[dpdk-dev] [PATCH v3 2/6] net/mlx5: fix external memory registration

[Yongseok Koh <yskoh@mellanox.com>]

Secondary process is not allowed to register MR due to a restriction of
library and kernel driver.

Fixes: 7e43a32ee060 ("net/mlx5: support externally allocated static memory")
Cc: stable@dpdk.org

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>
---
 doc/guides/nics/mlx5.rst   |  5 +++++
 drivers/net/mlx5/mlx5_mr.c | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index f4db921f7f..fa9bf73da7 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -86,6 +86,11 @@ Limitations
 
   - Forked secondary process not supported.
   - All mempools must be initialized before rte_eth_dev_start().
+  - External memory unregistered in EAL memseg list cannot be used for DMA
+    unless such memory has been registered by ``mlx5_mr_update_ext_mp()`` in
+    primary process and remapped to the same virtual address in secondary
+    process. If the external memory is registered by primary process but has
+    different virtual address in secondary process, unexpected error may happen.
 
 - Flow pattern without any specific vlan will match for vlan packets as well:
 
diff --git a/drivers/net/mlx5/mlx5_mr.c b/drivers/net/mlx5/mlx5_mr.c
index 3718877299..e7f55be6e1 100644
--- a/drivers/net/mlx5/mlx5_mr.c
+++ b/drivers/net/mlx5/mlx5_mr.c
@@ -1185,6 +1185,7 @@ mlx5_mr_update_ext_mp_cb(struct rte_mempool *mp, void *opaque,
 	struct mlx5_mr_cache entry;
 	uint32_t lkey;
 
+	assert(rte_eal_process_type() == RTE_PROC_PRIMARY);
 	/* If already registered, it should return. */
 	rte_rwlock_read_lock(&priv->mr.rwlock);
 	lkey = mr_lookup_dev(dev, &entry, addr);
@@ -1400,6 +1401,15 @@ mlx5_tx_update_ext_mp(struct mlx5_txq_data *txq, uintptr_t addr,
 	struct mlx5_mr_ctrl *mr_ctrl = &txq->mr_ctrl;
 	struct mlx5_priv *priv = txq_ctrl->priv;
 
+	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
+		DRV_LOG(WARNING,
+			"port %u using address (%p) from unregistered mempool"
+			" having externally allocated memory"
+			" in secondary process, please create mempool"
+			" prior to rte_eth_dev_start()",
+			PORT_ID(priv), (void *)addr);
+		return UINT32_MAX;
+	}
 	mlx5_mr_update_ext_mp(ETH_DEV(priv), mr_ctrl, mp);
 	return mlx5_tx_addr2mr_bh(txq, addr);
 }
-- 
2.11.0