On Wed, Nov 15, 2023 at 06:52:50PM +0100, Larysa Zaremba wrote:
> In AF_XDP ZC, xdp_buff is not stored on ring,
> instead it is provided by xsk_buff_pool.
> Space for metadata sources right after such buffers was already reserved
> in commit 94ecc5ca4dbf ("xsk: Add cb area to struct xdp_buff_xsk").
>
> Some things (such as pointer to packet context) do not change on a
> per-packet basis, so they can be set at the same time as RX queue info.
> On the other hand, RX descriptor is unique for each packet, but is already
> known when setting DMA addresses. This minimizes performance impact of
> hints on regular packet processing.
>
> Update AF_XDP ZC packet processing to support XDP hints.
>
> Co-developed-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
> Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
> ---
> drivers/net/ethernet/intel/ice/ice_base.c | 13 +++++++++++++
> drivers/net/ethernet/intel/ice/ice_xsk.c | 17 +++++++++++------
> 2 files changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_base.c b/drivers/net/ethernet/intel/ice/ice_base.c
> index 2d83f3c029e7..d3396c1c87a9 100644
> --- a/drivers/net/ethernet/intel/ice/ice_base.c
> +++ b/drivers/net/ethernet/intel/ice/ice_base.c
> @@ -519,6 +519,18 @@ static int ice_setup_rx_ctx(struct ice_rx_ring *ring)
> return 0;
> }
>
> +static void ice_xsk_pool_fill_cb(struct ice_rx_ring *ring)
> +{
> + void *ctx_ptr = &ring->pkt_ctx;
> + struct xsk_cb_desc desc = {};
> +
> + desc.src = &ctx_ptr;
> + desc.off = offsetof(struct ice_xdp_buff, pkt_ctx) -
> + sizeof(struct xdp_buff);
Took me a while to figure out this offset calculation:D
> + desc.bytes = sizeof(ctx_ptr);
> + xsk_pool_fill_cb(ring->xsk_pool, &desc);
> +}
> +
> /**
> * ice_vsi_cfg_rxq - Configure an Rx queue
> * @ring: the ring being configured
> @@ -553,6 +565,7 @@ int ice_vsi_cfg_rxq(struct ice_rx_ring *ring)
> if (err)
> return err;
> xsk_pool_set_rxq_info(ring->xsk_pool, &ring->xdp_rxq);
A good place for XSK_CHECK_PRIV_TYPE() ?
> + ice_xsk_pool_fill_cb(ring);
>
> dev_info(dev, "Registered XDP mem model MEM_TYPE_XSK_BUFF_POOL on Rx ring %d\n",
> ring->q_index);
> diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
> index 906e383e864a..a690e34ea8ae 100644
> --- a/drivers/net/ethernet/intel/ice/ice_xsk.c
> +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
> @@ -433,7 +433,7 @@ int ice_xsk_pool_setup(struct ice_vsi *vsi, struct xsk_buff_pool *pool, u16 qid)
>
> /**
> * ice_fill_rx_descs - pick buffers from XSK buffer pool and use it
> - * @pool: XSK Buffer pool to pull the buffers from
> + * @rx_ring: rx ring
> * @xdp: SW ring of xdp_buff that will hold the buffers
> * @rx_desc: Pointer to Rx descriptors that will be filled
> * @count: The number of buffers to allocate
> @@ -445,19 +445,24 @@ int ice_xsk_pool_setup(struct ice_vsi *vsi, struct xsk_buff_pool *pool, u16 qid)
> *
> * Returns the amount of allocated Rx descriptors
> */
> -static u16 ice_fill_rx_descs(struct xsk_buff_pool *pool, struct xdp_buff **xdp,
> +static u16 ice_fill_rx_descs(struct ice_rx_ring *rx_ring, struct xdp_buff **xdp,
Might be lack of caffeine on my side, but I don't see a reason for passing
rx_ring down to ice_fill_rx_descs() ?
I see I introduced this in the code example previously but it must have
been some leftover from previous hacking...
Help!
> union ice_32b_rx_flex_desc *rx_desc, u16 count)
> {
> dma_addr_t dma;
> u16 buffs;
> int i;
>
> - buffs = xsk_buff_alloc_batch(pool, xdp, count);
> + buffs = xsk_buff_alloc_batch(rx_ring->xsk_pool, xdp, count);
> for (i = 0; i < buffs; i++) {
> dma = xsk_buff_xdp_get_dma(*xdp);
> rx_desc->read.pkt_addr = cpu_to_le64(dma);
> rx_desc->wb.status_error0 = 0;
>
> + /* Put private info that changes on a per-packet basis
> + * into xdp_buff_xsk->cb.
> + */
> + ice_xdp_meta_set_desc(*xdp, rx_desc);
> +
> rx_desc++;
> xdp++;
> }
> @@ -488,8 +493,7 @@ static bool __ice_alloc_rx_bufs_zc(struct ice_rx_ring *rx_ring, u16 count)
> xdp = ice_xdp_buf(rx_ring, ntu);
>
> if (ntu + count >= rx_ring->count) {
> - nb_buffs_extra = ice_fill_rx_descs(rx_ring->xsk_pool, xdp,
> - rx_desc,
> + nb_buffs_extra = ice_fill_rx_descs(rx_ring, xdp, rx_desc,
> rx_ring->count - ntu);
> if (nb_buffs_extra != rx_ring->count - ntu) {
> ntu += nb_buffs_extra;
> @@ -502,7 +506,7 @@ static bool __ice_alloc_rx_bufs_zc(struct ice_rx_ring *rx_ring, u16 count)
> ice_release_rx_desc(rx_ring, 0);
> }
>
> - nb_buffs = ice_fill_rx_descs(rx_ring->xsk_pool, xdp, rx_desc, count);
> + nb_buffs = ice_fill_rx_descs(rx_ring, xdp, rx_desc, count);
>
> ntu += nb_buffs;
> if (ntu == rx_ring->count)
> @@ -752,6 +756,7 @@ static int ice_xmit_xdp_tx_zc(struct xdp_buff *xdp,
> * @xdp: xdp_buff used as input to the XDP program
> * @xdp_prog: XDP program to run
> * @xdp_ring: ring to be used for XDP_TX action
> + * @rx_desc: packet descriptor
leftover comment from previous approach
> *
> * Returns any of ICE_XDP_{PASS, CONSUMED, TX, REDIR}
> */
> --
> 2.41.0
>
