Subject: Re: [xdp-hints] Re: [PATCH bpf-next v7 15/17] net/mlx5e: Introduce wrapper for xdp_buff

From: Toke Høiland-Jørgensen <[email-masked]>
Date: Thu, 12 Jan 2023 22:55:05 +0100

Toke Høiland-Jørgensen <[email-masked]> writes:

> Stanislav Fomichev <[email-masked]> writes:
>
>> On Thu, Jan 12, 2023 at 12:07 AM Tariq Toukan <[email-masked]> wrote:
>>>
>>>
>>>
>>> On 12/01/2023 2:32, Stanislav Fomichev wrote:
>>> > From: Toke Høiland-Jørgensen <[email-masked]>
>>> >
>>> > Preparation for implementing HW metadata kfuncs. No functional change.
>>> >
>>> > Cc: Tariq Toukan <[email-masked]>
>>> > Cc: Saeed Mahameed <[email-masked]>
>>> > Cc: John Fastabend <[email-masked]>
>>> > Cc: David Ahern <[email-masked]>
>>> > Cc: Martin KaFai Lau <[email-masked]>
>>> > Cc: Jakub Kicinski <[email-masked]>
>>> > Cc: Willem de Bruijn <[email-masked]>
>>> > Cc: Jesper Dangaard Brouer <[email-masked]>
>>> > Cc: Anatoly Burakov <[email-masked]>
>>> > Cc: Alexander Lobakin <[email-masked]>
>>> > Cc: Magnus Karlsson <[email-masked]>
>>> > Cc: Maryam Tahhan <[email-masked]>
>>> > Cc: [email-masked]
>>> > Cc: [email-masked]
>>> > Signed-off-by: Toke Høiland-Jørgensen <[email-masked]>
>>> > Signed-off-by: Stanislav Fomichev <[email-masked]>
>>> > ---
>>> >   drivers/net/ethernet/mellanox/mlx5/core/en.h  |  1 +
>>> >   .../net/ethernet/mellanox/mlx5/core/en/xdp.c  |  3 +-
>>> >   .../net/ethernet/mellanox/mlx5/core/en/xdp.h  |  6 +-
>>> >   .../ethernet/mellanox/mlx5/core/en/xsk/rx.c   | 25 ++++----
>>> >   .../net/ethernet/mellanox/mlx5/core/en_rx.c   | 58 +++++++++----------
>>> >   5 files changed, 50 insertions(+), 43 deletions(-)
>>> >
>>> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
>>> > index 2d77fb8a8a01..af663978d1b4 100644
>>> > --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
>>> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
>>> > @@ -469,6 +469,7 @@ struct mlx5e_txqsq {
>>> >   union mlx5e_alloc_unit {
>>> >       struct page *page;
>>> >       struct xdp_buff *xsk;
>>> > +     struct mlx5e_xdp_buff *mxbuf;
>>>
>>> In XSK files below you mix usage of both alloc_units[page_idx].mxbuf and
>>> alloc_units[page_idx].xsk, while both fields share the memory of a union.
>>>
>>> As struct mlx5e_xdp_buff wraps struct xdp_buff, I think that you just
>>> need to change the existing xsk field type from struct xdp_buff *xsk
>>> into struct mlx5e_xdp_buff *xsk and align the usage.
>>
>> Hmmm, good point. I'm actually not sure how it works currently.
>> mlx5e_alloc_unit.mxbuf doesn't seem to be initialized anywhere? Toke,
>> am I missing something?
>
> It's initialised piecemeal in different places; but yeah, we're mixing
> things a bit...
>
>> I'm thinking about something like this:
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h
>> b/drivers/net/ethernet/mellanox/mlx5/core/en.h
>> index af663978d1b4..2d77fb8a8a01 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
>> @@ -469,7 +469,6 @@ struct mlx5e_txqsq {
>>  union mlx5e_alloc_unit {
>>         struct page *page;
>>         struct xdp_buff *xsk;
>> -       struct mlx5e_xdp_buff *mxbuf;
>>  };
>
> Hmm, for consistency with the non-XSK path we should rather go the other
> direction and lose the xsk member, moving everything to mxbuf? Let me
> give that a shot...

Something like the below?

