
 	},
 	.probe = vfio_ap_mdev_probe,
 	.remove = vfio_ap_mdev_remove,
-	.supported_type_groups = vfio_ap_mdev_type_groups,
+	.types_attrs = vfio_ap_mdev_type_attrs,
 };
 
 int vfio_ap_mdev_register(void)
···
 	if (ret)
 		return ret;
 
+	matrix_dev->mdev_type.sysfs_name = VFIO_AP_MDEV_TYPE_HWVIRT;
+	matrix_dev->mdev_types[0] = &matrix_dev->mdev_type;
 	ret = mdev_register_parent(&matrix_dev->parent, &matrix_dev->device,
-				   &vfio_ap_matrix_driver);
+				   &vfio_ap_matrix_driver,
+				   matrix_dev->mdev_types, 1);
 	if (ret)
 		goto err_driver;
 	return 0;

drivers/s390/crypto/vfio_ap_private.h

···
 	struct ap_driver  *vfio_ap_drv;
 	struct mutex guests_lock; /* serializes access to each KVM guest */
 	struct mdev_parent parent;
+	struct mdev_type mdev_type;
+	struct mdev_type *mdev_types[];
 };
 
 extern struct ap_matrix_dev *matrix_dev;

drivers/vfio/mdev/mdev_core.c

···
 EXPORT_SYMBOL(mdev_parent_dev);
 
 /*
- * Return the index in supported_type_groups that this mdev_device was created
- * from.
- */
-unsigned int mdev_get_type_group_id(struct mdev_device *mdev)
-{
-	return mdev->type->type_group_id;
-}
-EXPORT_SYMBOL(mdev_get_type_group_id);
-
-/*
- * Used in mdev_type_attribute sysfs functions to return the index in the
- * supported_type_groups that the sysfs is called from.
- */
-unsigned int mtype_get_type_group_id(struct mdev_type *mtype)
-{
-	return mtype->type_group_id;
-}
-EXPORT_SYMBOL(mtype_get_type_group_id);
-
-/*
  * Used in mdev_type_attribute sysfs functions to return the parent struct
  * device
  */
···
  * @parent: parent structure registered
  * @dev: device structure representing parent device.
  * @mdev_driver: Device driver to bind to the newly created mdev
+ * @types: Array of supported mdev types
+ * @nr_types: Number of entries in @types
  *
  * Registers the @parent stucture as a parent for mdev types and thus mdev
  * devices.  The caller needs to hold a reference on @dev that must not be
···
  * Returns a negative value on error, otherwise 0.
  */
 int mdev_register_parent(struct mdev_parent *parent, struct device *dev,
-		struct mdev_driver *mdev_driver)
+		struct mdev_driver *mdev_driver, struct mdev_type **types,
+		unsigned int nr_types)
 {
 	char *env_string = "MDEV_STATE=registered";
 	char *envp[] = { env_string, NULL };
 	int ret;
 
-	/* check for mandatory ops */
-	if (!mdev_driver->supported_type_groups)
-		return -EINVAL;
-
 	memset(parent, 0, sizeof(*parent));
 	init_rwsem(&parent->unreg_sem);
 	parent->dev = dev;
 	parent->mdev_driver = mdev_driver;
+	parent->types = types;
+	parent->nr_types = nr_types;
 
 	if (!mdev_bus_compat_class) {
 		mdev_bus_compat_class = class_compat_register("mdev_bus");

drivers/vfio/mdev/mdev_driver.c

···
  **/
 int mdev_register_driver(struct mdev_driver *drv)
 {
-	/* initialize common driver fields */
+	if (!drv->types_attrs)
+		return -EINVAL;
 	drv->driver.bus = &mdev_bus_type;
-
-	/* register with core */
 	return driver_register(&drv->driver);
 }
 EXPORT_SYMBOL(mdev_register_driver);

drivers/vfio/mdev/mdev_private.h

···
 int  mdev_bus_register(void);
 void mdev_bus_unregister(void);
 
