[PATCH 3/8] vfio/mdev: simplify mdev_type handling
Kirti Wankhede
kwankhede at nvidia.com
Mon Jun 6 19:22:49 UTC 2022
<snip...>
> static ssize_t remove_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 327ce3e5c6b5f..cbb53dcd20d9d 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -23,12 +23,17 @@ struct mdev_device {
> bool active;
> };
>
> +struct mdev_type {
> + struct kobject kobj;
> + struct kobject *devices_kobj;
> + struct mdev_parent *parent;
> +};
> +
> /* 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;
> };
> @@ -38,8 +43,11 @@ 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);
> +int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type,
> + const char *name, const struct attribute * const *attrs);
> +void mdev_type_remove(struct mdev_type *type,
> + const struct attribute * const *attrs);
> +
> struct device *mtype_get_parent_dev(struct mdev_type *mtype);
>
> /* interface for exporting mdev supported type attributes */
> @@ -66,15 +74,12 @@ struct mdev_type_attribute mdev_type_attr_##_name = \
> * 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.
> * @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;
> struct device_driver driver;
> };
mdev_type should be part of mdev_parent, separating it from mdev_parent
could result in more errors while using mdev framework. Similarly it
should be added as part of mdev_register_device. Below adding types is
separated from mdev_register_device which is more error prone. What if
driver registering to mdev doesn't add mdev_types? - mdev framework is
un-usable in that case. We had kept it together with mdev registration
so that mdev_types should be mandatory to be defined by driver during
registration. How would you mandate mdev_type by such separation?
Thanks,
Kirti
>
> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
> index f0967a81eabe7..32fd6f385fafd 100644
> --- a/samples/vfio-mdev/mbochs.c
> +++ b/samples/vfio-mdev/mbochs.c
> @@ -100,23 +100,28 @@ 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 *fname;
> const char *name;
> u32 mbytes;
> u32 max_x;
> u32 max_y;
> } mbochs_types[] = {
> {
> + .fname = MBOCHS_TYPE_1,
> .name = MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_1,
> .mbytes = 4,
> .max_x = 800,
> .max_y = 600,
> }, {
> + .fname = MBOCHS_TYPE_2,
> .name = MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_2,
> .mbytes = 16,
> .max_x = 1920,
> .max_y = 1440,
> }, {
> + .fname = MBOCHS_TYPE_3,
> .name = MBOCHS_CLASS_NAME "-" MBOCHS_TYPE_3,
> .mbytes = 64,
> .max_x = 0,
> @@ -509,8 +514,8 @@ static int mbochs_reset(struct mdev_state *mdev_state)
> static int mbochs_probe(struct mdev_device *mdev)
> {
> int avail_mbytes = atomic_read(&mbochs_avail_mbytes);
> - 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);
> struct device *dev = mdev_dev(mdev);
> struct mdev_state *mdev_state;
> int ret = -ENOMEM;
> @@ -1329,8 +1334,8 @@ 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);
> }
> @@ -1339,8 +1344,8 @@ 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);
> @@ -1351,8 +1356,8 @@ 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);
> @@ -1366,7 +1371,7 @@ 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,
> @@ -1374,28 +1379,6 @@ 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,
> .read = mbochs_read,
> @@ -1413,7 +1396,6 @@ static struct mdev_driver mbochs_driver = {
> },
> .probe = mbochs_probe,
> .remove = mbochs_remove,
> - .supported_type_groups = mdev_type_groups,
> };
>
> static const struct file_operations vd_fops = {
> @@ -1427,7 +1409,7 @@ static void mbochs_device_release(struct device *dev)
>
> static int __init mbochs_dev_init(void)
> {
> - int ret = 0;
