virtio net: Add ethtool ops for SG/GSO

This patch adds some basic ethtool operations to virtio_net so
I could test SG without GSO (which was really useful because TSO
turned out to be buggy :)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (remove MTU setting)

drivers/net/virtio_net.c

@@ -19,6 +19,7 @@
 //#define DEBUG
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
+#include <linux/ethtool.h>
 #include <linux/module.h>
 #include <linux/virtio.h>
 #include <linux/virtio_net.h>
@@ -408,6 +409,22 @@ static int virtnet_close(struct net_device *dev)
 	return 0;
 }
 
+static int virtnet_set_tx_csum(struct net_device *dev, u32 data)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	struct virtio_device *vdev = vi->vdev;
+
+	if (data && !virtio_has_feature(vdev, VIRTIO_NET_F_CSUM))
+		return -ENOSYS;
+
+	return ethtool_op_set_tx_hw_csum(dev, data);
+}
+
+static struct ethtool_ops virtnet_ethtool_ops = {
+	.set_tx_csum = virtnet_set_tx_csum,
+	.set_sg = ethtool_op_set_sg,
+};
+
 static int virtnet_probe(struct virtio_device *vdev)
 {
 	int err;
@@ -427,6 +444,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	dev->poll_controller = virtnet_netpoll;
 #endif
+	SET_ETHTOOL_OPS(dev, &virtnet_ethtool_ops);
 	SET_NETDEV_DEV(dev, &vdev->dev);
 
 	/* Do we support "hardware" checksums? */