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From:   Jason Wang <jasowang@redhat.com>
Date:   Wed, 28 Jun 2023 16:13:14 +0800
Message-ID: <CACGkMEtN7pE4FK2-504JC3A1tcfPjy9QejJiTyvXD7nt49KLvA@mail.gmail.com>
Subject: Re: [RFC 4/4] vduse: update the vq_info in ioctl
To:     Cindy Lu <lulu@redhat.com>
Cc:     mst@redhat.com, maxime.coquelin@redhat.com,
        xieyongji@bytedance.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org
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On Wed, Jun 28, 2023 at 3:00=E2=80=AFPM Cindy Lu <lulu@redhat.com> wrote:
>
> From: Your Name <you@example.com>
>
> in VDUSE_VQ_GET_INFO, driver will sync the last_avail_idx
> with reconnect info, I have olny test the split mode, so

Typo, should be "only".

> only use this here, will add more information later
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  drivers/vdpa/vdpa_user/vduse_dev.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/=
vduse_dev.c
> index 3df1256eccb4..b8e453eac0ce 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -141,6 +141,11 @@ static u32 allowed_device_id[] =3D {
>         VIRTIO_ID_NET,
>  };
>
> +struct vhost_reconnect_vring {
> +       uint16_t last_avail_idx;
> +       bool avail_wrap_counter;
> +};

Should this belong to uAPI?

> +
>  static inline struct vduse_dev *vdpa_to_vduse(struct vdpa_device *vdpa)
>  {
>         struct vduse_vdpa *vdev =3D container_of(vdpa, struct vduse_vdpa,=
 vdpa);
> @@ -1176,6 +1181,17 @@ static long vduse_dev_ioctl(struct file *file, uns=
igned int cmd,
>                                 vq->state.split.avail_index;
>
>                 vq_info.ready =3D vq->ready;
> +               struct vdpa_reconnect_info *area;
> +
> +               area =3D &dev->reconnect_info[index];
> +               struct vhost_reconnect_vring *log_reconnect;
> +
> +               log_reconnect =3D (struct vhost_reconnect_vring *)area->v=
addr;

What if userspace doesn't do mmap()?

Thanks

> +               if (log_reconnect->last_avail_idx !=3D
> +                   vq_info.split.avail_index) {
> +                       vq_info.split.avail_index =3D
> +                               log_reconnect->last_avail_idx;
> +               }
>
>                 ret =3D -EFAULT;
>                 if (copy_to_user(argp, &vq_info, sizeof(vq_info)))
> --
> 2.34.3
>