-struct mdev_type {
-	struct kobject kobj;
-	struct kobject *devices_kobj;
-	struct mdev_parent *parent;
-	struct list_head next;
-	unsigned int type_group_id;
-};
-
 extern const struct attribute_group *mdev_device_groups[];
 
 #define to_mdev_type_attr(_attr)	\

drivers/vfio/mdev/mdev_sysfs.c

···
 	pr_debug("Releasing group %s\n", kobj->name);
 	/* Pairs with the get in add_mdev_supported_type() */
 	put_device(type->parent->dev);
-	kfree(type);
 }
 
 static struct kobj_type mdev_type_ktype = {
···
 	.release = mdev_type_release,
 };
 
-static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
-						 unsigned int type_group_id)
+static int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
 {
-	struct mdev_type *type;
-	struct attribute_group *group =
-		parent->mdev_driver->supported_type_groups[type_group_id];
 	int ret;
-
-	if (!group->name) {
-		pr_err("%s: Type name empty!\n", __func__);
-		return ERR_PTR(-EINVAL);
-	}
-
-	type = kzalloc(sizeof(*type), GFP_KERNEL);
-	if (!type)
-		return ERR_PTR(-ENOMEM);
 
 	type->kobj.kset = parent->mdev_types_kset;
 	type->parent = parent;
 	/* Pairs with the put in mdev_type_release() */
 	get_device(parent->dev);
-	type->type_group_id = type_group_id;
 
 	ret = kobject_init_and_add(&type->kobj, &mdev_type_ktype, NULL,
 				   "%s-%s", dev_driver_string(parent->dev),
-				   group->name);
+				   type->sysfs_name);
 	if (ret) {
 		kobject_put(&type->kobj);
-		return ERR_PTR(ret);
+		return ret;
 	}
 
 	ret = sysfs_create_file(&type->kobj, &mdev_type_attr_create.attr);
···
 		goto attr_devices_failed;
 	}
 
-	ret = sysfs_create_files(&type->kobj,
-				 (const struct attribute **)group->attrs);
-	if (ret) {
-		ret = -ENOMEM;
+	ret = sysfs_create_files(&type->kobj, parent->mdev_driver->types_attrs);
+	if (ret)
 		goto attrs_failed;
-	}
-	return type;
+	return 0;
 
 attrs_failed:
 	kobject_put(type->devices_kobj);
···
 attr_create_failed:
 	kobject_del(&type->kobj);
 	kobject_put(&type->kobj);
-	return ERR_PTR(ret);
+	return ret;
 }
 
-static void remove_mdev_supported_type(struct mdev_type *type)
+static void mdev_type_remove(struct mdev_type *type)
 {
-	struct attribute_group *group =
-		type->parent->mdev_driver->supported_type_groups[type->type_group_id];
+	sysfs_remove_files(&type->kobj, type->parent->mdev_driver->types_attrs);
 
-	sysfs_remove_files(&type->kobj,
-			   (const struct attribute **)group->attrs);
 	kobject_put(type->devices_kobj);
 	sysfs_remove_file(&type->kobj, &mdev_type_attr_create.attr);
 	kobject_del(&type->kobj);
 	kobject_put(&type->kobj);
 }
 
-static int add_mdev_supported_type_groups(struct mdev_parent *parent)
-{
-	int i;
-
-	for (i = 0; parent->mdev_driver->supported_type_groups[i]; i++) {
-		struct mdev_type *type;
-
-		type = add_mdev_supported_type(parent, i);
-		if (IS_ERR(type)) {
-			struct mdev_type *ltype, *tmp;
-
-			list_for_each_entry_safe(ltype, tmp, &parent->type_list,
-						  next) {
-				list_del(&ltype->next);
-				remove_mdev_supported_type(ltype);
-			}
-			return PTR_ERR(type);
-		}
-		list_add(&type->next, &parent->type_list);
-	}
-	return 0;
-}
-
 /* mdev sysfs functions */
 void parent_remove_sysfs_files(struct mdev_parent *parent)
 {
-	struct mdev_type *type, *tmp;
+	int i;
 
