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>

3 files changed, 72 insertions, 95 deletions

diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index 2c4791abbc3d..4d0839cb5194 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -99,23 +99,27 @@ MODULE_PARM_DESC(mem, "megabytes available to " MBOCHS_NAME " devices");
 #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,
@@ -123,6 +127,11 @@ static const struct mbochs_type {
 	},
 };
 
+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;
@@ -510,8 +519,8 @@ static int mbochs_init_dev(struct vfio_device *vdev)
 	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;
 
@@ -1345,8 +1354,8 @@ static const struct attribute_group *mdev_dev_groups[] = {
 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);
 }
@@ -1355,8 +1364,8 @@ static MDEV_TYPE_ATTR_RO(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);
@@ -1367,8 +1376,8 @@ static ssize_t available_instances_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);
 	int count = atomic_read(&mbochs_avail_mbytes) / type->mbytes;
 
 	return sprintf(buf, "%d\n", count);
@@ -1382,7 +1391,7 @@ static ssize_t device_api_show(struct mdev_type *mtype,
 }
 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,
@@ -1390,28 +1399,6 @@ static struct attribute *mdev_types_attrs[] = {
 	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,
-};
-
 static const struct vfio_device_ops mbochs_dev_ops = {
 	.close_device = mbochs_close_device,
 	.init = mbochs_init_dev,
@@ -1431,7 +1418,7 @@ static struct mdev_driver mbochs_driver = {
 	},
 	.probe = mbochs_probe,
 	.remove	= mbochs_remove,
-	.supported_type_groups = mdev_type_groups,
+	.types_attrs = mdev_types_attrs,
 };
 
 static const struct file_operations vd_fops = {
@@ -1476,7 +1463,9 @@ static int __init mbochs_dev_init(void)
 	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;
 
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index 01f345430b97..4a341f4849e7 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -51,7 +51,8 @@ MODULE_PARM_DESC(count, "number of " MDPY_NAME " devices");
 #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;
@@ -59,18 +60,21 @@ static const struct mdpy_type {
 	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,
@@ -79,6 +83,12 @@ static const struct mdpy_type {
 	},
 };
 
+static struct mdev_type *mdpy_mdev_types[] = {
+	&mdpy_types[0].type,
+	&mdpy_types[1].type,
+	&mdpy_types[2].type,
+};
+
 static dev_t		mdpy_devt;
 static struct class	*mdpy_class;
 static struct cdev	mdpy_cdev;
@@ -222,7 +232,7 @@ static int mdpy_init_dev(struct vfio_device *vdev)
 		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;
 
@@ -655,8 +665,7 @@ static const struct attribute_group *mdev_dev_groups[] = {
 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);
 }
@@ -665,8 +674,7 @@ static MDEV_TYPE_ATTR_RO(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);
@@ -688,7 +696,7 @@ static ssize_t device_api_show(struct mdev_type *mtype,
 }
 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,
@@ -696,28 +704,6 @@ static struct attribute *mdev_types_attrs[] = {
 	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,
-};
-
 static const struct vfio_device_ops mdpy_dev_ops = {
 	.init = mdpy_init_dev,
 	.release = mdpy_release_dev,
@@ -736,7 +722,7 @@ static struct mdev_driver mdpy_driver = {
 	},
 	.probe = mdpy_probe,
 	.remove	= mdpy_remove,
-	.supported_type_groups = mdev_type_groups,
+	.types_attrs = mdev_types_attrs,
 };
 
 static const struct file_operations vd_fops = {
@@ -779,7 +765,9 @@ static int __init mdpy_dev_init(void)
 	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;
 
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index e80baac51381..814a7f98738a 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -143,6 +143,20 @@ struct mdev_state {
 	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 = {
@@ -707,17 +721,19 @@ static int mtty_init_dev(struct vfio_device *vdev)
 	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;
@@ -735,7 +751,7 @@ static int mtty_init_dev(struct vfio_device *vdev)
 	return 0;
 
 err_nr_ports:
-	atomic_add(nr_ports, &mdev_avail_ports);
+	atomic_add(type->nr_ports, &mdev_avail_ports);
 	return ret;
 }
 
@@ -1242,11 +1258,9 @@ static const struct attribute_group *mdev_dev_groups[] = {
 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);
@@ -1255,9 +1269,10 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
 					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);
@@ -1270,29 +1285,13 @@ static ssize_t device_api_show(struct mdev_type *mtype,
 
 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,
-};
-
 static const struct vfio_device_ops mtty_dev_ops = {
 	.name = "vfio-mtty",
 	.init = mtty_init_dev,
@@ -1311,7 +1310,7 @@ static struct mdev_driver mtty_driver = {
 	},
 	.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)
@@ -1363,7 +1362,8 @@ static int __init mtty_dev_init(void)
 		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;