net/mlx5e: Permit XDP with non-linear legacy RQ

Now that legacy RQ implements XDP in the non-linear mode, stop blocking
this configuration. Allow non-linear mode only for programs aware of
multi buffer.

XDP performance with linear mode RQ hasn't changed.

Baseline (MTU 1500, TX MPWQE, legacy RQ, single core):
 60-byte packets, XDP_DROP: 11.25 Mpps
 60-byte packets, XDP_TX: 9.0 Mpps
 60-byte packets, XDP_PASS: 668 kpps

Multi buffer (MTU 9000, TX MPWQE, legacy RQ, single core):
 60-byte packets, XDP_DROP: 10.1 Mpps
 60-byte packets, XDP_TX: 6.6 Mpps
 60-byte packets, XDP_PASS: 658 kpps
 8900-byte packets, XDP_DROP: 769 kpps (100% of sent packets)
 8900-byte packets, XDP_TX: 674 kpps (100% of sent packets)
 8900-byte packets, XDP_PASS: 637 kpps
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -3953,6 +3953,31 @@ static bool mlx5e_xsk_validate_mtu(struct net_device *netdev,
 	return true;
 }
 
+static bool mlx5e_params_validate_xdp(struct net_device *netdev, struct mlx5e_params *params)
+{
+	bool is_linear;
+
+	/* No XSK params: AF_XDP can't be enabled yet at the point of setting
+	 * the XDP program.
+	 */
+	is_linear = mlx5e_rx_is_linear_skb(params, NULL);
+
+	if (!is_linear && params->rq_wq_type != MLX5_WQ_TYPE_CYCLIC) {
+		netdev_warn(netdev, "XDP is not allowed with striding RQ and MTU(%d) > %d\n",
+			    params->sw_mtu,
+			    mlx5e_xdp_max_mtu(params, NULL));
+		return false;
+	}
+	if (!is_linear && !params->xdp_prog->aux->xdp_has_frags) {
+		netdev_warn(netdev, "MTU(%d) > %d, too big for an XDP program not aware of multi buffer\n",
+			    params->sw_mtu,
+			    mlx5e_xdp_max_mtu(params, NULL));
+		return false;
+	}
+
+	return true;
+}
+
 int mlx5e_change_mtu(struct net_device *netdev, int new_mtu,
 		     mlx5e_fp_preactivate preactivate)
 {
@@ -3972,10 +3997,7 @@ int mlx5e_change_mtu(struct net_device *netdev, int new_mtu,
 	if (err)
 		goto out;
 
-	if (params->xdp_prog &&
-	    !mlx5e_rx_is_linear_skb(&new_params, NULL)) {
-		netdev_err(netdev, "MTU(%d) > %d is not allowed while XDP enabled\n",
-			   new_mtu, mlx5e_xdp_max_mtu(params, NULL));
+	if (new_params.xdp_prog && !mlx5e_params_validate_xdp(netdev, &new_params)) {
 		err = -EINVAL;
 		goto out;
 	}
@@ -4458,15 +4480,8 @@ static int mlx5e_xdp_allowed(struct mlx5e_priv *priv, struct bpf_prog *prog)
 	new_params = priv->channels.params;
 	new_params.xdp_prog = prog;
 
-	/* No XSK params: AF_XDP can't be enabled yet at the point of setting
-	 * the XDP program.
-	 */
-	if (!mlx5e_rx_is_linear_skb(&new_params, NULL)) {
-		netdev_warn(netdev, "XDP is not allowed with MTU(%d) > %d\n",
-			    new_params.sw_mtu,
-			    mlx5e_xdp_max_mtu(&new_params, NULL));
+	if (!mlx5e_params_validate_xdp(netdev, &new_params))
 		return -EINVAL;
-	}
 
 	return 0;
 }