[PATCH net-next V2 4/5] net/mlx5e: XDP, Use a single linear page per rq

[Tariq Toukan <tariqt@nvidia.com>]

From: Dragos Tatulea <dtatulea@nvidia.com>

Currently in striding rq there is one mlx5e_frag_page member per WQE for
the linear page. This linear page is used only in XDP multi-buffer mode.
This is wasteful because only one linear page is needed per rq: the page
gets refreshed on every packet, regardless of WQE. Furthermore, it is
not needed in other modes (non-XDP, XDP single-buffer).

This change moves the linear page into its own structure (struct
mlx5_mpw_linear_info) and allocates it only when necessary.

A special structure is created because an upcoming patch will extend
this structure to support fragmentation of the linear page.

This patch has no functional changes.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en.h  |  6 ++-
 .../net/ethernet/mellanox/mlx5/core/en_main.c | 37 ++++++++++++++++---
 .../net/ethernet/mellanox/mlx5/core/en_rx.c   | 17 +++++----
 3 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index c7ac6ebe8290..592234780f2b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -591,10 +591,13 @@ union mlx5e_alloc_units {
 struct mlx5e_mpw_info {
 	u16 consumed_strides;
 	DECLARE_BITMAP(skip_release_bitmap, MLX5_MPWRQ_MAX_PAGES_PER_WQE);
-	struct mlx5e_frag_page linear_page;
 	union mlx5e_alloc_units alloc_units;
 };
 
+struct mlx5e_mpw_linear_info {
+	struct mlx5e_frag_page frag_page;
+};
+
 #define MLX5E_MAX_RX_FRAGS 4
 
 struct mlx5e_rq;
@@ -689,6 +692,7 @@ struct mlx5e_rq {
 			u8                     umr_wqebbs;
 			u8                     mtts_per_wqe;
 			u8                     umr_mode;
+			struct mlx5e_mpw_linear_info *linear_info;
 			struct mlx5e_shampo_hd *shampo;
 		} mpwqe;
 	};
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 1238e5356012..aa8359a48b12 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -369,6 +369,29 @@ static int mlx5e_rq_alloc_mpwqe_info(struct mlx5e_rq *rq, int node)
 	return 0;
 }
 
+static int mlx5e_rq_alloc_mpwqe_linear_info(struct mlx5e_rq *rq, int node,
+					    struct mlx5e_params *params,
+					    struct mlx5e_rq_opt_param *rqo,
+					    u32 *pool_size)
+{
+	struct mlx5_core_dev *mdev = rq->mdev;
+	struct mlx5e_mpw_linear_info *li;
+
+	if (mlx5e_rx_mpwqe_is_linear_skb(mdev, params, rqo) ||
+	    !params->xdp_prog)
+		return 0;
+
+	li = kvzalloc_node(sizeof(*li), GFP_KERNEL, node);
+	if (!li)
+		return -ENOMEM;
+
+	rq->mpwqe.linear_info = li;
+
+	/* additional page per packet for the linear part */
+	*pool_size *= 2;
+
+	return 0;
+}
 
 static u8 mlx5e_mpwrq_access_mode(enum mlx5e_mpwrq_umr_mode umr_mode)
 {
@@ -915,10 +938,6 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
 			mlx5e_mpwqe_get_log_rq_size(mdev, params, rqo);
 		pool_order = rq->mpwqe.page_shift - PAGE_SHIFT;
 
-		if (!mlx5e_rx_mpwqe_is_linear_skb(mdev, params, rqo) &&
-		    params->xdp_prog)
-			pool_size *= 2; /* additional page per packet for the linear part */
-
 		rq->mpwqe.log_stride_sz =
 				mlx5e_mpwqe_get_log_stride_size(mdev, params,
 								rqo);
@@ -936,10 +955,15 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
 		if (err)
 			goto err_rq_mkey;
 
-		err = mlx5_rq_shampo_alloc(mdev, params, rq_param, rq, node);
+		err = mlx5e_rq_alloc_mpwqe_linear_info(rq, node, params, rqo,
+						       &pool_size);
 		if (err)
 			goto err_free_mpwqe_info;
 
