linux-kernel - RE: [Intel-wired-lan] [PATCH net-next v1] idpf: export RX hardware timestamping information to XDP

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Message-ID: <DS4PPF7551E6552ECCF95AE9C177DEF07F8E5D0A@DS4PPF7551E6552.namprd11.prod.outlook.com>
Date: Mon, 24 Nov 2025 08:33:00 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: Mina Almasry <almasrymina@...gle.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: YiFei Zhu <zhuyifei@...gle.com>, Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>, "David S. Miller"
	<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, "Jesper Dangaard
 Brouer" <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>,
	Stanislav Fomichev <sdf@...ichev.me>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, Andrew Lunn <andrew+netdev@...n.ch>, "Eric
 Dumazet" <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, "Lobakin,
 Aleksander" <aleksander.lobakin@...el.com>, Richard Cochran
	<richardcochran@...il.com>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>
Subject: RE: [Intel-wired-lan] [PATCH net-next v1] idpf: export RX hardware
 timestamping information to XDP



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> Of Mina Almasry
> Sent: Saturday, November 22, 2025 3:09 PM
> To: netdev@...r.kernel.org; bpf@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Cc: YiFei Zhu <zhuyifei@...gle.com>; Alexei Starovoitov
> <ast@...nel.org>; Daniel Borkmann <daniel@...earbox.net>; David S.
> Miller <davem@...emloft.net>; Jakub Kicinski <kuba@...nel.org>; Jesper
> Dangaard Brouer <hawk@...nel.org>; John Fastabend
> <john.fastabend@...il.com>; Stanislav Fomichev <sdf@...ichev.me>;
> Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@...el.com>; Andrew Lunn <andrew+netdev@...n.ch>;
> Eric Dumazet <edumazet@...gle.com>; Paolo Abeni <pabeni@...hat.com>;
> Lobakin, Aleksander <aleksander.lobakin@...el.com>; Richard Cochran
> <richardcochran@...il.com>; intel-wired-lan@...ts.osuosl.org; Mina
> Almasry <almasrymina@...gle.com>
> Subject: [Intel-wired-lan] [PATCH net-next v1] idpf: export RX
> hardware timestamping information to XDP
> 
> From: YiFei Zhu <zhuyifei@...gle.com>
> 
> The logic is similar to idpf_rx_hwtstamp, but the data is exported as
> a BPF kfunc instead of appended to an skb.
> 
> A idpf_queue_has(PTP, rxq) condition is added to check the queue
> supports PTP similar to idpf_rx_process_skb_fields.
> 
> Cc: intel-wired-lan@...ts.osuosl.org
> 
> Signed-off-by: YiFei Zhu <zhuyifei@...gle.com>
> Signed-off-by: Mina Almasry <almasrymina@...gle.com>
> ---
>  drivers/net/ethernet/intel/idpf/xdp.c | 27
> +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/xdp.c
> b/drivers/net/ethernet/intel/idpf/xdp.c
> index 21ce25b0567f..850389ca66b6 100644
> --- a/drivers/net/ethernet/intel/idpf/xdp.c
> +++ b/drivers/net/ethernet/intel/idpf/xdp.c
> @@ -2,6 +2,7 @@
>  /* Copyright (C) 2025 Intel Corporation */
> 
>  #include "idpf.h"
> +#include "idpf_ptp.h"
>  #include "idpf_virtchnl.h"
>  #include "xdp.h"
>  #include "xsk.h"
> @@ -369,6 +370,31 @@ int idpf_xdp_xmit(struct net_device *dev, int n,
> struct xdp_frame **frames,
>  				       idpf_xdp_tx_finalize);
>  }
> 
> +static int idpf_xdpmo_rx_timestamp(const struct xdp_md *ctx, u64
> +*timestamp) {
> +	const struct virtchnl2_rx_flex_desc_adv_nic_3 *rx_desc;
> +	const struct libeth_xdp_buff *xdp = (typeof(xdp))ctx;
> +	const struct idpf_rx_queue *rxq;
> +	u64 cached_time, ts_ns;
> +	u32 ts_high;
> +
> +	rx_desc = xdp->desc;
> +	rxq = libeth_xdp_buff_to_rq(xdp, typeof(*rxq), xdp_rxq);
> +
> +	if (!idpf_queue_has(PTP, rxq))
> +		return -ENODATA;
> +	if (!(rx_desc->ts_low & VIRTCHNL2_RX_FLEX_TSTAMP_VALID))
> +		return -ENODATA;
RX flex desc fields are little‑endian.
You already convert ts_high with le32_to_cpu(), but test ts_low directly against the mask.
On big‑endian this can misdetect the bit and spuriously return -ENODATA.
Please convert ts_low to host order before the bit test.
See existing IDPF/ICE patterns where descriptor words are leXX_to_cpu()‑converted prior to FIELD_GET() / bit checks.
Also, per the XDP RX metadata kfunc docs, -ENODATA must reflect true absence of per‑packet metadata; endianness‑correct testing is required to uphold the semantic.

> +
> +	cached_time = READ_ONCE(rxq->cached_phc_time);
> +
> +	ts_high = le32_to_cpu(rx_desc->ts_high);
> +	ts_ns = idpf_ptp_tstamp_extend_32b_to_64b(cached_time,
> ts_high);
> +
> +	*timestamp = ts_ns;
> +	return 0;
> +}
> +
>  static int idpf_xdpmo_rx_hash(const struct xdp_md *ctx, u32 *hash,
>  			      enum xdp_rss_hash_type *rss_type)  { @@ -
> 392,6 +418,7 @@ static int idpf_xdpmo_rx_hash(const struct xdp_md
> *ctx, u32 *hash,  }
> 
>  static const struct xdp_metadata_ops idpf_xdpmo = {
> +	.xmo_rx_timestamp	= idpf_xdpmo_rx_timestamp,
>  	.xmo_rx_hash		= idpf_xdpmo_rx_hash,
>  };
> 
> 
> base-commit: e05021a829b834fecbd42b173e55382416571b2c
> --
> 2.52.0.rc2.455.g230fcf2819-goog