nfp: flower: fix mpls ether type detection

Previously it was not possible to distinguish between mpls ether types and
other ether types. This leads to incorrect classification of offloaded
filters that match on mpls ether type. For example the following two
filters overlap:

 # tc filter add dev eth0 parent ffff: \
    protocol 0x8847 flower \
    action mirred egress redirect dev eth1

 # tc filter add dev eth0 parent ffff: \
    protocol 0x0800 flower \
    action mirred egress redirect dev eth2

The driver now correctly includes the mac_mpls layer where HW stores mpls
fields, when it detects an mpls ether type. It also sets the MPLS_Q bit to
indicate that the filter should match mpls packets.

Fixes: bb055c1 ("nfp: add mpls match offloading support")
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/flower/match.c

@@ -123,6 +123,20 @@ nfp_flower_compile_mac(struct nfp_flower_mac_mpls *frame,
 			 NFP_FLOWER_MASK_MPLS_Q;
 
 		frame->mpls_lse = cpu_to_be32(t_mpls);
+	} else if (dissector_uses_key(flow->dissector,
+				      FLOW_DISSECTOR_KEY_BASIC)) {
+		/* Check for mpls ether type and set NFP_FLOWER_MASK_MPLS_Q
+		 * bit, which indicates an mpls ether type but without any
+		 * mpls fields.
+		 */
+		struct flow_dissector_key_basic *key_basic;
+
+		key_basic = skb_flow_dissector_target(flow->dissector,
+						      FLOW_DISSECTOR_KEY_BASIC,
+						      flow->key);
+		if (key_basic->n_proto == cpu_to_be16(ETH_P_MPLS_UC) ||
+		    key_basic->n_proto == cpu_to_be16(ETH_P_MPLS_MC))
+			frame->mpls_lse = cpu_to_be32(NFP_FLOWER_MASK_MPLS_Q);
 	}
 }
 

drivers/net/ethernet/netronome/nfp/flower/offload.c

@@ -264,6 +264,14 @@ nfp_flower_calculate_key_layers(struct nfp_app *app,
 		case cpu_to_be16(ETH_P_ARP):
 			return -EOPNOTSUPP;
 
+		case cpu_to_be16(ETH_P_MPLS_UC):
+		case cpu_to_be16(ETH_P_MPLS_MC):
+			if (!(key_layer & NFP_FLOWER_LAYER_MAC)) {
+				key_layer |= NFP_FLOWER_LAYER_MAC;
+				key_size += sizeof(struct nfp_flower_mac_mpls);
+			}
+			break;
+
 		/* Will be included in layer 2. */
 		case cpu_to_be16(ETH_P_8021Q):
 			break;