Subject: Re: [PATCH net-next v11 04/12] virtio: Expose object create and destroy API

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 18 Nov 2025 17:14:54 -0500

On Tue, Nov 18, 2025 at 08:38:54AM -0600, Daniel Jurgens wrote:
> Object create and destroy were implemented specifically for dev parts
> device objects. Create general purpose APIs for use by upper layer
> drivers.
> 
> Signed-off-by: Daniel Jurgens <[email-masked]>
> Reviewed-by: Parav Pandit <[email-masked]>
> Reviewed-by: Xuan Zhuo <[email-masked]>
> 
> ---
> v4: Moved this logic from virtio_pci_modern to new file
>     virtio_admin_commands.
> v5: Added missing params, and synced names in comments (Alok Tiwari)
> ---
>  drivers/virtio/virtio_admin_commands.c | 75 ++++++++++++++++++++++++++
>  include/linux/virtio_admin.h           | 44 +++++++++++++++
>  2 files changed, 119 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_admin_commands.c b/drivers/virtio/virtio_admin_commands.c
> index 94751d16b3c4..2b80548ba3bc 100644
> --- a/drivers/virtio/virtio_admin_commands.c
> +++ b/drivers/virtio/virtio_admin_commands.c
> @@ -88,3 +88,78 @@ int virtio_admin_cap_set(struct virtio_device *vdev,
>  	return err;
>  }
>  EXPORT_SYMBOL_GPL(virtio_admin_cap_set);
> +
> +int virtio_admin_obj_create(struct virtio_device *vdev,
> +			    u16 obj_type,
> +			    u32 obj_id,
> +			    u16 group_type,
> +			    u64 group_member_id,
> +			    const void *obj_specific_data,
> +			    size_t obj_specific_data_size)
> +{
> +	size_t data_size = sizeof(struct virtio_admin_cmd_resource_obj_create_data);
> +	struct virtio_admin_cmd_resource_obj_create_data *obj_create_data;
> +	struct virtio_admin_cmd cmd = {};
> +	struct scatterlist data_sg;
> +	void *data;
> +	int err;
> +
> +	if (!vdev->config->admin_cmd_exec)
> +		return -EOPNOTSUPP;
> +
> +	data_size += obj_specific_data_size;
> +	data = kzalloc(data_size, GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	obj_create_data = data;
> +	obj_create_data->hdr.type = cpu_to_le16(obj_type);
> +	obj_create_data->hdr.id = cpu_to_le32(obj_id);
> +	memcpy(obj_create_data->resource_obj_specific_data, obj_specific_data,
> +	       obj_specific_data_size);
> +	sg_init_one(&data_sg, data, data_size);
> +
> +	cmd.opcode = cpu_to_le16(VIRTIO_ADMIN_CMD_RESOURCE_OBJ_CREATE);
> +	cmd.group_type = cpu_to_le16(group_type);
> +	cmd.group_member_id = cpu_to_le64(group_member_id);
> +	cmd.data_sg = &data_sg;
> +
> +	err = vdev->config->admin_cmd_exec(vdev, &cmd);
> +	kfree(data);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(virtio_admin_obj_create);
> +
> +int virtio_admin_obj_destroy(struct virtio_device *vdev,
> +			     u16 obj_type,
> +			     u32 obj_id,
> +			     u16 group_type,
> +			     u64 group_member_id)

what's the point of making it int when none of the callers
check the return type?

> +{
> +	struct virtio_admin_cmd_resource_obj_cmd_hdr *data;
> +	struct virtio_admin_cmd cmd = {};
> +	struct scatterlist data_sg;
> +	int err;
> +
> +	if (!vdev->config->admin_cmd_exec)
> +		return -EOPNOTSUPP;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->type = cpu_to_le16(obj_type);
> +	data->id = cpu_to_le32(obj_id);
> +	sg_init_one(&data_sg, data, sizeof(*data));
> +	cmd.opcode = cpu_to_le16(VIRTIO_ADMIN_CMD_RESOURCE_OBJ_DESTROY);
> +	cmd.group_type = cpu_to_le16(group_type);
> +	cmd.group_member_id = cpu_to_le64(group_member_id);
> +	cmd.data_sg = &data_sg;
> +
> +	err = vdev->config->admin_cmd_exec(vdev, &cmd);
> +	kfree(data);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(virtio_admin_obj_destroy);
> diff --git a/include/linux/virtio_admin.h b/include/linux/virtio_admin.h
> index 36df97b6487a..039b996f73ec 100644
> --- a/include/linux/virtio_admin.h
> +++ b/include/linux/virtio_admin.h
> @@ -77,4 +77,48 @@ int virtio_admin_cap_set(struct virtio_device *vdev,
>  			 const void *caps,
>  			 size_t cap_size);
>  
> +/**
> + * virtio_admin_obj_create - Create an object on a virtio device
> + * @vdev: the virtio device
> + * @obj_type: type of object to create
> + * @obj_id: ID for the new object
> + * @group_type: administrative group type for the operation
> + * @group_member_id: member identifier within the administrative group
> + * @obj_specific_data: object-specific data for creation
> + * @obj_specific_data_size: size of the object-specific data in bytes
> + *
> + * Creates a new object on the virtio device with the specified type and ID.
> + * The object may require object-specific data for proper initialization.
> + *
> + * Return: 0 on success, -EOPNOTSUPP if the device doesn't support admin
> + * operations or object creation, or a negative error code on other failures.
> + */
> +int virtio_admin_obj_create(struct virtio_device *vdev,
> +			    u16 obj_type,
> +			    u32 obj_id,
> +			    u16 group_type,
> +			    u64 group_member_id,
> +			    const void *obj_specific_data,
> +			    size_t obj_specific_data_size);
> +
> +/**
> + * virtio_admin_obj_destroy - Destroy an object on a virtio device
> + * @vdev: the virtio device
> + * @obj_type: type of object to destroy
> + * @obj_id: ID of the object to destroy
> + * @group_type: administrative group type for the operation
> + * @group_member_id: member identifier within the administrative group
> + *
> + * Destroys an existing object on the virtio device with the specified type
> + * and ID.
> + *
> + * Return: 0 on success, -EOPNOTSUPP if the device doesn't support admin
> + * operations or object destruction, or a negative error code on other failures.
> + */
> +int virtio_admin_obj_destroy(struct virtio_device *vdev,
> +			     u16 obj_type,
> +			     u32 obj_id,
> +			     u16 group_type,
> +			     u64 group_member_id);
> +
>  #endif /* _LINUX_VIRTIO_ADMIN_H */
> -- 
> 2.50.1