-	list_for_each_entry_safe(type, tmp, &parent->type_list, next) {
-		list_del(&type->next);
-		remove_mdev_supported_type(type);
-	}
-
+	for (i = 0; i < parent->nr_types; i++)
+		mdev_type_remove(parent->types[i]);
 	kset_unregister(parent->mdev_types_kset);
 }
 
 int parent_create_sysfs_files(struct mdev_parent *parent)
 {
-	int ret;
+	int ret, i;
 
 	parent->mdev_types_kset = kset_create_and_add("mdev_supported_types",
 					       NULL, &parent->dev->kobj);
-
 	if (!parent->mdev_types_kset)
 		return -ENOMEM;
 
-	INIT_LIST_HEAD(&parent->type_list);
-
-	ret = add_mdev_supported_type_groups(parent);
-	if (ret)
-		goto create_err;
+	for (i = 0; i < parent->nr_types; i++) {
+		ret = mdev_type_add(parent, parent->types[i]);
+		if (ret)
+			goto out_err;
+	}
 	return 0;
 
-create_err:
-	kset_unregister(parent->mdev_types_kset);
-	return ret;
+out_err:
+	while (--i >= 0)
+		mdev_type_remove(parent->types[i]);
+	return 0;
 }
 
 static ssize_t remove_store(struct device *dev, struct device_attribute *attr,

include/linux/mdev.h

···
 	bool active;
 };
 
+struct mdev_type {
+	/* set by the driver before calling mdev_register parent: */
+	const char *sysfs_name;
+
+	/* set by the core, can be used drivers */
+	struct mdev_parent *parent;
+
+	/* internal only */
+	struct kobject kobj;
+	struct kobject *devices_kobj;
+};
+
 /* embedded into the struct device that the mdev devices hang off */
 struct mdev_parent {
 	struct device *dev;
 	struct mdev_driver *mdev_driver;
 	struct kset *mdev_types_kset;
-	struct list_head type_list;
 	/* Synchronize device creation/removal with parent unregistration */
 	struct rw_semaphore unreg_sem;
+	struct mdev_type **types;
+	unsigned int nr_types;
 };
 
 static inline struct mdev_device *to_mdev_device(struct device *dev)
···
 	return container_of(dev, struct mdev_device, dev);
 }
 
-unsigned int mdev_get_type_group_id(struct mdev_device *mdev);
-unsigned int mtype_get_type_group_id(struct mdev_type *mtype);
 struct device *mtype_get_parent_dev(struct mdev_type *mtype);
 
 /* interface for exporting mdev supported type attributes */
···
  * struct mdev_driver - Mediated device driver
  * @probe: called when new device created
  * @remove: called when device removed
- * @supported_type_groups: Attributes to define supported types. It is mandatory
- *			to provide supported types.
+ * @types_attrs: attributes to the type kobjects.
  * @driver: device driver structure
- *
  **/
 struct mdev_driver {
 	int (*probe)(struct mdev_device *dev);
 	void (*remove)(struct mdev_device *dev);
-	struct attribute_group **supported_type_groups;
+	const struct attribute * const *types_attrs;
 	struct device_driver driver;
 };
 
 extern struct bus_type mdev_bus_type;
 
 int mdev_register_parent(struct mdev_parent *parent, struct device *dev,
-		struct mdev_driver *mdev_driver);
+		struct mdev_driver *mdev_driver, struct mdev_type **types,
+		unsigned int nr_types);
 void mdev_unregister_parent(struct mdev_parent *parent);
 
 int mdev_register_driver(struct mdev_driver *drv);

samples/vfio-mdev/mbochs.c

···
 #define MBOCHS_TYPE_2 "medium"
 #define MBOCHS_TYPE_3 "large"
 
-static const struct mbochs_type {
+static struct mbochs_type {
+	struct mdev_type type;
 	const char *name;
 	u32 mbytes;
 	u32 max_x;
 	u32 max_y;
 } mbochs_types[] = {
 	{
+		.type.sysfs_name	= MBOCHS_TYPE_1,
 		.name	= MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_1,
 		.mbytes = 4,
 		.max_x  = 800,
 		.max_y  = 600,
 	}, {
+		.type.sysfs_name	= MBOCHS_TYPE_2,
 		.name	= MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_2,
 		.mbytes = 16,
 		.max_x  = 1920,
 		.max_y  = 1440,
 	}, {
+		.type.sysfs_name	= MBOCHS_TYPE_3,
 		.name	= MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_3,
 		.mbytes = 64,
 		.max_x  = 0,
···
 	},
 };
 
