From 4c805f7ae1ce61a90121378a5ee1f47b3b870c73 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Thu, 12 Jun 2025 18:02:27 +0200 Subject: [PATCH] libeth: xdp: add XDP prog run and verdict result handling Running a prog and handling the verdicts, up to napi_gro_receive() is also pretty generic code not really differing between vendors (except for Tx descriptor filling and Rx descriptor parsing). Define a couple inlines to do that. The inline callbacks a driver needs to pass is mentioned above: Tx descriptor filling for XDP_TX, populating skb with the descriptor data for XDP_PASS, finalizing XDPSQs after the polling loop for XDP_TX (kicking the HW to start sending). The populate callback passes only &libeth_xdp_buff assuming buff::desc pointer is enough, plus you can always get the corresponding Rx queue structure via container_of(buff::rxq). If not, a driver can extend the buff with more fields directly on the stack without touching libeth_xdp definitions. Signed-off-by: Alexander Lobakin Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/libeth/xdp.c | 27 +++ include/net/libeth/types.h | 22 ++ include/net/libeth/xdp.h | 281 ++++++++++++++++++++++++ 3 files changed, 330 insertions(+) diff --git a/drivers/net/ethernet/intel/libeth/xdp.c b/drivers/net/ethernet/intel/libeth/xdp.c index d0669f1f02f37..1607579d65bb7 100644 --- a/drivers/net/ethernet/intel/libeth/xdp.c +++ b/drivers/net/ethernet/intel/libeth/xdp.c @@ -277,6 +277,33 @@ recycle: } EXPORT_SYMBOL_GPL(libeth_xdp_buff_add_frag); +/** + * libeth_xdp_prog_exception - handle XDP prog exceptions + * @bq: XDP Tx bulk + * @xdp: buffer to process + * @act: original XDP prog verdict + * @ret: error code if redirect failed + * + * External helper used by __libeth_xdp_run_prog(), do not call directly. + * Reports invalid @act, XDP exception trace event and frees the buffer. + * + * Return: libeth_xdp XDP prog verdict. + */ +u32 __cold libeth_xdp_prog_exception(const struct libeth_xdp_tx_bulk *bq, + struct libeth_xdp_buff *xdp, + enum xdp_action act, int ret) +{ + if (act > XDP_REDIRECT) + bpf_warn_invalid_xdp_action(bq->dev, bq->prog, act); + + libeth_trace_xdp_exception(bq->dev, bq->prog, act); + + libeth_xdp_return_buff_slow(xdp); + + return LIBETH_XDP_DROP; +} +EXPORT_SYMBOL_GPL(libeth_xdp_prog_exception); + /* Tx buffer completion */ static void libeth_xdp_put_netmem_bulk(netmem_ref netmem, diff --git a/include/net/libeth/types.h b/include/net/libeth/types.h index 7b27c1966d45b..cf1d78a9dc381 100644 --- a/include/net/libeth/types.h +++ b/include/net/libeth/types.h @@ -6,6 +6,28 @@ #include +/* Stats */ + +/** + * struct libeth_rq_napi_stats - "hot" counters to update in Rx polling loop + * @packets: received frames counter + * @bytes: sum of bytes of received frames above + * @fragments: sum of fragments of received S/G frames + * @hsplit: number of frames the device performed the header split for + * @raw: alias to access all the fields as an array + */ +struct libeth_rq_napi_stats { + union { + struct { + u32 packets; + u32 bytes; + u32 fragments; + u32 hsplit; + }; + DECLARE_FLEX_ARRAY(u32, raw); + }; +}; + /** * struct libeth_sq_napi_stats - "hot" counters to update in Tx completion loop * @packets: completed frames counter diff --git a/include/net/libeth/xdp.h