Ping.
Please could you help to review this patch?
Thanks.
Ruifeng
> -----Original Message-----
> From: Ruifeng Wang <ruifeng.w...@arm.com>
> Sent: Tuesday, January 4, 2022 11:01 AM
> To: ma...@nvidia.com; viachesl...@nvidia.com
> Cc: dev@dpdk.org; Honnappa Nagarahalli
> <honnappa.nagaraha...@arm.com>; sta...@dpdk.org; nd <n...@arm.com>;
> Ruifeng Wang <ruifeng.w...@arm.com>
> Subject: [PATCH] net/mlx5: fix risk in Rx descriptor read in NEON vector path
>
> In NEON vector PMD, vector load loads two contiguous 8B of descriptor data
> into vector register. Given vector load ensures no 16B atomicity, read of the
> word that includes op_own field could be reordered after read of other
> words. In this case, some words could contain invalid data.
>
> Reloaded qword0 after read barrier to update vector register. This ensures
> that the fetched data is correct.
>
> Testpmd single core test on N1SDP/ThunderX2 showed no performance
> drop.
>
> Fixes: 1742c2d9fab0 ("net/mlx5: fix synchronization on polling Rx
> completions")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Ruifeng Wang <ruifeng.w...@arm.com>
> ---
> drivers/net/mlx5/mlx5_rxtx_vec_neon.h | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
> b/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
> index b1d16baa61..b1ec615b51 100644
> --- a/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
> +++ b/drivers/net/mlx5/mlx5_rxtx_vec_neon.h
> @@ -647,6 +647,14 @@ rxq_cq_process_v(struct mlx5_rxq_data *rxq,
> volatile struct mlx5_cqe *cq,
> c0 = vld1q_u64((uint64_t *)(p0 + 48));
> /* Synchronize for loading the rest of blocks. */
> rte_io_rmb();
> + /* B.0 (CQE 3) reload lower half of the block. */
> + c3 = vld1q_lane_u64((uint64_t *)(p3 + 48), c3, 0);
> + /* B.0 (CQE 2) reload lower half of the block. */
> + c2 = vld1q_lane_u64((uint64_t *)(p2 + 48), c2, 0);
> + /* B.0 (CQE 1) reload lower half of the block. */
> + c1 = vld1q_lane_u64((uint64_t *)(p1 + 48), c1, 0);
> + /* B.0 (CQE 0) reload lower half of the block. */
> + c0 = vld1q_lane_u64((uint64_t *)(p0 + 48), c0, 0);
> /* Prefetch next 4 CQEs. */
> if (pkts_n - pos >= 2 * MLX5_VPMD_DESCS_PER_LOOP) {
> unsigned int next = pos +
> MLX5_VPMD_DESCS_PER_LOOP;
> --
> 2.25.1
