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Message-ID: <ZVYQiAhahijwfN+w@boxer>
Date: Thu, 16 Nov 2023 13:52:24 +0100
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: Larysa Zaremba <larysa.zaremba@...el.com>
CC: <bpf@...r.kernel.org>, <ast@...nel.org>, <daniel@...earbox.net>,
<andrii@...nel.org>, <martin.lau@...ux.dev>, <song@...nel.org>, <yhs@...com>,
<john.fastabend@...il.com>, <kpsingh@...nel.org>, <sdf@...gle.com>,
<haoluo@...gle.com>, <jolsa@...nel.org>, David Ahern <dsahern@...il.com>,
Jakub Kicinski <kuba@...nel.org>, Willem de Bruijn <willemb@...gle.com>,
Jesper Dangaard Brouer <hawk@...nel.org>, Anatoly Burakov
<anatoly.burakov@...el.com>, Alexander Lobakin <alexandr.lobakin@...el.com>,
Magnus Karlsson <magnus.karlsson@...il.com>, Maryam Tahhan
<mtahhan@...hat.com>, <xdp-hints@...-project.net>, <netdev@...r.kernel.org>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>, Alexei Starovoitov
<alexei.starovoitov@...il.com>, Tariq Toukan <tariqt@...lanox.com>, "Saeed
Mahameed" <saeedm@...lanox.com>
Subject: Re: [PATCH bpf-next v7 04/18] ice: Introduce ice_xdp_buff
On Wed, Nov 15, 2023 at 06:52:46PM +0100, Larysa Zaremba wrote:
> In order to use XDP hints via kfuncs we need to put
> RX descriptor and miscellaneous data next to xdp_buff.
> Same as in hints implementations in other drivers, we achieve
> this through putting xdp_buff into a child structure.
>
> Currently, xdp_buff is stored in the ring structure,
> so replace it with union that includes child structure.
> This way enough memory is available while existing XDP code
> remains isolated from hints.
>
> Minimum size of the new child structure (ice_xdp_buff) is exactly
> 64 bytes (single cache line). To place it at the start of a cache line,
> move 'next' field from CL1 to CL4, as it isn't used often. This still
> leaves 192 bits available in CL3 for packet context extensions.
>
> Signed-off-by: Larysa Zaremba <larysa.zaremba@...el.com>
> ---
> drivers/net/ethernet/intel/ice/ice_txrx.c | 7 +++++--
> drivers/net/ethernet/intel/ice/ice_txrx.h | 18 +++++++++++++++---
> drivers/net/ethernet/intel/ice/ice_txrx_lib.h | 10 ++++++++++
> 3 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
> index 40f2f6dabb81..4e6546d9cf85 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx.c
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx.c
> @@ -557,13 +557,14 @@ ice_rx_frame_truesize(struct ice_rx_ring *rx_ring, const unsigned int size)
> * @xdp_prog: XDP program to run
> * @xdp_ring: ring to be used for XDP_TX action
> * @rx_buf: Rx buffer to store the XDP action
> + * @eop_desc: Last descriptor in packet to read metadata from
> *
> * Returns any of ICE_XDP_{PASS, CONSUMED, TX, REDIR}
> */
> static void
> ice_run_xdp(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
> struct bpf_prog *xdp_prog, struct ice_tx_ring *xdp_ring,
> - struct ice_rx_buf *rx_buf)
> + struct ice_rx_buf *rx_buf, union ice_32b_rx_flex_desc *eop_desc)
> {
> unsigned int ret = ICE_XDP_PASS;
> u32 act;
> @@ -571,6 +572,8 @@ ice_run_xdp(struct ice_rx_ring *rx_ring, struct xdp_buff *xdp,
> if (!xdp_prog)
> goto exit;
>
> + ice_xdp_meta_set_desc(xdp, eop_desc);
> +
> act = bpf_prog_run_xdp(xdp_prog, xdp);
> switch (act) {
