net/mlx4_core: Add explicit error message when rule doesn't meet configuration

When a given flow steering rule is invalid in respect to the current
steering configuration, print the correct error message to the system log.
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/mcg.c

@@ -999,12 +999,27 @@ int mlx4_flow_attach(struct mlx4_dev *dev,
 	}
 
 	ret = mlx4_QP_FLOW_STEERING_ATTACH(dev, mailbox, size >> 2, reg_id);
-	if (ret == -ENOMEM)
+	if (ret == -ENOMEM) {
 		mlx4_err_rule(dev,
 			      "mcg table is full. Fail to register network rule\n",
 			      rule);
-	else if (ret)
-		mlx4_err_rule(dev, "Fail to register network rule\n", rule);
+	} else if (ret) {
+		if (ret == -ENXIO) {
+			if (dev->caps.steering_mode != MLX4_STEERING_MODE_DEVICE_MANAGED)
+				mlx4_err_rule(dev,
+					      "DMFS is not enabled, "
+					      "failed to register network rule.\n",
+					      rule);
+			else
+				mlx4_err_rule(dev,
+					      "Rule exceeds the dmfs_high_rate_mode limitations, "
+					      "failed to register network rule.\n",
+					      rule);
+
+		} else {
+			mlx4_err_rule(dev, "Fail to register network rule.\n", rule);
+		}
+	}
 
 	mlx4_free_cmd_mailbox(dev, mailbox);