[dpdk-dev] [PATCH] net/mlx5: fix Tx queues creation type check for scheduling

[Viacheslav Ovsiienko <viacheslavo@nvidia.com>]

The send scheduling on timestamp offload requires the Send
Queue (SQ) shares its User Access Region (UAR) with the
pacing Clock Queue. The SQ can be created by mlx5 PMD either
with DevX or with Verbs. If the SQ is being created with
DevX the dedicated UAR can be specified and all the SQs
share the single UAR. Once SQ is being created with Verbs
the SQ's UAR is allocated by the rdma-core library internally
on its own and there are no UAR sharing. This caused hardware
errors on WAIT WQEs and overall send scheduling malfunction.

If SQs are going to be created with Verbs and the send
scheduling offload is explicitly requested via tx_pp devarg
the device probing is rejected as device configuration
can't satisfy the requirements.

Fixes: 3ec73abeed52 ("net/mlx5/linux: fix Tx queue operations decision")
Fixes: 8f848f32fc24 ("net/mlx5: introduce send scheduling devargs")
Cc: stable@dpdk.org

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/net/mlx5/linux/mlx5_os.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/net/mlx5/linux/mlx5_os.c b/drivers/net/mlx5/linux/mlx5_os.c
index aa5210fa45..e3c949ffc8 100644
--- a/drivers/net/mlx5/linux/mlx5_os.c
+++ b/drivers/net/mlx5/linux/mlx5_os.c
@@ -1769,6 +1769,24 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
 	} else {
 		priv->obj_ops = ibv_obj_ops;
 	}
+	if (config->tx_pp &&
+	    (priv->config.dv_esw_en ||
+	     priv->obj_ops.txq_obj_new != mlx5_os_txq_obj_new)) {
+		/*
+		 * HAVE_MLX5DV_DEVX_UAR_OFFSET is required to support
+		 * packet pacing and already checked above. Hence, we should
+		 * only make sure the SQs will be created with DevX, not with
+		 * Verbs. Verbs allocates the SQ UAR on its own and it can't
+		 * be shared with Clock Queue UAR as it required for the
+		 * Tx scheduling feature.
+		 */
+		DRV_LOG(ERR, "Verbs SQs, UAR can't be shared"
+			     " as required for packet pacing");
+			err = ENODEV;
+			goto error;
+		err = ENODEV;
+		goto error;
+	}
 	priv->drop_queue.hrxq = mlx5_drop_action_create(eth_dev);
 	if (!priv->drop_queue.hrxq)
 		goto error;
-- 
2.18.1