Re: [PATCH 09/13] vfio/mdev: consolidate all the device_api sysfs into the core code

[Kirti Wankhede <kwankhede@nvidia.com>]

On 6/14/2022 10:24 AM, Christoph Hellwig wrote:
> From: Jason Gunthorpe <jgg@nvidia.com>
> 
> Every driver just emits a static string, simply feed it through the ops
> and provide a standard sysfs show function.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>

> ---
>   .../driver-api/vfio-mediated-device.rst       |  2 +-
>   drivers/gpu/drm/i915/gvt/kvmgt.c              |  9 +----
>   drivers/s390/cio/vfio_ccw_ops.c               | 11 ++----
>   drivers/s390/crypto/vfio_ap_ops.c             | 10 +-----
>   drivers/vfio/mdev/mdev_driver.c               |  4 ++-
>   drivers/vfio/mdev/mdev_sysfs.c                | 35 +++++++++++++------
>   include/linux/mdev.h                          |  7 ++--
>   samples/vfio-mdev/mbochs.c                    |  9 +----
>   samples/vfio-mdev/mdpy.c                      |  9 +----
>   samples/vfio-mdev/mtty.c                      | 10 +-----
>   10 files changed, 38 insertions(+), 68 deletions(-)
> 
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
> index 27247b3bdcb57..e9913bfb4393b 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -204,7 +204,7 @@ Directories and files under the sysfs for Each Physical Device
>   
>   * device_api
>   
> -  This attribute should show which device API is being created, for example,
> +  This attribute shows which device API is being created, for example,
>     "vfio-pci" for a PCI device.
>   
>   * available_instances
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 136f9c0df48b9..44a418d897377 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -123,12 +123,6 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
>   	return sprintf(buf, "%u\n", type->avail_instance);
>   }
>   
> -static ssize_t device_api_show(struct mdev_type *mtype,
> -			       struct mdev_type_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
> -}
> -
>   static ssize_t description_show(struct mdev_type *mtype,
>   				struct mdev_type_attribute *attr, char *buf)
>   {
> @@ -151,13 +145,11 @@ static ssize_t name_show(struct mdev_type *mtype,
>   }
>   
>   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 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,
> @@ -1587,6 +1579,7 @@ static void intel_vgpu_remove(struct mdev_device *mdev)
>   }
>   
>   static struct mdev_driver intel_vgpu_mdev_driver = {
> +	.device_api	= VFIO_DEVICE_API_PCI_STRING,
>   	.driver = {
>   		.name		= "intel_vgpu_mdev",
>   		.owner		= THIS_MODULE,
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> index 43d53736dfe3c..730d87a96a305 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -77,13 +77,6 @@ static ssize_t name_show(struct mdev_type *mtype,
>   }
>   static MDEV_TYPE_ATTR_RO(name);
>   
> -static ssize_t device_api_show(struct mdev_type *mtype,
> -			       struct mdev_type_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "%s\n", VFIO_DEVICE_API_CCW_STRING);
> -}
> -static MDEV_TYPE_ATTR_RO(device_api);
> -
>   static ssize_t available_instances_show(struct mdev_type *mtype,
>   					struct mdev_type_attribute *attr,
>   					char *buf)
> @@ -96,7 +89,6 @@ static MDEV_TYPE_ATTR_RO(available_instances);
>   
>   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,
>   };
> @@ -636,6 +628,7 @@ static const struct vfio_device_ops vfio_ccw_dev_ops = {
>   };
>   
>   struct mdev_driver vfio_ccw_mdev_driver = {
> +	.device_api = VFIO_DEVICE_API_CCW_STRING,
>   	.driver = {
>   		.name = "vfio_ccw_mdev",
>   		.owner = THIS_MODULE,
> @@ -648,7 +641,7 @@ struct mdev_driver vfio_ccw_mdev_driver = {
>   
>   int vfio_ccw_mdev_reg(struct subchannel *sch)
>   {
> -	sprintf(sch->mdev_type.sysfs_name, "io");
> +	strcat(sch->mdev_type.sysfs_name, "io");
>   	sch->mdev_types[0] = &sch->mdev_type;
