RE: [PATCH v4 1/4] vdpa: Add stop operation

[Eli Cohen]

> From: Eugenio Pérez <eperezma@xxxxxxxxxx>
> Sent: Thursday, May 26, 2022 3:44 PM
> To: Michael S. Tsirkin <mst@xxxxxxxxxx>; kvm@xxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> Jason Wang <jasowang@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx
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> Parav Pandit <parav@xxxxxxxxxx>; Eli Cohen <elic@xxxxxxxxxx>; Dan Carpenter <dan.carpenter@xxxxxxxxxx>; Xie Yongji
> <xieyongji@xxxxxxxxxxxxx>; Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>; Zhang Min <zhang.min9@xxxxxxxxxx>; Wu Zongyong
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> Subject: [PATCH v4 1/4] vdpa: Add stop operation
> 
> This operation is optional: It it's not implemented, backend feature bit
> will not be exposed.
> 
> Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
> ---
>  include/linux/vdpa.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 15af802d41c4..ddfebc4e1e01 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -215,6 +215,11 @@ struct vdpa_map_file {
>   * @reset:			Reset device
>   *				@vdev: vdpa device
>   *				Returns integer: success (0) or error (< 0)
> + * @stop:			Stop or resume the device (optional, but it must
> + *				be implemented if require device stop)
> + *				@vdev: vdpa device
> + *				@stop: stop (true), not stop (false)
> + *				Returns integer: success (0) or error (< 0)

I assume after successful "stop" the device is guaranteed to stop processing descriptors and after resume it may process descriptors?
If that is so, I think it should be clear in the change log.

>   * @get_config_size:		Get the size of the configuration space includes
>   *				fields that are conditional on feature bits.
>   *				@vdev: vdpa device
> @@ -316,6 +321,7 @@ struct vdpa_config_ops {
>  	u8 (*get_status)(struct vdpa_device *vdev);
>  	void (*set_status)(struct vdpa_device *vdev, u8 status);
>  	int (*reset)(struct vdpa_device *vdev);
> +	int (*stop)(struct vdpa_device *vdev, bool stop);
>  	size_t (*get_config_size)(struct vdpa_device *vdev);
>  	void (*get_config)(struct vdpa_device *vdev, unsigned int offset,
>  			   void *buf, unsigned int len);
> --
> 2.31.1