ice: Add mpls+tso support

Attempt to add mpls+tso support.

I don't have ice hardware available to test myself, but I just implemented
this feature in i40e and thought it might be useful to implement for ice
while this is fresh in my brain.

Hoping some one at intel will be able to test this on my behalf.
Signed-off-by: Joe Damato <jdamato@fastly.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -3329,7 +3329,9 @@ static void ice_set_netdev_features(struct net_device *netdev)
 			      vlano_features | tso_features;
 
 	/* add support for HW_CSUM on packets with MPLS header */
-	netdev->mpls_features =  NETIF_F_HW_CSUM;
+	netdev->mpls_features =  NETIF_F_HW_CSUM |
+				 NETIF_F_TSO     |
+				 NETIF_F_TSO6;
 
 	/* enable features */
 	netdev->features |= netdev->hw_features;

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

@@ -8,6 +8,7 @@
 #include <linux/prefetch.h>
 #include <linux/bpf_trace.h>
 #include <net/dsfield.h>
+#include <net/mpls.h>
 #include <net/xdp.h>
 #include "ice_txrx_lib.h"
 #include "ice_lib.h"
@@ -1748,18 +1749,24 @@ int ice_tx_csum(struct ice_tx_buf *first, struct ice_tx_offload_params *off)
 	if (skb->ip_summed != CHECKSUM_PARTIAL)
 		return 0;
 
+	protocol = vlan_get_protocol(skb);
+
+	if (eth_p_mpls(protocol))
+		ip.hdr = skb_inner_network_header(skb);
+	else
 		ip.hdr = skb_network_header(skb);
-	l4.hdr = skb_transport_header(skb);
+	l4.hdr = skb_checksum_start(skb);
 
 	/* compute outer L2 header size */
 	l2_len = ip.hdr - skb->data;
 	offset = (l2_len / 2) << ICE_TX_DESC_LEN_MACLEN_S;
 
-	protocol = vlan_get_protocol(skb);
-
-	if (protocol == htons(ETH_P_IP))
+	/* set the tx_flags to indicate the IP protocol type. this is
+	 * required so that checksum header computation below is accurate.
+	 */
+	if (ip.v4->version == 4)
 		first->tx_flags |= ICE_TX_FLAGS_IPV4;
-	else if (protocol == htons(ETH_P_IPV6))
+	else if (ip.v6->version == 6)
 		first->tx_flags |= ICE_TX_FLAGS_IPV6;
 
 	if (skb->encapsulation) {
@@ -1957,6 +1964,7 @@ int ice_tso(struct ice_tx_buf *first, struct ice_tx_offload_params *off)
 		unsigned char *hdr;
 	} l4;
 	u64 cd_mss, cd_tso_len;
+	__be16 protocol;
 	u32 paylen;
 	u8 l4_start;
 	int err;
@@ -1972,8 +1980,13 @@ int ice_tso(struct ice_tx_buf *first, struct ice_tx_offload_params *off)
 		return err;
 
 	/* cppcheck-suppress unreadVariable */
+	protocol = vlan_get_protocol(skb);
+
+	if (eth_p_mpls(protocol))
+		ip.hdr = skb_inner_network_header(skb);
+	else
 		ip.hdr = skb_network_header(skb);
-	l4.hdr = skb_transport_header(skb);
+	l4.hdr = skb_checksum_start(skb);
 
 	/* initialize outer IP header fields */
 	if (ip.v4->version == 4) {