>   	return mdev_register_parent(&sch->parent, &sch->dev,
>   				    &vfio_ccw_mdev_driver, sch->mdev_types,
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index ff25858b2ebbe..da21fd60877fb 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -529,17 +529,8 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
>   
>   static MDEV_TYPE_ATTR_RO(available_instances);
>   
> -static ssize_t device_api_show(struct mdev_type *mtype,
> -			       struct mdev_type_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "%s\n", VFIO_DEVICE_API_AP_STRING);
> -}
> -
> -static MDEV_TYPE_ATTR_RO(device_api);
> -
>   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,
>   };
> @@ -1454,6 +1445,7 @@ static const struct vfio_device_ops vfio_ap_matrix_dev_ops = {
>   };
>   
>   static struct mdev_driver vfio_ap_matrix_driver = {
> +	.device_api = VFIO_DEVICE_API_AP_STRING,
>   	.driver = {
>   		.name = "vfio_ap_mdev",
>   		.owner = THIS_MODULE,
> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
> index 5b3c94f4fb13d..60e8b9f6474e8 100644
> --- a/drivers/vfio/mdev/mdev_driver.c
> +++ b/drivers/vfio/mdev/mdev_driver.c
> @@ -55,8 +55,10 @@ struct bus_type mdev_bus_type = {
>    **/
>   int mdev_register_driver(struct mdev_driver *drv)
>   {
> -	if (!drv->types_attrs)
> +	if (!drv->types_attrs || !drv->device_api)
>   		return -EINVAL;
> +
> +	/* initialize common driver fields */
>   	drv->driver.bus = &mdev_bus_type;
>   	return driver_register(&drv->driver);
>   }
> diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
> index dd81b91afcf7d..20763f1aa9f5a 100644
> --- a/drivers/vfio/mdev/mdev_sysfs.c
> +++ b/drivers/vfio/mdev/mdev_sysfs.c
> @@ -72,9 +72,30 @@ static ssize_t create_store(struct mdev_type *mtype,
>   
>   	return count;
>   }
> -
>   static MDEV_TYPE_ATTR_WO(create);
>   
> +static ssize_t device_api_show(struct mdev_type *mtype,
> +			       struct mdev_type_attribute *attr, char *buf)
> +{
> +	return sysfs_emit(buf, "%s\n", mtype->parent->mdev_driver->device_api);
> +}
> +static MDEV_TYPE_ATTR_RO(device_api);
> +
> +static struct attribute *mdev_types_core_attrs[] = {
> +	&mdev_type_attr_create.attr,
> +	&mdev_type_attr_device_api.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group mdev_type_core_group = {
> +	.attrs = mdev_types_core_attrs,
> +};
> +
> +static const struct attribute_group *mdev_type_groups[] = {
> +	&mdev_type_core_group,
> +	NULL,
> +};
> +
>   static void mdev_type_release(struct kobject *kobj)
>   {
>   	struct mdev_type *type = to_mdev_type(kobj);
> @@ -84,8 +105,9 @@ static void mdev_type_release(struct kobject *kobj)
>   }
>   
>   static struct kobj_type mdev_type_ktype = {
> -	.sysfs_ops = &mdev_type_sysfs_ops,
> -	.release = mdev_type_release,
> +	.sysfs_ops	= &mdev_type_sysfs_ops,
> +	.release	= mdev_type_release,
> +	.default_groups	= mdev_type_groups,
>   };
>   
>   int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
> @@ -100,10 +122,6 @@ int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
>   	if (ret)
>   		return ret;
>   
> -	ret = sysfs_create_file(&type->kobj, &mdev_type_attr_create.attr);
> -	if (ret)
> -		goto attr_create_failed;
> -
>   	type->devices_kobj = kobject_create_and_add("devices", &type->kobj);
>   	if (!type->devices_kobj) {
>   		ret = -ENOMEM;
> @@ -118,8 +136,6 @@ int mdev_type_add(struct mdev_parent *parent, struct mdev_type *type)
>   attrs_failed:
>   	kobject_put(type->devices_kobj);
>   attr_devices_failed:
> -	sysfs_remove_file(&type->kobj, &mdev_type_attr_create.attr);
> -attr_create_failed:
>   	kobject_del(&type->kobj);
>   	kobject_put(&type->kobj);
>   	return ret;
> @@ -130,7 +146,6 @@ void mdev_type_remove(struct mdev_type *type)
>   	sysfs_remove_files(&type->kobj, type->parent->mdev_driver->types_attrs);
>   
>   	kobject_put(type->devices_kobj);
