ice: Support UDP segmentation offload

Based on the work done by Alex Duyck on other Intel drivers, add code to
support UDP segmentation offload (USO) for the ice driver.
Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_main.c

@@ -2330,7 +2330,8 @@ static void ice_set_netdev_features(struct net_device *netdev)
 			 NETIF_F_HW_VLAN_CTAG_TX     |
 			 NETIF_F_HW_VLAN_CTAG_RX;
 
-	tso_features = NETIF_F_TSO;
+	tso_features = NETIF_F_TSO		|
+		       NETIF_F_GSO_UDP_L4;
 
 	/* set features that user can change */
 	netdev->hw_features = dflt_features | csumo_features |

drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -1925,6 +1925,7 @@ int ice_tso(struct ice_tx_buf *first, struct ice_tx_offload_params *off)
 	} ip;
 	union {
 		struct tcphdr *tcp;
+		struct udphdr *udp;
 		unsigned char *hdr;
 	} l4;
 	u64 cd_mss, cd_tso_len;
@@ -1958,10 +1959,18 @@ int ice_tso(struct ice_tx_buf *first, struct ice_tx_offload_params *off)
 
 	/* remove payload length from checksum */
 	paylen = skb->len - l4_start;
-	csum_replace_by_diff(&l4.tcp->check, (__force __wsum)htonl(paylen));
 
-	/* compute length of segmentation header */
-	off->header_len = (l4.tcp->doff * 4) + l4_start;
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) {
+		csum_replace_by_diff(&l4.udp->check,
+				     (__force __wsum)htonl(paylen));
+		/* compute length of UDP segmentation header */
+		off->header_len = sizeof(l4.udp) + l4_start;
+	} else {
+		csum_replace_by_diff(&l4.tcp->check,
+				     (__force __wsum)htonl(paylen));
+		/* compute length of TCP segmentation header */
+		off->header_len = (l4.tcp->doff * 4) + l4_start;
+	}
 
 	/* update gso_segs and bytecount */
 	first->gso_segs = skb_shinfo(skb)->gso_segs;