Re: [RFC v2 3/4] vduse: update the vq_info in ioctl

[Maxime Coquelin]

On 9/12/23 09:39, Jason Wang wrote:
> On Tue, Sep 12, 2023 at 11:00 AM Cindy Lu <lulu@xxxxxxxxxx> wrote:
> > In VDUSE_VQ_GET_INFO, the driver will sync the last_avail_idx
> > with reconnect info, After mapping the reconnect pages to userspace
> > The userspace App will update the reconnect_time in
> > struct vhost_reconnect_vring, If this is not 0 then it means this
> > vq is reconnected and will update the last_avail_idx
> >
> > Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
> > ---
> >   drivers/vdpa/vdpa_user/vduse_dev.c | 13 +++++++++++++
> >   include/uapi/linux/vduse.h         |  6 ++++++
> >   2 files changed, 19 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index 2c69f4004a6e..680b23dbdde2 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -1221,6 +1221,8 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
> >                  struct vduse_vq_info vq_info;
> >                  struct vduse_virtqueue *vq;
> >                  u32 index;
> > +               struct vdpa_reconnect_info *area;
> > +               struct vhost_reconnect_vring *vq_reconnect;
> >
> >                  ret = -EFAULT;
> >                  if (copy_from_user(&vq_info, argp, sizeof(vq_info)))
> > @@ -1252,6 +1254,17 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
> >
> >                  vq_info.ready = vq->ready;
> >
> > +               area = &vq->reconnect_info;
> > +
> > +               vq_reconnect = (struct vhost_reconnect_vring *)area->vaddr;
> > +               /*check if the vq is reconnect, if yes then update the last_avail_idx*/
> > +               if ((vq_reconnect->last_avail_idx !=
> > +                    vq_info.split.avail_index) &&
> > +                   (vq_reconnect->reconnect_time != 0)) {
> > +                       vq_info.split.avail_index =
> > +                               vq_reconnect->last_avail_idx;
> > +               }
> > +
> >                  ret = -EFAULT;
> >                  if (copy_to_user(argp, &vq_info, sizeof(vq_info)))
> >                          break;
> > diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
> > index 11bd48c72c6c..d585425803fd 100644
> > --- a/include/uapi/linux/vduse.h
> > +++ b/include/uapi/linux/vduse.h
> > @@ -350,4 +350,10 @@ struct vduse_dev_response {
> >          };
> >   };
> >
> > +struct vhost_reconnect_vring {
> > +       __u16 reconnect_time;
> > +       __u16 last_avail_idx;
> > +       _Bool avail_wrap_counter;
>
> Please add a comment for each field.
>
> And I never saw _Bool is used in uapi before, maybe it's better to
> pack it with last_avail_idx into a __u32.

Better as two distincts __u16 IMHO.

Thanks,
Maxime

> Btw, do we need to track inflight descriptors as well?
>
> Thanks
>
> > +};
> > +
> >   #endif /* _UAPI_VDUSE_H_ */
> > --
> > 2.34.3