Re: [PATCH v2 3/4] vdpa: handle VIRTIO_NET_CTRL_ANNOUNCE in vhost_vdpa_net_handle_ctrl_avail

[Michael S. Tsirkin]

On Thu, Nov 24, 2022 at 06:33:13PM +0100, Eugenio Pérez wrote:
> Since this capability is emulated by qemu shadowed CVQ cannot forward it
> to the device. Process all that command within qemu.
> 
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  net/vhost-vdpa.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 2b4b85d8f8..8172aa8449 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -489,9 +489,18 @@ static int 
> vhost_vdpa_net_handle_ctrl_avail(VhostShadowVirtqueue *svq,
>      out.iov_len = iov_to_buf(elem->out_sg, elem->out_num, 0,
>                               s->cvq_cmd_out_buffer,
>                               vhost_vdpa_net_cvq_cmd_len());
> -    dev_written = vhost_vdpa_net_cvq_add(s, out.iov_len, sizeof(status));
> -    if (unlikely(dev_written < 0)) {
> -        goto out;
> +    if (*(uint8_t *)s->cvq_cmd_out_buffer == VIRTIO_NET_CTRL_ANNOUNCE) {
> +        /*
> +         * Guest announce capability is emulated by qemu, so dont forward to
> +         * the device.
> +         */

Hmm I'm not sure why. We don't forward the status bit to guest?

> +        dev_written = sizeof(status);
> +        *s->status = VIRTIO_NET_OK;
> +    } else {
> +        dev_written = vhost_vdpa_net_cvq_add(s, out.iov_len, sizeof(status));
> +        if (unlikely(dev_written < 0)) {
> +            goto out;
> +        }
>      }
>  
>      if (unlikely(dev_written < sizeof(status))) {
> -- 
> 2.31.1