Re: [PATCH v2] vdpa: Return -EINVAL if device ack is VIRTIO_NET_ERR

[Jason Wang <jasowang@redhat.com>]

On Tue, Jun 27, 2023 at 10:36 PM Hawkins Jiawei <yin31149@gmail.com> wrote:
>
> According to VirtIO standard, "The class, command and
> command-specific-data are set by the driver,
> and the device sets the ack byte.
> There is little it can do except issue a diagnostic
> if ack is not VIRTIO_NET_OK."
>
> Therefore, QEMU should stop sending the queued SVQ commands and
> cancel the device startup if the device's ack is not VIRTIO_NET_OK.
>
> Yet the problem is that, vhost_vdpa_net_load_x() returns 1 based on
> `*s->status != VIRTIO_NET_OK` when the device's ack is VIRTIO_NET_ERR.
> As a result, net->nc->info->load() also returns 1, this makes
> vhost_net_start_one() incorrectly assume the device state is
> successfully loaded by vhost_vdpa_net_load() and return 0, instead of
> goto `fail` label to cancel the device startup, as vhost_net_start_one()
> only cancels the device startup when net->nc->info->load() returns a
> negative value.
>
> This patch fixes this problem by returning -EINVAL when the device's
> ack is not VIRTIO_NET_OK.
>
> Fixes: f73c0c43ac ("vdpa: extract vhost_vdpa_net_load_mac from vhost_vdpa_net_load")
> Fixes: f64c7cda69 ("vdpa: Add vhost_vdpa_net_load_mq")
> Fixes: 0b58d3686a ("vdpa: Add vhost_vdpa_net_load_offloads()")
> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks

> ---
> v2:
>  - fix the same bug in vhost_vdpa_net_load_offloads()
>
> v1: https://lore.kernel.org/all/cover.1686746406.git.yin31149@gmail.com/
>
>  net/vhost-vdpa.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index e19ab063fa..6f6a5c6df6 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -646,8 +646,9 @@ static int vhost_vdpa_net_load_mac(VhostVDPAState *s, const VirtIONet *n)
>          if (unlikely(dev_written < 0)) {
>              return dev_written;
>          }
> -
> -        return *s->status != VIRTIO_NET_OK;
> +        if (*s->status != VIRTIO_NET_OK) {
> +            return -EINVAL;
> +        }
>      }
>
>      return 0;
> @@ -670,8 +671,11 @@ static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
>      if (unlikely(dev_written < 0)) {
>          return dev_written;
>      }
> +    if (*s->status != VIRTIO_NET_OK) {
> +        return -EINVAL;
> +    }
>
> -    return *s->status != VIRTIO_NET_OK;
> +    return 0;
>  }
>
>  static int vhost_vdpa_net_load_offloads(VhostVDPAState *s,
> @@ -708,8 +712,11 @@ static int vhost_vdpa_net_load_offloads(VhostVDPAState *s,
>      if (unlikely(dev_written < 0)) {
>          return dev_written;
>      }
> +    if (*s->status != VIRTIO_NET_OK) {
> +        return -EINVAL;
> +    }
>
> -    return *s->status != VIRTIO_NET_OK;
> +    return 0;
>  }
>
>  static int vhost_vdpa_net_load(NetClientState *nc)
> --
> 2.25.1
>