[PATCH][focal/linux] net/mlx5e: Fix page DMA map/unmap attributes

Tim Gardner tim.gardner at canonical.com
Thu Mar 31 13:25:10 UTC 2022

From: Aya Levin <ayal at nvidia.com>

BugLink: https://bugs.launchpad.net/bugs/1967292

Driver initiates DMA sync, hence it may skip CPU sync. Add
DMA_ATTR_SKIP_CPU_SYNC as input attribute both to dma_map_page and
dma_unmap_page to avoid redundant sync with the CPU.
When forcing the device to work with SWIOTLB, the extra sync might cause
data corruption. The driver unmaps the whole page while the hardware
used just a part of the bounce buffer. So syncing overrides the entire
page with bounce buffer that only partially contains real data.

Fixes: bc77b240b3c5 ("net/mlx5e: Add fragmented memory support for RX multi packet WQE")
Fixes: db05815b36cb ("net/mlx5e: Add XSK zero-copy support")
Signed-off-by: Aya Levin <ayal at nvidia.com>
Reviewed-by: Gal Pressman <gal at nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm at nvidia.com>
(backported from commit 0b7cfa4082fbf550595bc0e40f05614bd83bf0cd)
[rtg - drivers/net/ethernet/mellanox/mlx5/core/en/xsk/pool.c does not exist]
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>

commit 0b7cfa4082fbf550595bc0e40f05614bd83bf0cd has already been included in 5.13.0-40.45 and 5.15.0-19.19

 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 386f49949a23d..3ae7a3973c745 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -248,8 +248,8 @@ static inline int mlx5e_page_alloc_pool(struct mlx5e_rq *rq,
 	if (unlikely(!dma_info->page))
 		return -ENOMEM;
-	dma_info->addr = dma_map_page(rq->pdev, dma_info->page, 0,
-				      PAGE_SIZE, rq->buff.map_dir);
+	dma_info->addr = dma_map_page_attrs(rq->pdev, dma_info->page, 0, PAGE_SIZE,
+					    rq->buff.map_dir, DMA_ATTR_SKIP_CPU_SYNC);
 	if (unlikely(dma_mapping_error(rq->pdev, dma_info->addr))) {
 		page_pool_recycle_direct(rq->page_pool, dma_info->page);
 		dma_info->page = NULL;
@@ -270,7 +270,8 @@ static inline int mlx5e_page_alloc(struct mlx5e_rq *rq,
 void mlx5e_page_dma_unmap(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info)
-	dma_unmap_page(rq->pdev, dma_info->addr, PAGE_SIZE, rq->buff.map_dir);
+	dma_unmap_page_attrs(rq->pdev, dma_info->addr, PAGE_SIZE, rq->buff.map_dir,
 void mlx5e_page_release_dynamic(struct mlx5e_rq *rq,

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