Re: [PATCH 3/4] vhost-vdpa: uAPI to stop the device

[Martin Habets]

On Fri, May 20, 2022 at 07:23:24PM +0200, Eugenio Pérez wrote:
> The ioctl adds support for stop the device from userspace.
> 
> Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
> ---
>  drivers/vhost/vdpa.c       | 18 ++++++++++++++++++
>  include/uapi/linux/vhost.h |  3 +++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index a325bc259afb..da4a8c709bc1 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -478,6 +478,21 @@ static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
>  	return 0;
>  }
>  
> +static long vhost_vdpa_stop(struct vhost_vdpa *v, u32 __user *argp)
> +{
> +	struct vdpa_device *vdpa = v->vdpa;
> +	const struct vdpa_config_ops *ops = vdpa->config;
> +	int stop;
> +
> +	if (!ops->stop)
> +		return -EOPNOTSUPP;
> +
> +	if (copy_to_user(argp, &stop, sizeof(stop)))

You want to use copy_from_user() here.

Martin

> +		return -EFAULT;
> +
> +	return ops->stop(vdpa, stop);
> +}
> +
>  static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
>  				   void __user *argp)
>  {
> @@ -649,6 +664,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
>  	case VHOST_VDPA_GET_VQS_COUNT:
>  		r = vhost_vdpa_get_vqs_count(v, argp);
>  		break;
> +	case VHOST_STOP:
> +		r = vhost_vdpa_stop(v, argp);
> +		break;
>  	default:
>  		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
>  		if (r == -ENOIOCTLCMD)
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index cab645d4a645..e7526968ab0c 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -171,4 +171,7 @@
>  #define VHOST_VDPA_SET_GROUP_ASID	_IOW(VHOST_VIRTIO, 0x7C, \
>  					     struct vhost_vring_state)
>  
> +/* Stop or resume a device so it does not process virtqueue requests anymore */
> +#define VHOST_STOP			_IOW(VHOST_VIRTIO, 0x7D, int)
> +
>  #endif
> -- 
> 2.27.0