xen-netback: Unconditionally set NETIF_F_RXCSUM

There is no mechanism to insist that a guest always generates a packet
with good checksum (at least for IPv4) so we must handle checksum
offloading from the guest and hence should set NETIF_F_RXCSUM.
Signed-off-by: NPaul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/xen-netback/interface.c

@@ -321,7 +321,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
 	dev->hw_features = NETIF_F_SG |
 		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
 		NETIF_F_TSO;
-	dev->features = dev->hw_features;
+	dev->features = dev->hw_features | NETIF_F_RXCSUM;
 	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);
 
 	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;