Re: [RFC] virtio: enforce link up

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

On Sat, Oct 14, 2023 at 06:22:34PM +0200, Vincent Jardin wrote:
> Using interface's settings, let's enforce an always on link up.
> 
> Signed-off-by: Vincent Jardin <vincent.jardin@ekinops.com>

What is going on here? Just don't set it down.

> ---
>  hw/net/virtio-net.c            | 8 ++++++++
>  include/hw/virtio/virtio-net.h | 2 ++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 29e33ea5ed..e731b4fdea 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -78,6 +78,9 @@
>     tso/gso/gro 'off'. */
>  #define VIRTIO_NET_RSC_DEFAULT_INTERVAL 300000
>  
> +/* force always link up */
> +#define VIRTIO_NET_LINK_UP false
> +
>  #define VIRTIO_NET_RSS_SUPPORTED_HASHES (VIRTIO_NET_RSS_HASH_TYPE_IPv4 | \
>                                           VIRTIO_NET_RSS_HASH_TYPE_TCPv4 | \
>                                           VIRTIO_NET_RSS_HASH_TYPE_UDPv4 | \
> @@ -447,6 +450,9 @@ static void virtio_net_set_link_status(NetClientState *nc)
>      else
>          n->status |= VIRTIO_NET_S_LINK_UP;
>  
> +    if (n->net_conf.link_up)
> +        n->status |= VIRTIO_NET_S_LINK_UP;
> +
>      if (n->status != old_status)
>          virtio_notify_config(vdev);
>  
> @@ -3947,6 +3953,8 @@ static Property virtio_net_properties[] = {
>                        VIRTIO_NET_F_GUEST_USO6, true),
>      DEFINE_PROP_BIT64("host_uso", VirtIONet, host_features,
>                        VIRTIO_NET_F_HOST_USO, true),
> +    DEFINE_PROP_BOOL("link_up", VirtIONet, net_conf.link_up,
> +                       VIRTIO_NET_LINK_UP),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
> index 55977f01f0..385bebab34 100644
> --- a/include/hw/virtio/virtio-net.h
> +++ b/include/hw/virtio/virtio-net.h
> @@ -56,6 +56,7 @@ typedef struct virtio_net_conf
>      char *duplex_str;
>      uint8_t duplex;
>      char *primary_id_str;
> +    bool link_up; /* if set enforce link up, never down */
>  } virtio_net_conf;
>  
>  /* Coalesced packets type & status */
> @@ -180,6 +181,7 @@ struct VirtIONet {
>      size_t guest_hdr_len;
>      uint64_t host_features;
>      uint32_t rsc_timeout;
> +    uint32_t link_up; /* if set enforce link up, never down */
>      uint8_t rsc4_enabled;
>      uint8_t rsc6_enabled;
>      uint8_t has_ufo;
> -- 
> 2.34.1