net/mlx5e: Validate striding RQ before enabling XDP

Currently, the driver can silently fall back to legacy RQ after enabling
XDP, even if striding RQ was active before. It happens when PAGE_SIZE is
bigger than the maximum supported stride size. This commit changes this
behavior to more straightforward: if an operation (enabling XDP) doesn't
support the current parameters (striding RQ mode), it fails.
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx5/core/en/params.c

@@ -320,22 +320,27 @@ bool slow_pci_heuristic(struct mlx5_core_dev *mdev)
 		link_speed > MLX5E_SLOW_PCI_RATIO * pci_bw;
 }
 
-bool mlx5e_striding_rq_possible(struct mlx5_core_dev *mdev,
-				struct mlx5e_params *params)
+int mlx5e_mpwrq_validate_regular(struct mlx5_core_dev *mdev, struct mlx5e_params *params)
 {
 	if (!mlx5e_check_fragmented_striding_rq_cap(mdev))
-		return false;
+		return -EOPNOTSUPP;
 
-	if (params->xdp_prog) {
-		/* XSK params are not considered here. If striding RQ is in use,
-		 * and an XSK is being opened, mlx5e_rx_mpwqe_is_linear_skb will
-		 * be called with the known XSK params.
-		 */
-		if (!mlx5e_rx_mpwqe_is_linear_skb(mdev, params, NULL))
-			return false;
-	}
+	if (params->xdp_prog && !mlx5e_rx_mpwqe_is_linear_skb(mdev, params, NULL))
+		return -EINVAL;
+
+	return 0;
+}
 
-	return true;
+int mlx5e_mpwrq_validate_xsk(struct mlx5_core_dev *mdev, struct mlx5e_params *params,
+			     struct mlx5e_xsk_param *xsk)
+{
+	if (!mlx5e_check_fragmented_striding_rq_cap(mdev))
+		return -EOPNOTSUPP;
+
+	if (!mlx5e_rx_mpwqe_is_linear_skb(mdev, params, xsk))
+		return -EINVAL;
+
+	return 0;
 }
 
 void mlx5e_init_rq_type_params(struct mlx5_core_dev *mdev,
@@ -356,8 +361,7 @@ void mlx5e_init_rq_type_params(struct mlx5_core_dev *mdev,
 
 void mlx5e_set_rq_type(struct mlx5_core_dev *mdev, struct mlx5e_params *params)
 {
-	params->rq_wq_type = mlx5e_striding_rq_possible(mdev, params) &&
-		MLX5E_GET_PFLAG(params, MLX5E_PFLAG_RX_STRIDING_RQ) ?
+	params->rq_wq_type = MLX5E_GET_PFLAG(params, MLX5E_PFLAG_RX_STRIDING_RQ) ?
 		MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ :
 		MLX5_WQ_TYPE_CYCLIC;
 }
@@ -374,7 +378,7 @@ void mlx5e_build_rq_params(struct mlx5_core_dev *mdev,
 	 */
 	if ((!MLX5E_GET_PFLAG(params, MLX5E_PFLAG_RX_CQE_COMPRESS) ||
 	     MLX5_CAP_GEN(mdev, mini_cqe_resp_stride_index)) &&
-	    mlx5e_striding_rq_possible(mdev, params) &&
+	    !mlx5e_mpwrq_validate_regular(mdev, params) &&
 	    (mlx5e_rx_mpwqe_is_linear_skb(mdev, params, NULL) ||
 	     !mlx5e_rx_is_linear_skb(params, NULL)))
 		MLX5E_SET_PFLAG(params, MLX5E_PFLAG_RX_STRIDING_RQ, true);

drivers/net/ethernet/mellanox/mlx5/core/en/params.h

@@ -92,7 +92,9 @@ void mlx5e_set_tx_cq_mode_params(struct mlx5e_params *params, u8 cq_period_mode)
 void mlx5e_set_rx_cq_mode_params(struct mlx5e_params *params, u8 cq_period_mode);
 
 bool slow_pci_heuristic(struct mlx5_core_dev *mdev);
-bool mlx5e_striding_rq_possible(struct mlx5_core_dev *mdev, struct mlx5e_params *params);
+int mlx5e_mpwrq_validate_regular(struct mlx5_core_dev *mdev, struct mlx5e_params *params);
+int mlx5e_mpwrq_validate_xsk(struct mlx5_core_dev *mdev, struct mlx5e_params *params,
+			     struct mlx5e_xsk_param *xsk);
 void mlx5e_build_rq_params(struct mlx5_core_dev *mdev, struct mlx5e_params *params);
 void mlx5e_set_rq_type(struct mlx5_core_dev *mdev, struct mlx5e_params *params);
 void mlx5e_init_rq_type_params(struct mlx5_core_dev *mdev, struct mlx5e_params *params);

drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c

@@ -30,7 +30,7 @@ bool mlx5e_validate_xsk_param(struct mlx5e_params *params,
 	 */
 	switch (params->rq_wq_type) {
 	case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
-		return mlx5e_rx_mpwqe_is_linear_skb(mdev, params, xsk);
+		return !mlx5e_mpwrq_validate_xsk(mdev, params, xsk);
 	default: /* MLX5_WQ_TYPE_CYCLIC */
 		return mlx5e_rx_is_linear_skb(params, xsk);
 	}

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

@@ -1997,10 +1997,14 @@ static int set_pflag_rx_striding_rq(struct net_device *netdev, bool enable)
 	struct mlx5e_params new_params;
 
 	if (enable) {
-		if (!mlx5e_check_fragmented_striding_rq_cap(mdev))
-			return -EOPNOTSUPP;
-		if (!mlx5e_striding_rq_possible(mdev, &priv->channels.params))
-			return -EINVAL;
+		/* Checking the regular RQ here; mlx5e_validate_xsk_param called
+		 * from mlx5e_open_xsk will check for each XSK queue, and
+		 * mlx5e_safe_switch_params will be reverted if any check fails.
+		 */
+		int err = mlx5e_mpwrq_validate_regular(mdev, &priv->channels.params);
+
+		if (err)
+			return err;
 	} else if (priv->channels.params.packet_merge.type != MLX5E_PACKET_MERGE_NONE) {
 		netdev_warn(netdev, "Can't set legacy RQ with HW-GRO/LRO, disable them first\n");
 		return -EINVAL;

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

@@ -4582,8 +4582,20 @@ static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog)
 
 	new_params = priv->channels.params;
 	new_params.xdp_prog = prog;
-	if (reset)
-		mlx5e_set_rq_type(priv->mdev, &new_params);
+
+	/* XDP affects striding RQ parameters. Block XDP if striding RQ won't be
+	 * supported with the new parameters: if PAGE_SIZE is bigger than
+	 * MLX5_MPWQE_LOG_STRIDE_SZ_MAX, striding RQ can't be used, even though
+	 * the MTU is small enough for the linear mode, because XDP uses strides
+	 * of PAGE_SIZE on regular RQs.
+	 */
+	if (reset && MLX5E_GET_PFLAG(&new_params, MLX5E_PFLAG_RX_STRIDING_RQ)) {
+		/* Checking for regular RQs here; XSK RQs were checked on XSK bind. */
+		err = mlx5e_mpwrq_validate_regular(priv->mdev, &new_params);
+		if (err)
+			goto unlock;
+	}
+
 	old_prog = priv->channels.params.xdp_prog;
 
 	err = mlx5e_safe_switch_params(priv, &new_params, NULL, NULL, reset);