linux-kernel - Re: [PATCH vhost v4 07/15] vdpa: Block vq address change in DRIVER

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Message-ID: <CAJaqyWet3m8HmHRTJNshQgCn0jqyrO476j0Z-rwwqyDNj4B66w@mail.gmail.com>
Date: Wed, 20 Dec 2023 17:31:01 +0100
From: Eugenio Perez Martin <eperezma@...hat.com>
To: Dragos Tatulea <dtatulea@...dia.com>
Cc: "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Si-Wei Liu <si-wei.liu@...cle.com>, Saeed Mahameed <saeedm@...dia.com>, 
	Leon Romanovsky <leon@...nel.org>, virtualization@...ts.linux-foundation.org, 
	Gal Pressman <gal@...dia.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Parav Pandit <parav@...dia.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: Re: [PATCH vhost v4 07/15] vdpa: Block vq address change in DRIVER_OK
 unless device supports it

On Tue, Dec 19, 2023 at 7:09 PM Dragos Tatulea <dtatulea@...dia.com> wrote:
>
> Virtqueue address change during DRIVE_OK is not supported by the virtio
> standard. Allow this op in DRIVER_OK only for devices that support
> changing the address during DRIVER_OK if the device is suspended.
>
> Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
> Suggested-by: Eugenio Pérez <eperezma@...hat.com>

Acked-by: Eugenio Pérez <eperezma@...hat.com>

> ---
>  drivers/vhost/vdpa.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 00b4fa8e89f2..6bfa3391935a 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -625,6 +625,29 @@ static long vhost_vdpa_resume(struct vhost_vdpa *v)
>         return ret;
>  }
>
> +static bool vhost_vdpa_vq_config_allowed(struct vhost_vdpa *v, unsigned int cmd)
> +{
> +       struct vdpa_device *vdpa = v->vdpa;
> +       const struct vdpa_config_ops *ops = vdpa->config;
> +       int feature;
> +
> +       if (!(ops->get_status(vdpa) & VIRTIO_CONFIG_S_DRIVER_OK))
> +               return true;
> +
> +       if (!v->suspended)
> +               return false;
> +
> +       switch (cmd) {
> +       case VHOST_SET_VRING_ADDR:
> +               feature = VHOST_BACKEND_F_CHANGEABLE_VQ_ADDR_IN_SUSPEND;
> +               break;
> +       default:
> +               return false;
> +       }
> +
> +       return v->vdev.vqs && vhost_backend_has_feature(v->vdev.vqs[0], feature);
> +}
> +
>  static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
>                                    void __user *argp)
>  {
> @@ -703,6 +726,9 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
>
>         switch (cmd) {
>         case VHOST_SET_VRING_ADDR:
> +               if (!vhost_vdpa_vq_config_allowed(v, cmd))
> +                       return -EOPNOTSUPP;
> +
>                 if (ops->set_vq_address(vdpa, idx,
>                                         (u64)(uintptr_t)vq->desc,
>                                         (u64)(uintptr_t)vq->avail,
> --
> 2.43.0
>