> case XDP_PASS:
> @@ -1240,7 +1243,7 @@ int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget)
> if (ice_is_non_eop(rx_ring, rx_desc))
> continue;
>
> - ice_run_xdp(rx_ring, xdp, xdp_prog, xdp_ring, rx_buf);
> + ice_run_xdp(rx_ring, xdp, xdp_prog, xdp_ring, rx_buf, rx_desc);
> if (rx_buf->act == ICE_XDP_PASS)
> goto construct_skb;
> total_rx_bytes += xdp_get_buff_len(xdp);
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.h b/drivers/net/ethernet/intel/ice/ice_txrx.h
> index 166413fc33f4..9efb42f99415 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx.h
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx.h
> @@ -257,6 +257,14 @@ enum ice_rx_dtype {
> ICE_RX_DTYPE_SPLIT_ALWAYS = 2,
> };
>
> +struct ice_xdp_buff {
> + struct xdp_buff xdp_buff;
> + const union ice_32b_rx_flex_desc *eop_desc;
> +};
> +
> +/* Required for compatibility with xdp_buffs from xsk_pool */
> +static_assert(offsetof(struct ice_xdp_buff, xdp_buff) == 0);
That should go to xsk core as a macro and should be used by ZC drivers
that support hints. Useful stuff similar to XSK_CEHCK_PRIV_TYPE() but
check is from the other end.
> +
> /* indices into GLINT_ITR registers */
> #define ICE_RX_ITR ICE_IDX_ITR0
> #define ICE_TX_ITR ICE_IDX_ITR1
> @@ -298,7 +306,6 @@ enum ice_dynamic_itr {
> /* descriptor ring, associated with a VSI */
> struct ice_rx_ring {
> /* CL1 - 1st cacheline starts here */
> - struct ice_rx_ring *next; /* pointer to next ring in q_vector */
> void *desc; /* Descriptor ring memory */
> struct device *dev; /* Used for DMA mapping */
> struct net_device *netdev; /* netdev ring maps to */
> @@ -310,12 +317,16 @@ struct ice_rx_ring {
> u16 count; /* Number of descriptors */
> u16 reg_idx; /* HW register index of the ring */
> u16 next_to_alloc;
> - /* CL2 - 2nd cacheline starts here */
> +
> union {
> struct ice_rx_buf *rx_buf;
> struct xdp_buff **xdp_buf;
> };
> - struct xdp_buff xdp;
> + /* CL2 - 2nd cacheline starts here */
> + union {
> + struct ice_xdp_buff xdp_ext;
> + struct xdp_buff xdp;
> + };
> /* CL3 - 3rd cacheline starts here */
> struct bpf_prog *xdp_prog;
> u16 rx_offset;
> @@ -332,6 +343,7 @@ struct ice_rx_ring {
> /* CL4 - 4th cacheline starts here */
> struct ice_channel *ch;
> struct ice_tx_ring *xdp_ring;
> + struct ice_rx_ring *next; /* pointer to next ring in q_vector */
> struct xsk_buff_pool *xsk_pool;
> dma_addr_t dma; /* physical address of ring */
> u64 cached_phctime;
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.h b/drivers/net/ethernet/intel/ice/ice_txrx_lib.h
> index e1d49e1235b3..81b8856d8e13 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx_lib.h
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx_lib.h
> @@ -151,4 +151,14 @@ ice_process_skb_fields(struct ice_rx_ring *rx_ring,
> struct sk_buff *skb);
> void
> ice_receive_skb(struct ice_rx_ring *rx_ring, struct sk_buff *skb, u16 vlan_tag);
> +
> +static inline void
> +ice_xdp_meta_set_desc(struct xdp_buff *xdp,
> + union ice_32b_rx_flex_desc *eop_desc)
> +{
> + struct ice_xdp_buff *xdp_ext = container_of(xdp, struct ice_xdp_buff,
> + xdp_buff);
> +
> + xdp_ext->eop_desc = eop_desc;
> +}
> #endif /* !_ICE_TXRX_LIB_H_ */
> --
> 2.41.0
>
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