Re: [PATCH RFC 1/1] vdpa: Return -EINVAL if device's ack is VIRTIO_NET_ERR

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jun 14, 2023 at 09:01:47PM +0800, Hawkins Jiawei 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")
> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com>
> ---
>  net/vhost-vdpa.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 37cdc84562..630c9bf71e 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -651,8 +651,9 @@ 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;
> @@ -676,8 +677,11 @@ 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;
>  }

I think EIO would be better, we have too many EINVAL cases,
making things hard to debug.


>  
>  static int vhost_vdpa_net_load(NetClientState *nc)
> -- 
> 2.25.1