b/include/net/libeth/xdp.h index 780447cdabc1b..db99bc690eb60 100644 --- a/include/net/libeth/xdp.h +++ b/include/net/libeth/xdp.h @@ -20,6 +20,7 @@ enum { LIBETH_XDP_DROP = BIT(0), LIBETH_XDP_ABORTED = BIT(1), LIBETH_XDP_TX = BIT(2), + LIBETH_XDP_REDIRECT = BIT(3), }; /* @@ -353,6 +354,7 @@ static_assert(offsetof(struct libeth_xdp_tx_frame, frag.len) == * @prog: corresponding active XDP program, %NULL for .ndo_xdp_xmit() * @dev: &net_device which the frames are transmitted on * @xdpsq: shortcut to the corresponding driver-specific XDPSQ structure + * @act_mask: Rx only, mask of all the XDP prog verdicts for that NAPI session * @count: current number of frames in @bulk * @bulk: array of queued frames for bulk Tx * @@ -366,6 +368,7 @@ struct libeth_xdp_tx_bulk { struct net_device *dev; void *xdpsq; + u32 act_mask; u32 count; struct libeth_xdp_tx_frame bulk[LIBETH_XDP_TX_BULK]; } __aligned(sizeof(struct libeth_xdp_tx_frame)); @@ -999,6 +1002,40 @@ __libeth_xdp_xmit_do_bulk(struct libeth_xdp_tx_bulk *bq, /* Rx polling path */ +/** + * libeth_xdp_tx_init_bulk - initialize an XDP Tx bulk for Rx NAPI poll + * @bq: bulk to initialize + * @prog: RCU pointer to the XDP program (can be %NULL) + * @dev: target &net_device + * @xdpsqs: array of driver XDPSQ structs + * @num: number of active XDPSQs, the above array length + * + * Should be called on an onstack XDP Tx bulk before the NAPI polling loop. + * Initializes all the needed fields to run libeth_xdp functions. If @num == 0, + * assumes XDP is not enabled. + */ +#define libeth_xdp_tx_init_bulk(bq, prog, dev, xdpsqs, num) \ + __libeth_xdp_tx_init_bulk(bq, prog, dev, xdpsqs, num, false, \ + __UNIQUE_ID(bq_), __UNIQUE_ID(nqs_)) + +#define __libeth_xdp_tx_init_bulk(bq, pr, d, xdpsqs, num, ub, un) do { \ + typeof(bq) ub = (bq); \ + u32 un = (num); \ + \ + rcu_read_lock(); \ + \ + if (un) { \ + ub->prog = rcu_dereference(pr); \ + ub->dev = (d); \ + ub->xdpsq = (xdpsqs)[libeth_xdpsq_id(un)]; \ + } else { \ + ub->prog = NULL; \ + } \ + \ + ub->act_mask = 0; \ + ub->count = 0; \ +} while (0) + void libeth_xdp_load_stash(struct libeth_xdp_buff *dst, const struct libeth_xdp_buff_stash *src); void libeth_xdp_save_stash(struct libeth_xdp_buff_stash *dst, @@ -1155,6 +1192,250 @@ static inline bool libeth_xdp_process_buff(struct libeth_xdp_buff *xdp, return true; } +/** + * libeth_xdp_buff_stats_frags - update onstack RQ stats with XDP frags info + * @ss: onstack stats to update + * @xdp: buffer to account + * + * Internal helper used by __libeth_xdp_run_pass(), do not call directly. + * Adds buffer's frags count and total len to the onstack stats. + */ +static inline void +libeth_xdp_buff_stats_frags(struct libeth_rq_napi_stats *ss, + const struct libeth_xdp_buff *xdp) +{ + const struct skb_shared_info *sinfo; + + sinfo = xdp_get_shared_info_from_buff(&xdp->base); + ss->bytes += sinfo->xdp_frags_size; + ss->fragments += sinfo->nr_frags + 1; +} + +u32 libeth_xdp_prog_exception(const struct libeth_xdp_tx_bulk *bq, + struct libeth_xdp_buff *xdp, + enum xdp_action act, int ret); + +/** + * __libeth_xdp_run_prog - run XDP program on an XDP buffer + * @xdp: XDP buffer to run the prog on + * @bq: buffer bulk for ``XDP_TX`` queueing + * + * Internal inline abstraction to run XDP program. Handles ``XDP_DROP`` + * and ``XDP_REDIRECT`` only, the rest is processed levels up. + * Reports an XDP prog exception on errors. + * + * Return: libeth_xdp prog verdict depending on the prog's verdict. + */ +static __always_inline u32 +__libeth_xdp_run_prog(struct libeth_xdp_buff *xdp, + const struct libeth_xdp_tx_bulk *bq) +{ + enum xdp_action act; + + act = bpf_prog_run_xdp(bq->prog, &xdp->base); + if (unlikely(act < XDP_DROP || act > XDP_REDIRECT)) + goto out; + + switch (act) { + case XDP_PASS: + return LIBETH_XDP_PASS; + case XDP_DROP: + libeth_xdp_return_buff(xdp); + + return LIBETH_XDP_DROP; + case XDP_TX: + return LIBETH_XDP_TX; + case XDP_REDIRECT: + if (unlikely(xdp_do_redirect(bq->dev, &xdp->base, bq->prog))) + break; + + xdp->data = NULL; + + return LIBETH_XDP_REDIRECT; + default: + break; + } + +out: + return libeth_xdp_prog_exception(bq, xdp, act, 0); +} + +/** + * __libeth_xdp_run_flush - run XDP program and handle ``XDP_TX`` verdict + * @xdp: XDP buffer to run the prog on + * @bq: buffer bulk for ``XDP_TX`` queueing + * @run: internal callback for running XDP program + * @queue: internal callback for queuing ``XDP_TX`` frame + * @flush_bulk: driver callback for flushing a bulk + * + * Internal inline abstraction to run XDP program and additionally handle + * ``XDP_TX`` verdict. + * Do not use directly. + * + * Return: libeth_xdp prog verdict depending on the prog's verdict. + */ +static __always_inline u32 +__libeth_xdp_run_flush(struct libeth_xdp_buff *xdp, + struct libeth_xdp_tx_bulk *bq, + u32 (*run)(struct libeth_xdp_buff *xdp, + const struct libeth_xdp_tx_bulk *bq), + bool (*queue)(struct libeth_xdp_tx_bulk *bq, + struct libeth_xdp_buff *xdp, + bool (*flush_bulk) + (struct libeth_xdp_tx_bulk *bq, + u32 flags)), + bool (*flush_bulk)(struct libeth_xdp_tx_bulk *bq, + u32 flags)) +{ + u32 act; + + act = run(xdp, bq); + if (act == LIBETH_XDP_TX && unlikely(!queue(bq, xdp, flush_bulk))) + act = LIBETH_XDP_DROP; + + bq->act_mask |= act; + + return act; +} + +/** + * libeth_xdp_run_prog - run XDP program and handle all verdicts + * @xdp: XDP buffer to process + * @bq: XDP Tx bulk to queue ``XDP_TX`` buffers + * @fl: driver ``XDP_TX`` bulk flush callback + * + * Run the attached XDP program and handle all possible verdicts. + * + * Return: true if the buffer should be passed up the stack, false if the poll + * should go to the next buffer. + */ +#define libeth_xdp_run_prog(xdp, bq, fl) \ + (__libeth_xdp_run_flush(xdp, bq, __libeth_xdp_run_prog, \ + libeth_xdp_tx_queue_bulk, \ + fl) == LIBETH_XDP_PASS) + +/** + * __libeth_xdp_run_pass - helper to run XDP program and handle the result + * @xdp: XDP buffer to process + * @bq: XDP Tx bulk to queue ``XDP_TX`` frames + * @napi: NAPI to build an skb and pass it up the stack + * @rs: onstack libeth RQ stats + * @md: metadata that should be filled to the XDP buffer + * @prep: callback for filling the metadata + * @run: driver wrapper to run XDP program + * @populate: driver callback to populate an skb with the HW descriptor data + * + * Inline abstraction that does the following: + * 1) adds frame size and frag number (if needed) to the onstack stats; + * 2) fills the descriptor metadata to the onstack &libeth_xdp_buff + * 3) runs XDP program if present; + * 4) handles