net/mlx5e: Warn when rejecting offload attempts of IP tunnels

We silently reject offloading of IPv6 tunnels, non vxlan tunnels,
vxlan tunnels where the dst port to match is not provided, etc.

Be a bit more verbose and print a warning so the user better
realizes what went wrong here and can fix it.

Fixes: a54e20b ('net/mlx5e: Add basic TC tunnel set action for SRIOV offloads')
Fixes: bbd00f7 ('net/mlx5e: Add TC tunnel release action for SRIOV offloads')
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_tc.c

@@ -237,13 +237,16 @@ static int parse_tunnel_attr(struct mlx5e_priv *priv,
 
 		/* Full udp dst port must be given */
 		if (memchr_inv(&mask->dst, 0xff, sizeof(mask->dst)))
-			return -EOPNOTSUPP;
+			goto vxlan_match_offload_err;
 
 		if (mlx5e_vxlan_lookup_port(priv, be16_to_cpu(key->dst)) &&
 		    MLX5_CAP_ESW(priv->mdev, vxlan_encap_decap))
 			parse_vxlan_attr(spec, f);
-		else
+		else {
+			netdev_warn(priv->netdev,
+				    "%d isn't an offloaded vxlan udp dport\n", be16_to_cpu(key->dst));
 			return -EOPNOTSUPP;
+		}
 
 		MLX5_SET(fte_match_set_lyr_2_4, headers_c,
 			 udp_dport, ntohs(mask->dst));
@@ -255,7 +258,10 @@ static int parse_tunnel_attr(struct mlx5e_priv *priv,
 		MLX5_SET(fte_match_set_lyr_2_4, headers_v,
 			 udp_sport, ntohs(key->src));
 	} else { /* udp dst port must be given */
-			return -EOPNOTSUPP;
+vxlan_match_offload_err:
+		netdev_warn(priv->netdev,
+			    "IP tunnel decap offload supported only for vxlan, must set UDP dport\n");
+		return -EOPNOTSUPP;
 	}
 
 	if (dissector_uses_key(f->dissector, FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS)) {
@@ -346,6 +352,9 @@ static int __parse_cls_flower(struct mlx5e_priv *priv,
 			if (parse_tunnel_attr(priv, spec, f))
 				return -EOPNOTSUPP;
 			break;
+		case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
+			netdev_warn(priv->netdev,
+				    "IPv6 tunnel decap offload isn't supported\n");
 		default:
 			return -EOPNOTSUPP;
 		}
@@ -792,27 +801,36 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
 	int tunnel_type;
 	int err;
 
-	/* udp dst port must be given */
+	/* udp dst port must be set */
 	if (!memchr_inv(&key->tp_dst, 0, sizeof(key->tp_dst)))
-		return -EOPNOTSUPP;
+		goto vxlan_encap_offload_err;
 
 	/* setting udp src port isn't supported */
-	if (memchr_inv(&key->tp_src, 0, sizeof(key->tp_src)))
+	if (memchr_inv(&key->tp_src, 0, sizeof(key->tp_src))) {
+vxlan_encap_offload_err:
+		netdev_warn(priv->netdev,
+			    "must set udp dst port and not set udp src port\n");
 		return -EOPNOTSUPP;
+	}
 
 	if (mlx5e_vxlan_lookup_port(priv, be16_to_cpu(key->tp_dst)) &&
 	    MLX5_CAP_ESW(priv->mdev, vxlan_encap_decap)) {
 		info.tp_dst = key->tp_dst;
 		info.tun_id = tunnel_id_to_key32(key->tun_id);
 		tunnel_type = MLX5_HEADER_TYPE_VXLAN;
 	} else {
+		netdev_warn(priv->netdev,
+			    "%d isn't an offloaded vxlan udp dport\n", be16_to_cpu(key->tp_dst));
 		return -EOPNOTSUPP;
 	}
 
 	switch (family) {
 	case AF_INET:
 		info.daddr = key->u.ipv4.dst;
 		break;
+	case AF_INET6:
+		netdev_warn(priv->netdev,
+			    "IPv6 tunnel encap offload isn't supported\n");
 	default:
 		return -EOPNOTSUPP;
 	}