> + int i, ret = 0;
>
> atomic_set(&mbochs_avail_mbytes, max_mbytes);
>
> @@ -1461,9 +1443,19 @@ static int __init mbochs_dev_init(void)
> ret = mdev_register_parent(&mbochs_parent, &mbochs_dev, &mbochs_driver);
> if (ret)
> goto err_device;
> + for (i = 0; i < ARRAY_SIZE(mbochs_types); i++) {
> + ret = mdev_type_add(&mbochs_parent, &mbochs_types[i].type,
> + mbochs_types[i].fname, mdev_types_attrs);
> + if (ret)
> + goto err_types;
> + }
>
> return 0;
>
> +err_types:
> + while (--i >= 0)
> + mdev_type_remove(&mbochs_types[i].type, mdev_types_attrs);
> + mdev_unregister_parent(&mbochs_parent);
> err_device:
> device_unregister(&mbochs_dev);
> err_class:
> @@ -1478,7 +1470,11 @@ static int __init mbochs_dev_init(void)
>
> static void __exit mbochs_dev_exit(void)
> {
> + int i;
> +
> mbochs_dev.bus = NULL;
> + for (i = 0; i < ARRAY_SIZE(mbochs_types); i++)
> + mdev_type_remove(&mbochs_types[i].type, mdev_types_attrs);
> mdev_unregister_parent(&mbochs_parent);
>
> device_unregister(&mbochs_dev);
> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
> index 8ab88a1d149cb..a6aa7f6f97095 100644
> --- a/samples/vfio-mdev/mdpy.c
> +++ b/samples/vfio-mdev/mdpy.c
> @@ -52,7 +52,9 @@ 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 *fname;
> const char *name;
> u32 format;
> u32 bytepp;
> @@ -60,18 +62,21 @@ static const struct mdpy_type {
> u32 height;
> } mdpy_types[] = {
> {
> + .fname = MDPY_TYPE_1,
> .name = MDPY_CLASS_NAME "-" MDPY_TYPE_1,
> .format = DRM_FORMAT_XRGB8888,
> .bytepp = 4,
> .width = 640,
> .height = 480,
> }, {
> + .fname = MDPY_TYPE_2,
> .name = MDPY_CLASS_NAME "-" MDPY_TYPE_2,
> .format = DRM_FORMAT_XRGB8888,
> .bytepp = 4,
> .width = 1024,
> .height = 768,
> }, {
> + .fname = MDPY_TYPE_3,
> .name = MDPY_CLASS_NAME "-" MDPY_TYPE_3,
> .format = DRM_FORMAT_XRGB8888,
> .bytepp = 4,
> @@ -220,7 +225,7 @@ static int mdpy_reset(struct mdev_state *mdev_state)
> static int mdpy_probe(struct mdev_device *mdev)
> {
> const struct mdpy_type *type =
> - &mdpy_types[mdev_get_type_group_id(mdev)];
> + container_of(mdev->type, struct mdpy_type, type);
> struct device *dev = mdev_dev(mdev);
> struct mdev_state *mdev_state;
> u32 fbsize;
> @@ -645,8 +650,7 @@ 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);
> }
> @@ -655,8 +659,7 @@ 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);
> @@ -678,7 +681,7 @@ 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,
> @@ -686,28 +689,6 @@ 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 = {
> .read = mdpy_read,
> .write = mdpy_write,
> @@ -724,7 +705,6 @@ static struct mdev_driver mdpy_driver = {
> },
> .probe = mdpy_probe,
> .remove = mdpy_remove,
> - .supported_type_groups = mdev_type_groups,
> };
>
> static const struct file_operations vd_fops = {
> @@ -738,7 +718,7 @@ static void mdpy_device_release(struct device *dev)
>
> static int __init mdpy_dev_init(void)
> {
> - int ret = 0;
> + int i, ret = 0;
>
> ret = alloc_chrdev_region(&mdpy_devt, 0, MINORMASK + 1, MDPY_NAME);
> if (ret < 0) {
> @@ -770,9 +750,19 @@ static int __init mdpy_dev_init(void)
> ret = mdev_register_parent(&mdpy_parent, &mdpy_dev, &mdpy_driver);
> if (ret)
> goto err_device;
> + for (i = 0; i < ARRAY_SIZE(mdpy_types); i++) {
> + ret = mdev_type_add(&mdpy_parent, &mdpy_types[i].type,
> + mdpy_types[i].fname, mdev_types_attrs);
> + if (ret)
> + goto err_types;
> + }
>
> return 0;
>
> +err_types:
> + while (--i >= 0)
> + mdev_type_remove(&mdpy_types[i].type, mdev_types_attrs);
> + mdev_unregister_parent(&mdpy_parent);
> err_device:
> device_unregister(&mdpy_dev);
> err_class:
> @@ -787,7 +777,11 @@ static int __init mdpy_dev_init(void)
>
> static void __exit mdpy_dev_exit(void)
