Re: [PATCH v2 3/6] vhost-net: vhost-user: update vhost_net_virtqueue_reset()

[Xuan Zhuo]

On Wed, 14 Sep 2022 11:13:29 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/9/12 11:10, Kangjie Xu 写道:
> > Update vhost_net_virtqueue_reset() for vhost-user scenario.
> >
> > In order to reuse some functions, we process the idx for
> > vhost-user scenario because vhost_get_vq_index behave
> > differently for vhost-user.
> >
> > Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >   hw/net/vhost_net.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> > index ea896ea75b..25e5665489 100644
> > --- a/hw/net/vhost_net.c
> > +++ b/hw/net/vhost_net.c
> > @@ -545,6 +545,9 @@ void vhost_net_virtqueue_reset(VirtIODevice *vdev, 
> > NetClientState *nc,
> >       assert(vhost_ops);
> >
> >       idx = vhost_ops->vhost_get_vq_index(&net->dev, vq_index);
> > +    if (net->nc->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
> > +        idx -= net->dev.vq_index;
> > +    }
>
>
> This looks tricky. Any reason we can't simply use vq_index for both
> vhost-user and vhost-net?


static int vhost_user_get_vq_index(struct vhost_dev *dev, int idx)
{
    assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);

    return idx;
}


static int vhost_kernel_get_vq_index(struct vhost_dev *dev, int idx)
{
    assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);

    return idx - dev->vq_index;
}

The implementation of these two callbacks is different. The structure of the two
scenarios is different. We may need to do some optimizations in the future.

Thanks.


>
> Thanks
>
>
> >
> >       if (net->nc->info->type == NET_CLIENT_DRIVER_TAP) {
> >           file.index = idx;
>