virtio_net: enable big packets for large MTU values

If one enables e.g. jumbo frames without mergeable
buffers, packets won't fit in 1500 byte buffers
we use. Switch to big packet mode instead.
TODO: make sizing more exact, possibly extend small
packet mode to use larger pages.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index ea9890d619670e1abfba75fe608c2925d824cb1c..006f1a6031029392476eb9995c5e9dc69e24ccea 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2367,6 +2367,10 @@ static int virtnet_probe(struct virtio_device *vdev)
                        dev->mtu = mtu;
                        dev->max_mtu = mtu;
                }
+
+               /* TODO: size buffers correctly in this case. */
+               if (dev->mtu > ETH_DATA_LEN)
+                       vi->big_packets = true;
        }
 
        if (vi->any_header_sg)