+static struct mdev_type *mbochs_mdev_types[] = {
+	&mbochs_types[0].type,
+	&mbochs_types[1].type,
+	&mbochs_types[2].type,
+};
 
 static dev_t		mbochs_devt;
 static struct class	*mbochs_class;
···
 	struct mdev_state *mdev_state =
 		container_of(vdev, struct mdev_state, vdev);
 	struct mdev_device *mdev = to_mdev_device(vdev->dev);
-	const struct mbochs_type *type =
-		&mbochs_types[mdev_get_type_group_id(mdev)];
+	struct mbochs_type *type =
+		container_of(mdev->type, struct mbochs_type, type);
 	int avail_mbytes = atomic_read(&mbochs_avail_mbytes);
 	int ret = -ENOMEM;
 
···
 static ssize_t name_show(struct mdev_type *mtype,
 			 struct mdev_type_attribute *attr, char *buf)
 {
-	const struct mbochs_type *type =
-		&mbochs_types[mtype_get_type_group_id(mtype)];
+	struct mbochs_type *type =
+		container_of(mtype, struct mbochs_type, type);
 
 	return sprintf(buf, "%s\n", type->name);
 }
···
 static ssize_t description_show(struct mdev_type *mtype,
 				struct mdev_type_attribute *attr, char *buf)
 {
-	const struct mbochs_type *type =
-		&mbochs_types[mtype_get_type_group_id(mtype)];
+	struct mbochs_type *type =
+		container_of(mtype, struct mbochs_type, type);
 
 	return sprintf(buf, "virtual display, %d MB video memory\n",
 		       type ? type->mbytes  : 0);
···
 					struct mdev_type_attribute *attr,
 					char *buf)
 {
-	const struct mbochs_type *type =
-		&mbochs_types[mtype_get_type_group_id(mtype)];
+	struct mbochs_type *type =
+		container_of(mtype, struct mbochs_type, type);
 	int count = atomic_read(&mbochs_avail_mbytes) / type->mbytes;
 
 	return sprintf(buf, "%d\n", count);
···
 }
 static MDEV_TYPE_ATTR_RO(device_api);
 
-static struct attribute *mdev_types_attrs[] = {
+static const struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_description.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
-	NULL,
-};
-
-static struct attribute_group mdev_type_group1 = {
-	.name  = MBOCHS_TYPE_1,
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group mdev_type_group2 = {
-	.name  = MBOCHS_TYPE_2,
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group mdev_type_group3 = {
-	.name  = MBOCHS_TYPE_3,
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group *mdev_type_groups[] = {
-	&mdev_type_group1,
-	&mdev_type_group2,
-	&mdev_type_group3,
 	NULL,
 };
 
···
 	},
 	.probe = mbochs_probe,
 	.remove	= mbochs_remove,
-	.supported_type_groups = mdev_type_groups,
+	.types_attrs = mdev_types_attrs,
 };
 
 static const struct file_operations vd_fops = {
···
 	if (ret)
 		goto err_class;
 
-	ret = mdev_register_parent(&mbochs_parent, &mbochs_dev, &mbochs_driver);
+	ret = mdev_register_parent(&mbochs_parent, &mbochs_dev, &mbochs_driver,
+				   mbochs_mdev_types,
+				   ARRAY_SIZE(mbochs_mdev_types));
 	if (ret)
 		goto err_device;
 

samples/vfio-mdev/mdpy.c

···
 #define MDPY_TYPE_2 "xga"
 #define MDPY_TYPE_3 "hd"
 
