[PATCH] common/mlx5: fix MR lookup for non-contiguous mempool

[PATCH] common/mlx5: fix MR lookup for non-contiguous mempool

[Dmitry Kozlyuk]

Memory region (MR) lookup by address inside mempool MRs
was not accounting for the upper bound of an MR.
For mempools covered by multiple MRs this could return
a wrong MR LKey, typically resulting in an unrecoverable
TxQ failure:

    mlx5_net: Cannot change Tx QP state to INIT Invalid argument

Corresponding message from /var/log/dpdk_mlx5_port_X_txq_Y_index_Z*:

    Unexpected CQE error syndrome 0x04 CQN = 128 SQN = 4848
        wqe_counter = 0 wq_ci = 9 cq_ci = 122

This is likely to happen with --legacy-mem and IOVA-as-PA,
because EAL intentionally maps pages at non-adjacent PA
to non-adjacent VA in this mode, and MLX5 PMD works with VA.

Fixes: 690b2a88c2f7 ("common/mlx5: add mempool registration facilities")
Cc: stable@dpdk.org

Reported-by: Wang Yunjian <wangyunjian@huawei.com>
Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
Reviewed-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
---
 drivers/common/mlx5/mlx5_common_mr.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/common/mlx5/mlx5_common_mr.c b/drivers/common/mlx5/mlx5_common_mr.c
index 1537b5d428..5f7e4f6734 100644
--- a/drivers/common/mlx5/mlx5_common_mr.c
+++ b/drivers/common/mlx5/mlx5_common_mr.c
@@ -1834,12 +1834,13 @@ mlx5_mempool_reg_addr2mr(struct mlx5_mempool_reg *mpr, uintptr_t addr,
 
 	for (i = 0; i < mpr->mrs_n; i++) {
 		const struct mlx5_pmd_mr *mr = &mpr->mrs[i].pmd_mr;
-		uintptr_t mr_addr = (uintptr_t)mr->addr;
+		uintptr_t mr_start = (uintptr_t)mr->addr;
+		uintptr_t mr_end = mr_start + mr->len;
 
-		if (mr_addr <= addr) {
+		if (mr_start <= addr && addr < mr_end) {
 			lkey = rte_cpu_to_be_32(mr->lkey);
-			entry->start = mr_addr;
-			entry->end = mr_addr + mr->len;
+			entry->start = mr_start;
+			entry->end = mr_end;
 			entry->lkey = lkey;
 			break;
 		}
-- 
2.25.1

RE: [PATCH] common/mlx5: fix MR lookup for non-contiguous mempool

[Raslan Darawsheh]

Hi,

> -----Original Message-----
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Sent: Friday, January 14, 2022 12:52 PM
> To: dev@dpdk.org
> Cc: stable@dpdk.org; Wang Yunjian <wangyunjian@huawei.com>; Slava
> Ovsiienko <viacheslavo@nvidia.com>; Matan Azrad <matan@nvidia.com>
> Subject: [PATCH] common/mlx5: fix MR lookup for non-contiguous mempool
> 
> Memory region (MR) lookup by address inside mempool MRs was not
> accounting for the upper bound of an MR.
> For mempools covered by multiple MRs this could return a wrong MR LKey,
> typically resulting in an unrecoverable TxQ failure:
> 
>     mlx5_net: Cannot change Tx QP state to INIT Invalid argument
> 
> Corresponding message from /var/log/dpdk_mlx5_port_X_txq_Y_index_Z*:
> 
>     Unexpected CQE error syndrome 0x04 CQN = 128 SQN = 4848
>         wqe_counter = 0 wq_ci = 9 cq_ci = 122
> 
> This is likely to happen with --legacy-mem and IOVA-as-PA, because EAL
> intentionally maps pages at non-adjacent PA to non-adjacent VA in this
> mode, and MLX5 PMD works with VA.
> 
> Fixes: 690b2a88c2f7 ("common/mlx5: add mempool registration facilities")
> Cc: stable@dpdk.org
> 
> Reported-by: Wang Yunjian <wangyunjian@huawei.com>
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Reviewed-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

Patch applied to next-net-mlx,

Kindest regards,
Raslan Darawsheh