linux-kernel - Re: [PATCH net-next v1] idpf: export RX hardware timestamping information to XDP

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Message-ID: <c2580ef0-3e44-468d-8675-203de5c82ac9@intel.com>
Date: Wed, 17 Dec 2025 15:33:40 +0100
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Mina Almasry <almasrymina@...gle.com>
CC: <netdev@...r.kernel.org>, <bpf@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, 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>, Tony Nguyen
	<anthony.l.nguyen@...el.com>, Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>, Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>, Richard Cochran <richardcochran@...il.com>,
	<intel-wired-lan@...ts.osuosl.org>
Subject: Re: [PATCH net-next v1] idpf: export RX hardware timestamping
 information to XDP

From: Mina Almasry <almasrymina@...gle.com>
Date: Sat, 22 Nov 2025 14:08:36 +0000

> 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;

Sorry I know it's a late comment...

Could you please you the optimized descriptor structure from idpf/xdp.h
instead of the regular one? To be consistent with the Rx hash timestamp
function and give more room for optimization.

> +	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;
> +
> +	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

Thanks,
Olek