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 <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220923092652.100656-6-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

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

@@ -103,7 +103,7 @@ structure to represent a mediated device's driver::
      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

@@ -310,8 +310,8 @@ struct intel_vgpu_config {
 	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;
@@ -339,6 +339,7 @@ struct intel_gvt {
 	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

@@ -117,17 +117,10 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 					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,
@@ -139,12 +132,8 @@ 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"
@@ -158,74 +147,22 @@ static ssize_t description_show(struct mdev_type *mtype,
 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(device_api);
 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)
 {
@@ -1547,16 +1484,11 @@ static const struct attribute_group *intel_vgpu_groups[] = {
 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);
 }
 
@@ -1625,7 +1557,7 @@ static struct mdev_driver intel_vgpu_mdev_driver = {
 	},
 	.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)
@@ -1924,7 +1856,6 @@ static void intel_gvt_clean_device(struct drm_i915_private *i915)
 		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);
 
@@ -2024,20 +1955,15 @@ static int intel_gvt_init_device(struct drm_i915_private *i915)
 
 	intel_gvt_debugfs_init(gvt);
 
-	ret = intel_gvt_init_vgpu_type_groups(gvt);
-	if (ret)
-		goto out_destroy_idle_vgpu;
-
 	ret = mdev_register_parent(&gvt->parent, i915->drm.dev,
-				   &intel_vgpu_mdev_driver);
+				   &intel_vgpu_mdev_driver,
+				   gvt->mdev_types, gvt->num_types);
 	if (ret)
-		goto out_cleanup_vgpu_type_groups;
+		goto out_destroy_idle_vgpu;
 
 	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

@@ -113,13 +113,18 @@ int intel_gvt_init_vgpu_types(struct intel_gvt *gvt)
 	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);
@@ -131,18 +136,24 @@ int intel_gvt_init_vgpu_types(struct intel_gvt *gvt)
 			     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

@@ -202,7 +202,6 @@ static void vfio_ccw_free_private(struct vfio_ccw_private *private)
 	mutex_destroy(&private->io_mutex);
 	kfree(private);
 }
-
 static int vfio_ccw_sch_probe(struct subchannel *sch)
 {
 	struct pmcw *pmcw = &sch->schib.pmcw;
@@ -221,8 +220,11 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
 
 	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

@@ -69,23 +69,13 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 }
 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,
-};
-
 static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev)
 {
 	struct vfio_ccw_private *private =
@@ -646,5 +636,5 @@ struct mdev_driver vfio_ccw_mdev_driver = {
 	},
 	.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

@@ -120,6 +120,8 @@ struct vfio_ccw_private {
 	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

@@ -816,23 +816,13 @@ static ssize_t device_api_show(struct mdev_type *mtype,
 
 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,
-};
-
 #define MDEV_SHARING_ERR "Userspace may not re-assign queue %02lx.%04lx " \
 			 "already assigned to %s"
 
@@ -1817,7 +1807,7 @@ static struct mdev_driver vfio_ap_matrix_driver = {
 	},
 	.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)
@@ -1830,8 +1820,11 @@ 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

@@ -53,6 +53,8 @@ struct ap_matrix_dev {
 	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;