net/mlx5e: Limit UMR length to the device's limitation

ConnectX-4 UMR (User Memory Region) MTT translation table offset in WQE
is limited to U16_MAX, before this patch we ignored that limitation and
requested the maximum possible UMR translation length that the netdev
might need (MAX channels * MAX pages per channel).
In case of a system with #cores > 32 and when linear WQE allocation fails,
falling back to using UMR WQEs will cause the RQ (Receive Queue) to get
stuck.

Here we limit UMR length to min(U16_MAX, max required pages) (while
considering the required alignments) on driver load, by default U16_MAX is
sufficient since the default RX rings value guarantees that we are in
range, dynamically (on set_ringparam/set_channels) we will check if the
new required UMR length (num mtts) is still in range, if not, fail the
request.

Fixes: bc77b240b3c5 ('net/mlx5e: Add fragmented memory support for RX multi packet WQE')
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index 4a3757e60441..9cfe4088d008 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -373,6 +373,7 @@ static int mlx5e_set_ringparam(struct net_device *dev,
 	u16 min_rx_wqes;
 	u8 log_rq_size;
 	u8 log_sq_size;
+	u32 num_mtts;
 	int err = 0;
 
 	if (param->rx_jumbo_pending) {
@@ -397,6 +398,15 @@ static int mlx5e_set_ringparam(struct net_device *dev,
 			    1 << mlx5_max_log_rq_size(rq_wq_type));
 		return -EINVAL;
 	}
+
+	num_mtts = MLX5E_REQUIRED_MTTS(priv->params.num_channels, param->rx_pending);
+	if (priv->params.rq_wq_type == MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ &&
+	    !MLX5E_VALID_NUM_MTTS(num_mtts)) {
+		netdev_info(dev, "%s: rx_pending (%d) request can't be satisfied, try to reduce.\n",
+			    __func__, param->rx_pending);
+		return -EINVAL;
+	}
+
 	if (param->tx_pending < (1 << MLX5E_PARAMS_MINIMUM_LOG_SQ_SIZE)) {
 		netdev_info(dev, "%s: tx_pending (%d) < min (%d)\n",
 			    __func__, param->tx_pending,
@@ -454,6 +464,7 @@ static int mlx5e_set_channels(struct net_device *dev,
 	unsigned int count = ch->combined_count;
 	bool arfs_enabled;
 	bool was_opened;
+	u32 num_mtts;
 	int err = 0;
 
 	if (!count) {
@@ -472,6 +483,14 @@ static int mlx5e_set_channels(struct net_device *dev,
 		return -EINVAL;
 	}
 
+	num_mtts = MLX5E_REQUIRED_MTTS(count, BIT(priv->params.log_rq_size));
+	if (priv->params.rq_wq_type == MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ &&
+	    !MLX5E_VALID_NUM_MTTS(num_mtts)) {
+		netdev_info(dev, "%s: rx count (%d) request can't be satisfied, try to reduce.\n",
+			    __func__, count);
+		return -EINVAL;
+	}
+
 	if (priv->params.num_channels == count)
 		return 0;