Re: [PATCH v7 11/12] vdpa: Add virtio-net mac address via CVQ at start

[Jason Wang]

On Fri, Aug 5, 2022 at 2:29 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> This is needed so the destination vdpa device see the same state a the
> guest set in the source.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
> v6:
> * Map and unmap command buffers at the start and end of device usage.
>
> v5:
> * Rename s/start/load/
> * Use independent NetClientInfo to only add load callback on cvq.
> ---
>  net/vhost-vdpa.c | 43 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 10843e6d97..4f1524c2e9 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -363,11 +363,54 @@ static ssize_t vhost_vdpa_net_cvq_add(VhostVDPAState 
> *s, size_t out_len,
>      return vhost_svq_poll(svq);
>  }
>
> +static int vhost_vdpa_net_load(NetClientState *nc)
> +{
> +    VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> +    struct vhost_vdpa *v = &s->vhost_vdpa;
> +    VirtIONet *n;
> +    uint64_t features;
> +
> +    assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
> +
> +    if (!v->shadow_vqs_enabled) {
> +        return 0;
> +    }
> +
> +    n = VIRTIO_NET(v->dev->vdev);
> +    features = v->dev->vdev->host_features;
> +    if (features & BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR)) {
> +        const struct virtio_net_ctrl_hdr ctrl = {
> +            .class = VIRTIO_NET_CTRL_MAC,
> +            .cmd = VIRTIO_NET_CTRL_MAC_ADDR_SET,
> +        };

Can we build this directly from the cmd_out_buffer?

> +        char *cursor = s->cvq_cmd_out_buffer;
> +        ssize_t dev_written;
> +        virtio_net_ctrl_ack state;

I think we can read the status directly from the cmd_in_buffer.

Thanks

> +
> +        memcpy(cursor, &ctrl, sizeof(ctrl));
> +        cursor += sizeof(ctrl);
> +        memcpy(cursor, n->mac, sizeof(n->mac));
> +        cursor += sizeof(n->mac);
> +
> +        dev_written = vhost_vdpa_net_cvq_add(s, sizeof(ctrl) + 
> sizeof(n->mac),
> +                                             sizeof(state));
> +        if (unlikely(dev_written < 0)) {
> +            return dev_written;
> +        }
> +
> +        memcpy(&state, s->cvq_cmd_in_buffer, sizeof(state));
> +        return state == VIRTIO_NET_OK ? 0 : -1;
> +    }
> +
> +    return 0;
> +}
> +
>  static NetClientInfo net_vhost_vdpa_cvq_info = {
>      .type = NET_CLIENT_DRIVER_VHOST_VDPA,
>      .size = sizeof(VhostVDPAState),
>      .receive = vhost_vdpa_receive,
>      .prepare = vhost_vdpa_net_cvq_prepare,
> +    .load = vhost_vdpa_net_load,
>      .stop = vhost_vdpa_net_cvq_stop,
>      .cleanup = vhost_vdpa_cleanup,
>      .has_vnet_hdr = vhost_vdpa_has_vnet_hdr,
> --
> 2.31.1
>