virtio: finer-grained features for virtio_net

So, we previously had a 'VIRTIO_NET_F_GSO' bit which meant that 'the
host can handle csum offload, and any TSO (v4&v6 incl ECN) or UFO
packets you might want to send.  I thought this was good enough for
Linux, but it actually isn't, since we don't do UFO in software.

So, add separate feature bits for what the host can handle.  Add
equivalent ones for the guest to say what it can handle, because LRO
is coming too (thanks Herbert!).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e44116452b7b..ad43421ab6f1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -385,6 +385,15 @@ static int virtnet_probe(struct virtio_device *vdev)
                         dev->features |= NETIF_F_TSO | NETIF_F_UFO
                                 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
                 }
+                /* Individual feature bits: what can host handle? */
+                if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_TSO4))
+                        dev->features |= NETIF_F_TSO;
+                if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_TSO6))
+                        dev->features |= NETIF_F_TSO6;
+                if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_ECN))
+                        dev->features |= NETIF_F_TSO_ECN;
+                if (gso && vdev->config->feature(vdev, VIRTIO_NET_F_HOST_UFO))
+                        dev->features |= NETIF_F_UFO;
         }
 
         /* Configuration may specify what MAC to use.  Otherwise random. */