netdev - Re: [PATCH net-next v2] idpf: export RX hardware timestamping information to XDP

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Message-ID: <73ab2fb8-6676-4d56-a512-24891191940a@intel.com>
Date: Thu, 18 Dec 2025 15:02:27 +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>, Aleksandr Loktionov
	<aleksandr.loktionov@...el.com>
Subject: Re: [PATCH net-next v2] idpf: export RX hardware timestamping
 information to XDP

From: Mina Almasry <almasrymina@...gle.com>
Date: Thu, 18 Dec 2025 02:29:36 +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.

Much better now, one nit below.

> 
> Cc: intel-wired-lan@...ts.osuosl.org
> 
> Signed-off-by: YiFei Zhu <zhuyifei@...gle.com>
> Signed-off-by: Mina Almasry <almasrymina@...gle.com>
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@...el.com>
> 
> ---
> 
> v2: https://lore.kernel.org/netdev/20251122140839.3922015-1-almasrymina@google.com/
> - Fixed alphabetical ordering
> - Use the xdp desc type instead of virtchnl one (required some added
>   helpers)
> 
> ---
>  drivers/net/ethernet/intel/idpf/xdp.c | 29 +++++++++++++++++++++++++++
>  drivers/net/ethernet/intel/idpf/xdp.h | 17 ++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/xdp.c b/drivers/net/ethernet/intel/idpf/xdp.c
> index 958d16f87424..7744d6898f74 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"
> @@ -391,8 +392,36 @@ static int idpf_xdpmo_rx_hash(const struct xdp_md *ctx, u32 *hash,
>  				    pt);
>  }
>  
> +static int idpf_xdpmo_rx_timestamp(const struct xdp_md *ctx, u64 *timestamp)
> +{
> +	const struct libeth_xdp_buff *xdp = (typeof(xdp))ctx;
> +	struct idpf_xdp_rx_desc desc __uninitialized;
> +	const struct idpf_rx_queue *rxq;
> +	u64 cached_time, ts_ns;
> +	u32 ts_high;
> +
> +	idpf_xdp_get_qw1(&desc, xdp->desc);
> +	rxq = libeth_xdp_buff_to_rq(xdp, typeof(*rxq), xdp_rxq);
> +
> +	if (!idpf_queue_has(PTP, rxq))
> +		return -ENODATA;

I think this could be optimized a little bit by reodering,

	rxq = libeth_xdp_buff_to_rq(xdp, typeof(*rxq), xdp_rxq);

	if (!idpf_queue_has(PTP, rxq))
		return -ENODATA;

	idpf_xdp_get_qw1(&desc, xdp->desc);

to not read the desc if the Rx queue doesn't have the PTP bit set.
Apart from this, LGTM.

> +	if (!(idpf_xdp_rx_ts_low(&desc) & VIRTCHNL2_RX_FLEX_TSTAMP_VALID))
> +		return -ENODATA;
> +
> +	cached_time = READ_ONCE(rxq->cached_phc_time);
> +
> +	idpf_xdp_get_qw3(&desc, xdp->desc);
> +
> +	ts_high = idpf_xdp_rx_ts_high(&desc);
> +	ts_ns = idpf_ptp_tstamp_extend_32b_to_64b(cached_time, ts_high);
> +
> +	*timestamp = ts_ns;
> +	return 0;
> +}
> +
>  static const struct xdp_metadata_ops idpf_xdpmo = {
>  	.xmo_rx_hash		= idpf_xdpmo_rx_hash,
> +	.xmo_rx_timestamp	= idpf_xdpmo_rx_timestamp,
>  };
Thanks,
Olek