> {
> + int i;
> +
> mdpy_dev.bus = NULL;
> + for (i = 0; i < ARRAY_SIZE(mdpy_types); i++)
> + mdev_type_remove(&mdpy_types[i].type, mdev_types_attrs);
> mdev_unregister_parent(&mdpy_parent);
>
> device_unregister(&mdpy_dev);
> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
> index 20136def93fdb..28c0811cf2312 100644
> --- a/samples/vfio-mdev/mtty.c
> +++ b/samples/vfio-mdev/mtty.c
> @@ -145,6 +145,16 @@ struct mdev_state {
> int nr_ports;
> };
>
> +static struct mtty_type {
> + struct mdev_type type;
> + int nr_ports;
> + const char *fname;
> + const char *name;
> +} mtty_types[2] = {
> + { .nr_ports = 1, .fname = "1", .name = "Single port serial" },
> + { .nr_ports = 2, .fname = "2", .name = "Dual port serial" },
> +};
> +
> static atomic_t mdev_avail_ports = ATOMIC_INIT(MAX_MTTYS);
>
> static const struct file_operations vd_fops = {
> @@ -706,16 +716,18 @@ static ssize_t mdev_access(struct mdev_state *mdev_state, u8 *buf, size_t count,
>
> static int mtty_probe(struct mdev_device *mdev)
> {
> + struct mtty_type *type =
> + container_of(mdev->type, struct mtty_type, type);
> struct mdev_state *mdev_state;
> - int nr_ports = mdev_get_type_group_id(mdev) + 1;
> 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 = kzalloc(sizeof(struct mdev_state), GFP_KERNEL);
> if (mdev_state == NULL) {
> @@ -725,13 +737,13 @@ static int mtty_probe(struct mdev_device *mdev)
>
> vfio_init_group_dev(&mdev_state->vdev, &mdev->dev, &mtty_dev_ops);
>
> - 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;
> mutex_init(&mdev_state->rxtx_lock);
> - mdev_state->vconfig = kzalloc(MTTY_CONFIG_SPACE_SIZE, GFP_KERNEL);
>
> + mdev_state->vconfig = kzalloc(MTTY_CONFIG_SPACE_SIZE, GFP_KERNEL);
> if (mdev_state->vconfig == NULL) {
> ret = -ENOMEM;
> goto err_state;
> @@ -754,7 +766,7 @@ static int mtty_probe(struct mdev_device *mdev)
> vfio_uninit_group_dev(&mdev_state->vdev);
> kfree(mdev_state);
> err_nr_ports:
> - atomic_add(nr_ports, &mdev_avail_ports);
> + atomic_add(type->nr_ports, &mdev_avail_ports);
> return ret;
> }
>
> @@ -1235,11 +1247,9 @@ 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);
> @@ -1248,9 +1258,10 @@ 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);
> @@ -1263,29 +1274,13 @@ 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",
> .read = mtty_read,
> @@ -1302,7 +1297,6 @@ static struct mdev_driver mtty_driver = {
> },
> .probe = mtty_probe,
> .remove = mtty_remove,
> - .supported_type_groups = mdev_type_groups,
> };
>
> static void mtty_device_release(struct device *dev)
> @@ -1312,7 +1306,7 @@ static void mtty_device_release(struct device *dev)
>
> static int __init mtty_dev_init(void)
> {
> - int ret = 0;
> + int i, ret = 0;
>
> pr_info("mtty_dev: %s\n", __func__);
>
> @@ -1357,8 +1351,19 @@ static int __init mtty_dev_init(void)
> &mtty_driver);
> if (ret)
> goto err_device;
> + for (i = 0; i < ARRAY_SIZE(mtty_types); i++) {
> + ret = mdev_type_add(&mtty_dev.parent, &mtty_types[i].type,
> + mtty_types[i].fname, mdev_types_attrs);
> + if (ret)
> + goto err_types;
> + }
> +
> return 0;
>
> +err_types:
> + while (--i >= 0)
> + mdev_type_remove(&mtty_types[i].type, mdev_types_attrs);
> + mdev_unregister_parent(&mtty_dev.parent);
> err_device:
> device_unregister(&mtty_dev.dev);
> err_class:
> @@ -1373,7 +1378,11 @@ static int __init mtty_dev_init(void)
>
> static void __exit mtty_dev_exit(void)
> {
> + int i;
> +
> mtty_dev.dev.bus = NULL;
> + for (i = 0; i < ARRAY_SIZE(mtty_types); i++)
> + mdev_type_remove(&mtty_types[i].type, mdev_types_attrs);
> mdev_unregister_parent(&mtty_dev.parent);
>
> device_unregister(&mtty_dev.dev);
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