Re: [PATCH v3 10/15] vhost-net: vhost-kernel: introduce vhost_net_virtqueue_reset()

[Jason Wang <jasowang@redhat.com>]

在 2022/8/25 16:08, Kangjie Xu 写道:
> Introduce vhost_virtqueue_reset(), which can reset the specific
> virtqueue in the device. Then it will unmap vrings and the desc
> of the virtqueue.
>
> Here we do not reuse the vhost_net_stop_one() or vhost_dev_stop(),
> because they work at queue pair level. We do not use
> vhost_virtqueue_stop() because it may stop the device in the
> backend.


So I think this is not true at least for vhost-net kernel baceknd.


>
> This patch only considers the case of vhost-kernel, when
> NetClientDriver is NET_CLIENT_DRIVER_TAP.
>
> Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>   hw/net/vhost_net.c      | 22 ++++++++++++++++++++++
>   include/net/vhost_net.h |  2 ++
>   2 files changed, 24 insertions(+)
>
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index ccac5b7a64..be51be98b3 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -514,3 +514,25 @@ int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
>   
>       return vhost_ops->vhost_net_set_mtu(&net->dev, mtu);
>   }
> +
> +void vhost_net_virtqueue_reset(VirtIODevice *vdev, NetClientState *nc,
> +                               int vq_index)
> +{
> +    VHostNetState *net = get_vhost_net(nc->peer);
> +    const VhostOps *vhost_ops = net->dev.vhost_ops;
> +    struct vhost_vring_file file = { .fd = -1 };
> +    int idx;
> +
> +    /* should only be called after backend is connected */
> +    assert(vhost_ops);
> +
> +    idx = vhost_ops->vhost_get_vq_index(&net->dev, vq_index);
> +
> +    if (net->nc->info->type == NET_CLIENT_DRIVER_TAP) {
> +        file.index = idx;
> +        int r = vhost_net_set_backend(&net->dev, &file);
> +        assert(r >= 0);
> +    }


Do we need to reset e.g last_avail_idx here?

Thanks


> +
> +    vhost_virtqueue_unmap(&net->dev, vdev, net->dev.vqs + idx, idx);
> +}
> diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
> index 387e913e4e..85d85a4957 100644
> --- a/include/net/vhost_net.h
> +++ b/include/net/vhost_net.h
> @@ -48,4 +48,6 @@ uint64_t vhost_net_get_acked_features(VHostNetState *net);
>   
>   int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu);
>   
> +void vhost_net_virtqueue_reset(VirtIODevice *vdev, NetClientState *nc,
> +                               int vq_index);
>   #endif