-Toke

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 6de02d8aeab8..cb9cdb6421c5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -468,7 +468,6 @@ struct mlx5e_txqsq {
 
 union mlx5e_alloc_unit {
 	struct page *page;
-	struct xdp_buff *xsk;
 	struct mlx5e_xdp_buff *mxbuf;
 };
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
index cb568c62aba0..95694a25ec31 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.h
@@ -33,6 +33,7 @@
 #define __MLX5_EN_XDP_H__
 
 #include <linux/indirect_call_wrapper.h>
+#include <net/xdp_sock_drv.h>
 
 #include "en.h"
 #include "en/txrx.h"
@@ -112,6 +113,21 @@ static inline void mlx5e_xmit_xdp_doorbell(struct mlx5e_xdpsq *sq)
 	}
 }
 
+static inline struct mlx5e_xdp_buff *mlx5e_xsk_buff_alloc(struct xsk_buff_pool *pool)
+{
+	return (struct mlx5e_xdp_buff *)xsk_buff_alloc(pool);
+}
+
+static inline void mlx5e_xsk_buff_free(struct mlx5e_xdp_buff *mxbuf)
+{
+	xsk_buff_free(&mxbuf->xdp);
+}
+
+static inline dma_addr_t mlx5e_xsk_buff_xdp_get_frame_dma(struct mlx5e_xdp_buff *mxbuf)
+{
+	return xsk_buff_xdp_get_frame_dma(&mxbuf->xdp);
+}
+
 /* Enable inline WQEs to shift some load from a congested HCA (HW) to
  * a less congested cpu (SW).
  */
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
index 8bf3029abd3c..1f166dbb7f22 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/rx.c
@@ -3,7 +3,6 @@
 
 #include "rx.h"
 #include "en/xdp.h"
-#include <net/xdp_sock_drv.h>
 #include <linux/filter.h>
 
 /* RX data path */
@@ -21,7 +20,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 	if (unlikely(!xsk_buff_can_alloc(rq->xsk_pool, rq->mpwqe.pages_per_wqe)))
 		goto err;
 
-	BUILD_BUG_ON(sizeof(wi->alloc_units[0]) != sizeof(wi->alloc_units[0].xsk));
+	BUILD_BUG_ON(sizeof(wi->alloc_units[0]) != sizeof(wi->alloc_units[0].mxbuf));
 	XSK_CHECK_PRIV_TYPE(struct mlx5e_xdp_buff);
 	batch = xsk_buff_alloc_batch(rq->xsk_pool, (struct xdp_buff **)wi->alloc_units,
 				     rq->mpwqe.pages_per_wqe);
@@ -33,8 +32,8 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 	 * the first error, which will mean there are no more valid descriptors.
 	 */
 	for (; batch < rq->mpwqe.pages_per_wqe; batch++) {
-		wi->alloc_units[batch].xsk = xsk_buff_alloc(rq->xsk_pool);
-		if (unlikely(!wi->alloc_units[batch].xsk))
+		wi->alloc_units[batch].mxbuf = mlx5e_xsk_buff_alloc(rq->xsk_pool);
+		if (unlikely(!wi->alloc_units[batch].mxbuf))
 			goto err_reuse_batch;
 	}
 
@@ -44,7 +43,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 
 	if (likely(rq->mpwqe.umr_mode == MLX5E_MPWRQ_UMR_MODE_ALIGNED)) {
 		for (i = 0; i < batch; i++) {
-			dma_addr_t addr = xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].xsk);
+			dma_addr_t addr = mlx5e_xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].mxbuf);
 
 			umr_wqe->inline_mtts[i] = (struct mlx5_mtt) {
 				.ptag = cpu_to_be64(addr | MLX5_EN_WR),
@@ -53,7 +52,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 		}
 	} else if (unlikely(rq->mpwqe.umr_mode == MLX5E_MPWRQ_UMR_MODE_UNALIGNED)) {
 		for (i = 0; i < batch; i++) {
-			dma_addr_t addr = xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].xsk);
+			dma_addr_t addr = mlx5e_xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].mxbuf);
 
 			umr_wqe->inline_ksms[i] = (struct mlx5_ksm) {
 				.key = rq->mkey_be,
@@ -65,7 +64,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 		u32 mapping_size = 1 << (rq->mpwqe.page_shift - 2);
 
 		for (i = 0; i < batch; i++) {
-			dma_addr_t addr = xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].xsk);
+			dma_addr_t addr = mlx5e_xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].mxbuf);
 
 			umr_wqe->inline_ksms[i << 2] = (struct mlx5_ksm) {
 				.key = rq->mkey_be,
@@ -91,7 +90,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 		__be32 frame_size = cpu_to_be32(rq->xsk_pool->chunk_size);
 