+		err = mlx5_rq_shampo_alloc(mdev, params, rq_param, rq, node);
+		if (err)
+			goto err_free_mpwqe_linear_info;
+
 		break;
 	default: /* MLX5_WQ_TYPE_CYCLIC */
 		err = mlx5_wq_cyc_create(mdev, &rq_param->wq, rqc_wq,
@@ -1054,6 +1078,8 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
 	switch (rq->wq_type) {
 	case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
 		mlx5e_rq_free_shampo(rq);
+err_free_mpwqe_linear_info:
+		kvfree(rq->mpwqe.linear_info);
 err_free_mpwqe_info:
 		kvfree(rq->mpwqe.info);
 err_rq_mkey:
@@ -1081,6 +1107,7 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq)
 	switch (rq->wq_type) {
 	case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
 		mlx5e_rq_free_shampo(rq);
+		kvfree(rq->mpwqe.linear_info);
 		kvfree(rq->mpwqe.info);
 		mlx5_core_destroy_mkey(rq->mdev, be32_to_cpu(rq->mpwqe.umr_mkey_be));
 		mlx5e_free_mpwqe_rq_drop_page(rq);
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index f5c0e2a0ada9..feb042d84b8e 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -1869,6 +1869,7 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
 	struct mlx5e_frag_page *frag_page = &wi->alloc_units.frag_pages[page_idx];
 	u16 headlen = min_t(u16, MLX5E_RX_MAX_HEAD, cqe_bcnt);
 	struct mlx5e_frag_page *head_page = frag_page;
+	struct mlx5e_frag_page *linear_page = NULL;
 	struct mlx5e_xdp_buff *mxbuf = &rq->mxbuf;
 	u32 page_size = BIT(rq->mpwqe.page_shift);
 	u32 frag_offset    = head_offset;
@@ -1897,13 +1898,15 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
 	if (prog) {
 		/* area for bpf_xdp_[store|load]_bytes */
 		net_prefetchw(netmem_address(frag_page->netmem) + frag_offset);
+
+		linear_page = &rq->mpwqe.linear_info->frag_page;
 		if (unlikely(mlx5e_page_alloc_fragmented(rq->page_pool,
-							 &wi->linear_page))) {
+							 linear_page))) {
 			rq->stats->buff_alloc_err++;
 			return NULL;
 		}
 
-		va = netmem_address(wi->linear_page.netmem);
+		va = netmem_address(linear_page->netmem);
 		net_prefetchw(va); /* xdp_frame data area */
 		linear_hr = XDP_PACKET_HEADROOM;
 		linear_data_len = 0;
@@ -1966,10 +1969,10 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
 				for (pfp = head_page; pfp < frag_page; pfp++)
 					pfp->frags++;
 
-				wi->linear_page.frags++;
+				linear_page->frags++;
 			}
 			mlx5e_page_release_fragmented(rq->page_pool,
-						      &wi->linear_page);
+						      linear_page);
 			return NULL; /* page/packet was consumed by XDP */
 		}
 
@@ -1988,13 +1991,13 @@ mlx5e_skb_from_cqe_mpwrq_nonlinear(struct mlx5e_rq *rq, struct mlx5e_mpw_info *w
 			mxbuf->xdp.data - mxbuf->xdp.data_meta);
 		if (unlikely(!skb)) {
 			mlx5e_page_release_fragmented(rq->page_pool,
-						      &wi->linear_page);
+						      linear_page);
 			return NULL;
 		}
 
 		skb_mark_for_recycle(skb);
-		wi->linear_page.frags++;
-		mlx5e_page_release_fragmented(rq->page_pool, &wi->linear_page);
+		linear_page->frags++;
+		mlx5e_page_release_fragmented(rq->page_pool, linear_page);
 
 		if (xdp_buff_has_frags(&mxbuf->xdp)) {
 			struct mlx5e_frag_page *pagep;
-- 
2.44.0