-static const struct mdpy_type {
+static struct mdpy_type {
+	struct mdev_type type;
 	const char *name;
 	u32 format;
 	u32 bytepp;
···
 	u32 height;
 } mdpy_types[] = {
 	{
+		.type.sysfs_name 	= MDPY_TYPE_1,
 		.name	= MDPY_CLASS_NAME "-" MDPY_TYPE_1,
 		.format = DRM_FORMAT_XRGB8888,
 		.bytepp = 4,
 		.width	= 640,
 		.height = 480,
 	}, {
+		.type.sysfs_name 	= MDPY_TYPE_2,
 		.name	= MDPY_CLASS_NAME "-" MDPY_TYPE_2,
 		.format = DRM_FORMAT_XRGB8888,
 		.bytepp = 4,
 		.width	= 1024,
 		.height = 768,
 	}, {
+		.type.sysfs_name 	= MDPY_TYPE_3,
 		.name	= MDPY_CLASS_NAME "-" MDPY_TYPE_3,
 		.format = DRM_FORMAT_XRGB8888,
 		.bytepp = 4,
 		.width	= 1920,
 		.height = 1080,
 	},
+};
+
+static struct mdev_type *mdpy_mdev_types[] = {
+	&mdpy_types[0].type,
+	&mdpy_types[1].type,
+	&mdpy_types[2].type,
 };
 
 static dev_t		mdpy_devt;
···
 		container_of(vdev, struct mdev_state, vdev);
 	struct mdev_device *mdev = to_mdev_device(vdev->dev);
 	const struct mdpy_type *type =
-		&mdpy_types[mdev_get_type_group_id(mdev)];
+		container_of(mdev->type, struct mdpy_type, type);
 	u32 fbsize;
 	int ret = -ENOMEM;
 
···
 static ssize_t name_show(struct mdev_type *mtype,
 			 struct mdev_type_attribute *attr, char *buf)
 {
-	const struct mdpy_type *type =
-		&mdpy_types[mtype_get_type_group_id(mtype)];
+	struct mdpy_type *type = container_of(mtype, struct mdpy_type, type);
 
 	return sprintf(buf, "%s\n", type->name);
 }
···
 static ssize_t description_show(struct mdev_type *mtype,
 				struct mdev_type_attribute *attr, char *buf)
 {
-	const struct mdpy_type *type =
-		&mdpy_types[mtype_get_type_group_id(mtype)];
+	struct mdpy_type *type = container_of(mtype, struct mdpy_type, type);
 
 	return sprintf(buf, "virtual display, %dx%d framebuffer\n",
 		       type->width, type->height);
···
 }
 static MDEV_TYPE_ATTR_RO(device_api);
 
-static struct attribute *mdev_types_attrs[] = {
+static const struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_description.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
-	NULL,
-};
-
-static struct attribute_group mdev_type_group1 = {
-	.name  = MDPY_TYPE_1,
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group mdev_type_group2 = {
-	.name  = MDPY_TYPE_2,
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group mdev_type_group3 = {
-	.name  = MDPY_TYPE_3,
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group *mdev_type_groups[] = {
-	&mdev_type_group1,
-	&mdev_type_group2,
-	&mdev_type_group3,
 	NULL,
 };
 
···
 	},
 	.probe = mdpy_probe,
 	.remove	= mdpy_remove,
-	.supported_type_groups = mdev_type_groups,
+	.types_attrs = mdev_types_attrs,
 };
 
 static const struct file_operations vd_fops = {
···
 	if (ret)
 		goto err_class;
 
-	ret = mdev_register_parent(&mdpy_parent, &mdpy_dev, &mdpy_driver);
+	ret = mdev_register_parent(&mdpy_parent, &mdpy_dev, &mdpy_driver,
+				   mdpy_mdev_types,
+				   ARRAY_SIZE(mdpy_mdev_types));
 	if (ret)
 		goto err_device;
 

samples/vfio-mdev/mtty.c

···
 	int nr_ports;
 };
 
