Re: [PATCH net-next v3] idpf: export RX hardware timestamping information to XDP

[Alexander Lobakin <aleksander.lobakin@intel.com>]

From: Mina Almasry <almasrymina@google.com>
Date: Fri, 19 Dec 2025 20:29:54 +0000

> From: YiFei Zhu <zhuyifei@google.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@lists.osuosl.org
> 
> Signed-off-by: YiFei Zhu <zhuyifei@google.com>
> Signed-off-by: Mina Almasry <almasrymina@google.com>
> Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
> 
> ---
> 
> v3: https://lore.kernel.org/netdev/20251218022948.3288897-1-almasrymina@google.com/
> - Do the idpf_queue_has(PTP) check before we read qw1 (lobakin)
> - Fix _qw1 not copying over ts_low on on !__LIBETH_WORD_ACCESS systems
>   (AI)
> 
> 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 | 31 +++++++++++++++++++++++++++
>  drivers/net/ethernet/intel/idpf/xdp.h | 22 ++++++++++++++++++-
>  2 files changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/idpf/xdp.c b/drivers/net/ethernet/intel/idpf/xdp.c
> index 958d16f87424..0916d201bf98 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 +392,38 @@ 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;
> +
> +	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);
> +
> +	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,
>  };
>  
>  void idpf_xdp_set_features(const struct idpf_vport *vport)
> diff --git a/drivers/net/ethernet/intel/idpf/xdp.h b/drivers/net/ethernet/intel/idpf/xdp.h
> index 479f5ef3c604..9daae445bde4 100644
> --- a/drivers/net/ethernet/intel/idpf/xdp.h
> +++ b/drivers/net/ethernet/intel/idpf/xdp.h
> @@ -112,11 +112,13 @@ struct idpf_xdp_rx_desc {
>  	aligned_u64		qw1;
>  #define IDPF_XDP_RX_BUF		GENMASK_ULL(47, 32)
>  #define IDPF_XDP_RX_EOP		BIT_ULL(1)
> +#define IDPF_XDP_RX_TS_LOW	GENMASK_ULL(31, 24)
>  
>  	aligned_u64		qw2;
>  #define IDPF_XDP_RX_HASH	GENMASK_ULL(31, 0)
>  
>  	aligned_u64		qw3;
> +#define IDPF_XDP_RX_TS_HIGH	GENMASK_ULL(63, 32)
>  } __aligned(4 * sizeof(u64));
>  static_assert(sizeof(struct idpf_xdp_rx_desc) ==
>  	      sizeof(struct virtchnl2_rx_flex_desc_adv_nic_3));
> @@ -128,6 +130,8 @@ static_assert(sizeof(struct idpf_xdp_rx_desc) ==
>  #define idpf_xdp_rx_buf(desc)	FIELD_GET(IDPF_XDP_RX_BUF, (desc)->qw1)
>  #define idpf_xdp_rx_eop(desc)	!!((desc)->qw1 & IDPF_XDP_RX_EOP)
>  #define idpf_xdp_rx_hash(desc)	FIELD_GET(IDPF_XDP_RX_HASH, (desc)->qw2)
> +#define idpf_xdp_rx_ts_low(desc)	FIELD_GET(IDPF_XDP_RX_TS_LOW, (desc)->qw1)
> +#define idpf_xdp_rx_ts_high(desc)	FIELD_GET(IDPF_XDP_RX_TS_HIGH, (desc)->qw3)
>  
>  static inline void
>  idpf_xdp_get_qw0(struct idpf_xdp_rx_desc *desc,
> @@ -149,7 +153,10 @@ idpf_xdp_get_qw1(struct idpf_xdp_rx_desc *desc,
>  	desc->qw1 = ((const typeof(desc))rxd)->qw1;
>  #else
>  	desc->qw1 = ((u64)le16_to_cpu(rxd->buf_id) << 32) |
> -		    rxd->status_err0_qw1;
> +			((u64)rxd->ts_low << 24) |
> +			((u64)rxd->fflags1 << 16) |
> +			((u64)rxd->status_err1 << 8) |

I'm not sure you need casts to u64 here. Pls rebuild without them and
check the objdiff / compiler warnings.
It's required for buf_id as we shift by 32.

> +			rxd->status_err0_qw1;

Why did you replace the proper indentation with two tabs in all 4 lines
above?

Even though...

>  #endif
>  }
>  
> @@ -166,6 +173,19 @@ idpf_xdp_get_qw2(struct idpf_xdp_rx_desc *desc,
>  #endif
>  }
>  
> +static inline void
> +idpf_xdp_get_qw3(struct idpf_xdp_rx_desc *desc,
> +		 const struct virtchnl2_rx_flex_desc_adv_nic_3 *rxd)
> +{
> +#ifdef __LIBETH_WORD_ACCESS
> +	desc->qw3 = ((const typeof(desc))rxd)->qw3;
> +#else
> +	desc->qw3 = ((u64)le32_to_cpu(rxd->ts_high) << 32) |
> +		    ((u64)le16_to_cpu(rxd->fmd6) << 16) |
> +		    le16_to_cpu(rxd->l2tag1);

...here you use the correct one.

> +#endif
> +}
> +
>  void idpf_xdp_set_features(const struct idpf_vport *vport);
>  
>  int idpf_xdp(struct net_device *dev, struct netdev_bpf *xdp);
> 
> base-commit: 7b8e9264f55a9c320f398e337d215e68cca50131

Thanks,
Olek