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

[Stanislav Fomichev <sdf@google.com>]

On Thu, Jan 12, 2023 at 1:55 PM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Toke Høiland-Jørgensen <toke@redhat.com> writes:
>
> > Stanislav Fomichev <sdf@google.com> writes:
> >
> >> On Thu, Jan 12, 2023 at 12:07 AM Tariq Toukan <ttoukan.linux@gmail.com> wrote:
> >>>
> >>>
> >>>
> >>> On 12/01/2023 2:32, Stanislav Fomichev wrote:
> >>> > From: Toke Høiland-Jørgensen <toke@redhat.com>
> >>> >
> >>> > Preparation for implementing HW metadata kfuncs. No functional change.
> >>> >
> >>> > Cc: Tariq Toukan <tariqt@nvidia.com>
> >>> > Cc: Saeed Mahameed <saeedm@nvidia.com>
> >>> > Cc: John Fastabend <john.fastabend@gmail.com>
> >>> > Cc: David Ahern <dsahern@gmail.com>
> >>> > Cc: Martin KaFai Lau <martin.lau@linux.dev>
> >>> > Cc: Jakub Kicinski <kuba@kernel.org>
> >>> > Cc: Willem de Bruijn <willemb@google.com>
> >>> > Cc: Jesper Dangaard Brouer <brouer@redhat.com>
> >>> > Cc: Anatoly Burakov <anatoly.burakov@intel.com>
> >>> > Cc: Alexander Lobakin <alexandr.lobakin@intel.com>
> >>> > Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
> >>> > Cc: Maryam Tahhan <mtahhan@redhat.com>
> >>> > Cc: xdp-hints@xdp-project.net
> >>> > Cc: netdev@vger.kernel.org
> >>> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> >>> > Signed-off-by: Stanislav Fomichev <sdf@google.com>
> >>> > ---
> >>> >   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:

Seems more invasive? I don't care much tbf, but what's wrong with
keeping 'xdp_buff xsk' member and use it consistently?

> >> 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));
>         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))
>