+static struct mtty_type {
+	struct mdev_type type;
+	int nr_ports;
+	const char *name;
+} mtty_types[2] = {
+	{ .nr_ports = 1, .type.sysfs_name = "1", .name = "Single port serial" },
+	{ .nr_ports = 2, .type.sysfs_name = "2", .name = "Dual port serial" },
+};
+
+static struct mdev_type *mtty_mdev_types[] = {
+	&mtty_types[0].type,
+	&mtty_types[1].type,
+};
+
 static atomic_t mdev_avail_ports = ATOMIC_INIT(MAX_MTTYS);
 
 static const struct file_operations vd_fops = {
···
 	struct mdev_state *mdev_state =
 		container_of(vdev, struct mdev_state, vdev);
 	struct mdev_device *mdev = to_mdev_device(vdev->dev);
-	int nr_ports = mdev_get_type_group_id(mdev) + 1;
+	struct mtty_type *type =
+		container_of(mdev->type, struct mtty_type, type);
 	int avail_ports = atomic_read(&mdev_avail_ports);
 	int ret;
 
 	do {
-		if (avail_ports < nr_ports)
+		if (avail_ports < type->nr_ports)
 			return -ENOSPC;
 	} while (!atomic_try_cmpxchg(&mdev_avail_ports,
-				     &avail_ports, avail_ports - nr_ports));
+				     &avail_ports,
+				     avail_ports - type->nr_ports));
 
-	mdev_state->nr_ports = nr_ports;
+	mdev_state->nr_ports = type->nr_ports;
 	mdev_state->irq_index = -1;
 	mdev_state->s[0].max_fifo_size = MAX_FIFO_SIZE;
 	mdev_state->s[1].max_fifo_size = MAX_FIFO_SIZE;
···
 	return 0;
 
 err_nr_ports:
-	atomic_add(nr_ports, &mdev_avail_ports);
+	atomic_add(type->nr_ports, &mdev_avail_ports);
 	return ret;
 }
 
···
 static ssize_t name_show(struct mdev_type *mtype,
 			 struct mdev_type_attribute *attr, char *buf)
 {
-	static const char *name_str[2] = { "Single port serial",
-					   "Dual port serial" };
+	struct mtty_type *type = container_of(mtype, struct mtty_type, type);
 
-	return sysfs_emit(buf, "%s\n",
-			  name_str[mtype_get_type_group_id(mtype)]);
+	return sysfs_emit(buf, "%s\n", type->name);
 }
 
 static MDEV_TYPE_ATTR_RO(name);
···
 					struct mdev_type_attribute *attr,
 					char *buf)
 {
-	unsigned int ports = mtype_get_type_group_id(mtype) + 1;
+	struct mtty_type *type = container_of(mtype, struct mtty_type, type);
 
-	return sprintf(buf, "%d\n", atomic_read(&mdev_avail_ports) / ports);
+	return sprintf(buf, "%d\n", atomic_read(&mdev_avail_ports) /
+			type->nr_ports);
 }
 
 static MDEV_TYPE_ATTR_RO(available_instances);
···
 
 static MDEV_TYPE_ATTR_RO(device_api);
 
-static struct attribute *mdev_types_attrs[] = {
+static const struct attribute *mdev_types_attrs[] = {
 	&mdev_type_attr_name.attr,
 	&mdev_type_attr_device_api.attr,
 	&mdev_type_attr_available_instances.attr,
-	NULL,
-};
-
-static struct attribute_group mdev_type_group1 = {
-	.name  = "1",
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group mdev_type_group2 = {
-	.name  = "2",
-	.attrs = mdev_types_attrs,
-};
-
-static struct attribute_group *mdev_type_groups[] = {
-	&mdev_type_group1,
-	&mdev_type_group2,
 	NULL,
 };
 
···
 	},
 	.probe = mtty_probe,
 	.remove	= mtty_remove,
-	.supported_type_groups = mdev_type_groups,
+	.types_attrs = mdev_types_attrs,
 };
 
 static void mtty_device_release(struct device *dev)
···
 		goto err_class;
 
 	ret = mdev_register_parent(&mtty_dev.parent, &mtty_dev.dev,
-				   &mtty_driver);
+				   &mtty_driver, mtty_mdev_types,
+				   ARRAY_SIZE(mtty_mdev_types));
 	if (ret)
 		goto err_device;
 	return 0;