Re: [PATCH v3 5/6] vdpa: Add vhost_vdpa_net_load_offloads()

[Eugenio Perez Martin]

On Thu, Jun 1, 2023 at 3:49 PM Hawkins Jiawei <yin31149@gmail.com> wrote:
>
> This patch introduces vhost_vdpa_net_load_offloads() to
> restore offloads state at device's startup.
>
> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
> ---
>  net/vhost-vdpa.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index e907a3c792..0e647886d1 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -678,6 +678,40 @@ static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
>      return *s->status != VIRTIO_NET_OK;
>  }
>
> +static int vhost_vdpa_net_load_offloads(VhostVDPAState *s,
> +                                        const VirtIONet *n)
> +{
> +    uint64_t offloads;
> +    ssize_t dev_written;
> +
> +    if (!virtio_vdev_has_feature(&n->parent_obj,
> +                                 VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
> +        return 0;
> +    }
> +
> +    offloads = cpu_to_le64(n->curr_guest_offloads);

n->curr_guest_offloads is already stored in CPU order, we should only
byte-swap it by the time of sending.

Thanks!

> +
> +    if (offloads == virtio_net_supported_guest_offloads(n)) {
> +        /*
> +         * According to VirtIO standard, "Upon feature negotiation
> +         * corresponding offload gets enabled to preserve
> +         * backward compatibility."
> +         * So we do not need to send this CVQ command if the guest
> +         * also enables all supported offloads.
> +         */
> +        return 0;
> +    }
> +
> +    dev_written = vhost_vdpa_net_load_cmd(s, VIRTIO_NET_CTRL_GUEST_OFFLOADS,
> +                                          VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET,
> +                                          &offloads, sizeof(offloads));
> +    if (unlikely(dev_written < 0)) {
> +        return dev_written;
> +    }
> +
> +    return *s->status != VIRTIO_NET_OK;
> +}
> +
>  static int vhost_vdpa_net_load(NetClientState *nc)
>  {
>      VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
> @@ -700,6 +734,10 @@ static int vhost_vdpa_net_load(NetClientState *nc)
>      if (unlikely(r)) {
>          return r;
>      }
> +    r = vhost_vdpa_net_load_offloads(s, n);
> +    if (unlikely(r)) {
> +        return r;
> +    }
>
>      return 0;
>  }
> --
> 2.25.1
>