all possible verdicts; + * 5) on ``XDP_PASS`, builds an skb from the buffer; + * 6) populates it with the descriptor metadata; + * 7) passes it up the stack. + * + * In most cases, number 2 means just writing the pointer to the HW descriptor + * to the XDP buffer. If so, please use LIBETH_XDP_DEFINE_RUN{,_PASS}() + * wrappers to build a driver function. + */ +static __always_inline void +__libeth_xdp_run_pass(struct libeth_xdp_buff *xdp, + struct libeth_xdp_tx_bulk *bq, struct napi_struct *napi, + struct libeth_rq_napi_stats *rs, const void *md, + void (*prep)(struct libeth_xdp_buff *xdp, + const void *md), + bool (*run)(struct libeth_xdp_buff *xdp, + struct libeth_xdp_tx_bulk *bq), + bool (*populate)(struct sk_buff *skb, + const struct libeth_xdp_buff *xdp, + struct libeth_rq_napi_stats *rs)) +{ + struct sk_buff *skb; + + rs->bytes += xdp->base.data_end - xdp->data; + rs->packets++; + + if (xdp_buff_has_frags(&xdp->base)) + libeth_xdp_buff_stats_frags(rs, xdp); + + if (prep && (!__builtin_constant_p(!!md) || md)) + prep(xdp, md); + + if (!bq || !run || !bq->prog) + goto build; + + if (!run(xdp, bq)) + return; + +build: + skb = xdp_build_skb_from_buff(&xdp->base); + if (unlikely(!skb)) { + libeth_xdp_return_buff_slow(xdp); + return; + } + + xdp->data = NULL; + + if (unlikely(!populate(skb, xdp, rs))) { + napi_consume_skb(skb, true); + return; + } + + napi_gro_receive(napi, skb); +} + +static inline void libeth_xdp_prep_desc(struct libeth_xdp_buff *xdp, + const void *desc) +{ + xdp->desc = desc; +} + +/** + * libeth_xdp_run_pass - helper to run XDP program and handle the result + * @xdp: XDP buffer to process + * @bq: XDP Tx bulk to queue ``XDP_TX`` frames + * @napi: NAPI to build an skb and pass it up the stack + * @ss: onstack libeth RQ stats + * @desc: pointer to the HW descriptor for that frame + * @run: driver wrapper to run XDP program + * @populate: driver callback to populate an skb with the HW descriptor data + * + * Wrapper around the underscored version when "fill the descriptor metadata" + * means just writing the pointer to the HW descriptor as @xdp->desc. + */ +#define libeth_xdp_run_pass(xdp, bq, napi, ss, desc, run, populate) \ + __libeth_xdp_run_pass(xdp, bq, napi, ss, desc, libeth_xdp_prep_desc, \ + run, populate) + +/** + * libeth_xdp_finalize_rx - finalize XDPSQ after a NAPI polling loop + * @bq: ``XDP_TX`` frame bulk + * @flush: driver callback to flush the bulk + * @finalize: driver callback to start sending the frames and run the timer + * + * Flush the bulk if there are frames left to send, kick the queue and flush + * the XDP maps. + */ +#define libeth_xdp_finalize_rx(bq, flush, finalize) \ + __libeth_xdp_finalize_rx(bq, 0, flush, finalize) + +static __always_inline void +__libeth_xdp_finalize_rx(struct libeth_xdp_tx_bulk *bq, u32 flags, + bool (*flush_bulk)(struct libeth_xdp_tx_bulk *bq, + u32 flags), + void (*finalize)(void *xdpsq, bool sent, bool flush)) +{ + if (bq->act_mask & LIBETH_XDP_TX) { + if (bq->count) + flush_bulk(bq, flags | LIBETH_XDP_TX_DROP); + finalize(bq->xdpsq, true, true); + } + if (bq->act_mask & LIBETH_XDP_REDIRECT) + xdp_do_flush(); + + rcu_read_unlock(); +} + /* Tx buffer completion */ void libeth_xdp_return_buff_bulk(const struct skb_shared_info *sinfo, -- 2.47.2