[PATCH net V2 1/3] net/mlx5e: SHAMPO, Fix header mapping for 64K pages

Tariq Toukan
2025-11-04T06:49:11Z

From: Dragos Tatulea <dtatulea@nvidia.com>

HW-GRO is broken on mlx5 for 64K page sizes. The patch in the fixes tag
didn't take into account larger page sizes when doing an align down
of max_ksm_entries. For 64K page size, max_ksm_entries is 0 which will skip
mapping header pages via WQE UMR. This breaks header-data split
and will result in the following syndrome:

mlx5_core 0000:00:08.0 eth2: Error cqe on cqn 0x4c9, ci 0x0, qn 0x1133, opcode 0xe, syndrome 0x4, vendor syndrome 0x32
00000000: 00 00 00 00 04 4a 00 00 00 00 00 00 20 00 93 32
00000010: 55 00 00 00 fb cc 00 00 00 00 00 00 07 18 00 00
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4a
00000030: 00 00 3b c7 93 01 32 04 00 00 00 00 00 00 bf e0
mlx5_core 0000:00:08.0 eth2: ERR CQE on RQ: 0x1133

Furthermore, the function that fills in WQE UMRs for the headers
(mlx5e_build_shampo_hd_umr()) only supports mapping page sizes that
fit in a single UMR WQE.

This patch goes back to the old non-aligned max_ksm_entries value and it
changes mlx5e_build_shampo_hd_umr() to support mapping a large page over
multiple UMR WQEs.

This means that mlx5e_build_shampo_hd_umr() can now leave a page only
partially mapped. The caller, mlx5e_alloc_rx_hd_mpwqe(), ensures that
there are enough UMR WQEs to cover complete pages by working on
ksm_entries that are multiples of MLX5E_SHAMPO_WQ_HEADER_PER_PAGE.

Fixes: 8a0ee54027b1 ("net/mlx5e: SHAMPO, Simplify UMR allocation for headers")
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
.../net/ethernet/mellanox/mlx5/core/en_rx.c | 36 +++++++++----------
1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 26621a2972ec..0c031954ca30 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -671,7 +671,7 @@ static int mlx5e_build_shampo_hd_umr(struct mlx5e_rq *rq,
u16 pi, header_offset, err, wqe_bbs;
u32 lkey = rq->mdev->mlx5e_res.hw_objs.mkey;
struct mlx5e_umr_wqe *umr_wqe;
- int headroom, i = 0;
+ int headroom, i;

headroom = rq->buff.headroom;
wqe_bbs = MLX5E_KSM_UMR_WQEBBS(ksm_entries);
@@ -679,25 +679,24 @@ static int mlx5e_build_shampo_hd_umr(struct mlx5e_rq *rq,
umr_wqe = mlx5_wq_cyc_get_wqe(&sq->wq, pi);
build_ksm_umr(sq, umr_wqe, shampo->mkey_be, index, ksm_entries);

- WARN_ON_ONCE(ksm_entries & (MLX5E_SHAMPO_WQ_HEADER_PER_PAGE - 1));
- while (i < ksm_entries) {
- struct mlx5e_frag_page *frag_page = mlx5e_shampo_hd_to_frag_page(rq, index);
+ for (i = 0; i < ksm_entries; i++, index++) {
+ struct mlx5e_frag_page *frag_page;
u64 addr;

- err = mlx5e_page_alloc_fragmented(rq->hd_page_pool, frag_page);
- if (unlikely(err))
- goto err_unmap;
+ frag_page = mlx5e_shampo_hd_to_frag_page(rq, index);
+ header_offset = mlx5e_shampo_hd_offset(index);
+ if (!header_offset) {
+ err = mlx5e_page_alloc_fragmented(rq->hd_page_pool,
+ frag_page);
+ if (err)
+ goto err_unmap;
+ }

addr = page_pool_get_dma_addr_netmem(frag_page->netmem);
-
- for (int j = 0; j < MLX5E_SHAMPO_WQ_HEADER_PER_PAGE; j++) {
- header_offset = mlx5e_shampo_hd_offset(index++);
-
- umr_wqe->inline_ksms[i++] = (struct mlx5_ksm) {
- .key = cpu_to_be32(lkey),
- .va = cpu_to_be64(addr + header_offset + headroom),
- };
- }
+ umr_wqe->inline_ksms[i] = (struct mlx5_ksm) {
+ .key = cpu_to_be32(lkey),
+ .va = cpu_to_be64(addr + header_offset + headroom),
+ };
}

sq->db.wqe_info[pi] = (struct mlx5e_icosq_wqe_info) {
@@ -713,7 +712,7 @@ static int mlx5e_build_shampo_hd_umr(struct mlx5e_rq *rq,
return 0;

err_unmap:
- while (--i) {
+ while (--i >= 0) {
--index;
header_offset = mlx5e_shampo_hd_offset(index);
if (!header_offset) {
@@ -735,8 +734,7 @@ static int mlx5e_alloc_rx_hd_mpwqe(struct mlx5e_rq *rq)
struct mlx5e_icosq *sq = rq->icosq;
int i, err, max_ksm_entries, len;

- max_ksm_entries = ALIGN_DOWN(MLX5E_MAX_KSM_PER_WQE(rq->mdev),
- MLX5E_SHAMPO_WQ_HEADER_PER_PAGE);
+ max_ksm_entries = MLX5E_MAX_KSM_PER_WQE(rq->mdev);
ksm_entries = bitmap_find_window(shampo->bitmap,
shampo->hd_per_wqe,
shampo->hd_per_wq, shampo->pi);
--
2.31.1