> -	sysfs_remove_file(&type->kobj, &mdev_type_attr_create.attr);
>   	kobject_del(&type->kobj);
>   	kobject_put(&type->kobj);
>   }
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index ecf964d34f2ca..81e11e18b3e41 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -61,11 +61,6 @@ struct mdev_type_attribute {
>   			 size_t count);
>   };
>   
> -#define MDEV_TYPE_ATTR(_name, _mode, _show, _store)		\
> -struct mdev_type_attribute mdev_type_attr_##_name =		\
> -	__ATTR(_name, _mode, _show, _store)
> -#define MDEV_TYPE_ATTR_RW(_name) \
> -	struct mdev_type_attribute mdev_type_attr_##_name = __ATTR_RW(_name)
>   #define MDEV_TYPE_ATTR_RO(_name) \
>   	struct mdev_type_attribute mdev_type_attr_##_name = __ATTR_RO(_name)
>   #define MDEV_TYPE_ATTR_WO(_name) \
> @@ -73,12 +68,14 @@ struct mdev_type_attribute mdev_type_attr_##_name =		\
>   
>   /**
>    * struct mdev_driver - Mediated device driver
> + * @device_api:	String to return for the device_api sysfs
>    * @probe: called when new device created
>    * @remove: called when device removed
>    * @types_attrs: attributes to the type kobjects.
>    * @driver: device driver structure
>    **/
>   struct mdev_driver {
> +	const char *device_api;
>   	int (*probe)(struct mdev_device *dev);
>   	void (*remove)(struct mdev_device *dev);
>   	const struct attribute * const *types_attrs;
> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
> index 1069f561cb012..199846f01de92 100644
> --- a/samples/vfio-mdev/mbochs.c
> +++ b/samples/vfio-mdev/mbochs.c
> @@ -1367,17 +1367,9 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
>   }
>   static MDEV_TYPE_ATTR_RO(available_instances);
>   
> -static ssize_t device_api_show(struct mdev_type *mtype,
> -			       struct mdev_type_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
> -}
> -static MDEV_TYPE_ATTR_RO(device_api);
> -
>   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,
>   };
> @@ -1391,6 +1383,7 @@ static const struct vfio_device_ops mbochs_dev_ops = {
>   };
>   
>   static struct mdev_driver mbochs_driver = {
> +	.device_api = VFIO_DEVICE_API_PCI_STRING,
>   	.driver = {
>   		.name = "mbochs",
>   		.owner = THIS_MODULE,
> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
> index 40b1c8a58157c..401a9a622673c 100644
> --- a/samples/vfio-mdev/mdpy.c
> +++ b/samples/vfio-mdev/mdpy.c
> @@ -678,17 +678,9 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
>   }
>   static MDEV_TYPE_ATTR_RO(available_instances);
>   
> -static ssize_t device_api_show(struct mdev_type *mtype,
> -			       struct mdev_type_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
> -}
> -static MDEV_TYPE_ATTR_RO(device_api);
> -
>   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,
>   };
> @@ -701,6 +693,7 @@ static const struct vfio_device_ops mdpy_dev_ops = {
>   };
>   
>   static struct mdev_driver mdpy_driver = {
> +	.device_api = VFIO_DEVICE_API_PCI_STRING,
>   	.driver = {
>   		.name = "mdpy",
>   		.owner = THIS_MODULE,
> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
> index 029a19ef8ce7b..2a470424628af 100644
> --- a/samples/vfio-mdev/mtty.c
> +++ b/samples/vfio-mdev/mtty.c
> @@ -1268,17 +1268,8 @@ static ssize_t available_instances_show(struct mdev_type *mtype,
>   
>   static MDEV_TYPE_ATTR_RO(available_instances);
>   
> -static ssize_t device_api_show(struct mdev_type *mtype,
> -			       struct mdev_type_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
> -}
> -
> -static MDEV_TYPE_ATTR_RO(device_api);
> -
>   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,
>   };
> @@ -1291,6 +1282,7 @@ static const struct vfio_device_ops mtty_dev_ops = {
>   };
>   
>   static struct mdev_driver mtty_driver = {
> +	.device_api = VFIO_DEVICE_API_PCI_STRING,
>   	.driver = {
>   		.name = "mtty",
>   		.owner = THIS_MODULE,