Re: [PATCH] vfio/mdev: Add vfio-mdev device request interface

[Alex Williamson <alex.williamson@redhat.com>]

On Sun, 26 Apr 2020 14:35:42 +0800
Yingtai Xie <xieyingtai@huawei.com> wrote:

> This is setup the same way as vfio-pci to indicate
> userspace that the device should be released.


Is there an in-kernel user?


> Signed-off-by: Yingtai Xie <xieyingtai@huawei.com>
> ---
>  drivers/vfio/mdev/vfio_mdev.c | 10 ++++++++++
>  include/linux/mdev.h          |  4 ++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index 30964a4e0..74695c116 100644
> --- a/drivers/vfio/mdev/vfio_mdev.c
> +++ b/drivers/vfio/mdev/vfio_mdev.c
> @@ -98,6 +98,15 @@ static int vfio_mdev_mmap(void *device_data, struct vm_area_struct *vma)
>  	return parent->ops->mmap(mdev, vma);
>  }
>  
> +static void vfio_mdev_request(void *device_data, unsigned int count)
> +{
> +	struct mdev_device *mdev = device_data;
> +	struct mdev_parent *parent = mdev->parent;
> +
> +	if (likely(!parent->ops->request))
> +		parent->ops->request(mdev, count);
> +}
> +
>  static const struct vfio_device_ops vfio_mdev_dev_ops = {
>  	.name		= "vfio-mdev",
>  	.open		= vfio_mdev_open,
> @@ -106,6 +115,7 @@ static const struct vfio_device_ops vfio_mdev_dev_ops = {
>  	.read		= vfio_mdev_read,
>  	.write		= vfio_mdev_write,
>  	.mmap		= vfio_mdev_mmap,
> +	.request	= vfio_mdev_request,
>  };
>  
>  static int vfio_mdev_probe(struct device *dev)
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 0ce30ca78..1ab0b0b9b 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -72,6 +72,9 @@ struct device *mdev_get_iommu_device(struct device *dev);
>   * @mmap:		mmap callback
>   *			@mdev: mediated device structure
>   *			@vma: vma structure
> + * @request	request callback
> + *			@mdev: mediated device structure
> + *			@count: counter to allow driver to release the device
>   * Parent device that support mediated device should be registered with mdev
>   * module with mdev_parent_ops structure.
>   **/
> @@ -92,6 +95,7 @@ struct mdev_parent_ops {
>  	long	(*ioctl)(struct mdev_device *mdev, unsigned int cmd,
>  			 unsigned long arg);
>  	int	(*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma);
> +	int	(*request)(struct mdev_device *mdev, unsigned int count);
>  };
>  
>  /* interface for exporting mdev supported type attributes */