 		for (i = 0; i < batch; i++) {
-			dma_addr_t addr = xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].xsk);
+			dma_addr_t addr = mlx5e_xsk_buff_xdp_get_frame_dma(wi->alloc_units[i].mxbuf);
 
 			umr_wqe->inline_klms[i << 1] = (struct mlx5_klm) {
 				.key = rq->mkey_be,
@@ -137,7 +136,7 @@ int mlx5e_xsk_alloc_rx_mpwqe(struct mlx5e_rq *rq, u16 ix)
 
 err_reuse_batch:
 	while (--batch >= 0)
-		xsk_buff_free(wi->alloc_units[batch].xsk);
+		mlx5e_xsk_buff_free(wi->alloc_units[batch].mxbuf);
 
 err:
 	rq->stats->buff_alloc_err++;
@@ -156,7 +155,7 @@ int mlx5e_xsk_alloc_rx_wqes_batched(struct mlx5e_rq *rq, u16 ix, int wqe_bulk)
 	 * allocate XDP buffers straight into alloc_units.
 	 */
 	BUILD_BUG_ON(sizeof(rq->wqe.alloc_units[0]) !=
-		     sizeof(rq->wqe.alloc_units[0].xsk));
+		     sizeof(rq->wqe.alloc_units[0].mxbuf));
 	buffs = (struct xdp_buff **)rq->wqe.alloc_units;
 	contig = mlx5_wq_cyc_get_size(wq) - ix;
 	if (wqe_bulk <= contig) {
@@ -177,8 +176,9 @@ int mlx5e_xsk_alloc_rx_wqes_batched(struct mlx5e_rq *rq, u16 ix, int wqe_bulk)
 		/* Assumes log_num_frags == 0. */
 		frag = &rq->wqe.frags[j];
 
-		addr = xsk_buff_xdp_get_frame_dma(frag->au->xsk);
+		addr = mlx5e_xsk_buff_xdp_get_frame_dma(frag->au->mxbuf);
 		wqe->data[0].addr = cpu_to_be64(addr + rq->buff.headroom);
+		frag->au->mxbuf->rq = rq;
 	}
 
 	return alloc;
@@ -199,12 +199,13 @@ int mlx5e_xsk_alloc_rx_wqes(struct mlx5e_rq *rq, u16 ix, int wqe_bulk)
 		/* Assumes log_num_frags == 0. */
 		frag = &rq->wqe.frags[j];
 
-		frag->au->xsk = xsk_buff_alloc(rq->xsk_pool);
-		if (unlikely(!frag->au->xsk))
+		frag->au->mxbuf = mlx5e_xsk_buff_alloc(rq->xsk_pool);
+		if (unlikely(!frag->au->mxbuf))
 			return i;
 
-		addr = xsk_buff_xdp_get_frame_dma(frag->au->xsk);
+		addr = mlx5e_xsk_buff_xdp_get_frame_dma(frag->au->mxbuf);
 		wqe->data[0].addr = cpu_to_be64(addr + rq->buff.headroom);
+		frag->au->mxbuf->rq = rq;
 	}
 
 	return wqe_bulk;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 7b08653be000..4313165709cb 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -41,7 +41,6 @@
 #include <net/gro.h>
 #include <net/udp.h>
 #include <net/tcp.h>
-#include <net/xdp_sock_drv.h>
 #include "en.h"
 #include "en/txrx.h"
 #include "en_tc.h"
@@ -434,7 +433,7 @@ static inline void mlx5e_free_rx_wqe(struct mlx5e_rq *rq,
 		 * put into the Reuse Ring, because there is no way to return
 		 * the page to the userspace when the interface goes down.
 		 */
-		xsk_buff_free(wi->au->xsk);
+		mlx5e_xsk_buff_free(wi->au->mxbuf);
 		return;
 	}
 
@@ -515,7 +514,7 @@ mlx5e_free_rx_mpwqe(struct mlx5e_rq *rq, struct mlx5e_mpw_info *wi, bool recycle
 		 */
 		for (i = 0; i < rq->mpwqe.pages_per_wqe; i++)
 			if (no_xdp_xmit || !test_bit(i, wi->xdp_xmit_bitmap))
-				xsk_buff_free(alloc_units[i].xsk);
+				mlx5e_xsk_buff_free(alloc_units[i].mxbuf);
 	} else {
 		for (i = 0; i < rq->mpwqe.pages_per_wqe; i++)
 			if (no_xdp_xmit || !test_bit(i, wi->xdp_xmit_bitmap))