Re: [RFC PATCH v2 6/8] vdpa: handle VIRTIO_NET_CTRL_ANNOUNCE in vhost_vdpa_net_handle_ctrl_avail

[Jason Wang]

On Wed, Oct 19, 2022 at 8:52 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Since this capability is emulated by qemu shadowed CVQ cannot forward it
> to the device.

I wonder what happens for a device that has GUEST_ANNOUNCE support on its own?

> 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 3374c21b4d..5fda405a66 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -488,9 +488,18 @@ 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) {

Interesting, I thought we can do better by forbidding the code that
goes into vhost-vDPA specific code, everything should be set at
virtio-net.c level.

Thanks

> +        /*
> +         * Guest announce capability is emulated by qemu, so dont forward to
> +         * the device.
> +         */
> +        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
>