[Intel-wired-lan] [PATCH] igc: Fix HW RX timestamp when passed by ZC XDP

[Mor Bar-Gabay]

On 28/01/2025 14:26, Zdenek Bouska wrote:
> Fixes HW RX timestamp in the following scenario:
> - AF_PACKET socket with enabled HW RX timestamps is created
> - AF_XDP socket with enabled zero copy is created
> - frame is forwarded to the BPF program, where the timestamp should
>    still be readable (extracted by igc_xdp_rx_timestamp(), kfunc
>    behind bpf_xdp_metadata_rx_timestamp())
> - the frame got XDP_PASS from BPF program, redirecting to the stack
> - AF_PACKET socket receives the frame with HW RX timestamp
> 
> Moves the skb timestamp setting from igc_dispatch_skb_zc() to
> igc_construct_skb_zc() so that igc_construct_skb_zc() is similar to
> igc_construct_skb().
> 
> This issue can also be reproduced by running:
>   # tools/testing/selftests/bpf/xdp_hw_metadata enp1s0
> When a frame with the wrong port 9092 (instead of 9091) is used:
>   # echo -n xdp | nc -u -q1 192.168.10.9 9092
> then the RX timestamp is missing and xdp_hw_metadata prints:
>   skb hwtstamp is not found!
> 
> With this fix or when copy mode is used:
>   # tools/testing/selftests/bpf/xdp_hw_metadata -c enp1s0
> then RX timestamp is found and xdp_hw_metadata prints:
>   found skb hwtstamp = 1736509937.852786132
> 
> Fixes: 069b142f5819 ("igc: Add support for PTP .getcyclesx64()")
> Signed-off-by: Zdenek Bouska <zdenek.bouska at siemens.com>
> Acked-by: Vinicius Costa Gomes <vinicius.gomes at intel.com>
> Reviewed-by: Simon Horman <horms at kernel.org>
> Reviewed-by: Florian Bezdeka <florian.bezdeka at siemens.com>
> Reviewed-by: Song Yoong Siang <yoong.siang.song at intel.com>
> ---
>   drivers/net/ethernet/intel/igc/igc_main.c | 21 ++++++++++++---------
>   1 file changed, 12 insertions(+), 9 deletions(-)
> 
Tested-by: Mor Bar-Gabay <morx.bar.gabay at intel.com>