[xdp-hints] Re: [PATCH bpf-next V3 5/6] igc: add XDP hints kfuncs for RX timestamp

["Song, Yoong Siang" <yoong.siang.song@intel.com>]

On Wednesday, April 12, 2023 7:41 PM, Song Yoong Siang wrote:
>On Thursday, March 23, 2023 12:02 AM , Jesper Dangaard Brouer
><brouer@redhat.com> wrote:
>>The NIC hardware RX timestamping mechanism adds an optional tailored
>>header before the MAC header containing packet reception time. Optional
>>depending on RX descriptor TSIP status bit (IGC_RXDADV_STAT_TSIP). In
>>case this bit is set driver does offset adjustments to packet data start and
>extracts the timestamp.
>>
>>The timestamp need to be extracted before invoking the XDP bpf_prog,
>>because this area just before the packet is also accessible by XDP via
>>data_meta context pointer (and helper bpf_xdp_adjust_meta). Thus, an
>>XDP bpf_prog can potentially overwrite this and corrupt data that we
>>want to extract with the new kfunc for reading the timestamp.
>>
>>Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>

Tested-by: Song Yoong Siang <yoong.siang.song@intel.com>

Tested Rx HWTS metadata on I226-LM (rev 04) NIC.
Below are the detail of test steps and result.

1. Run xdp_hw_metadata tool.
   @DUT: sudo ./xdp_hw_metadata eth0

2. Enable Rx HWTS for all incoming packets. Note: This step should not needed, so
   it should be a HWTS enablement bug on igc driver. I will take a look on it.
   @DUT: sudo hwstamp_ctl -i eth0 -r 1

3. Set the ptp clock time from the system time using testptp tool.
   @DUT: sudo ./testptp -d /dev/ptp0 -s

4. Send UDP packet with 9091 port from link partner immediately after step 3.
   @LinkPartner: echo -n xdp | nc -u -q1 <Destination IPv4 addr> 9091

Result:
   xsk_ring_cons__peek: 1
   0x559288636880: rx_desc[2]->addr=100000000202000 addr=202100 comp_addr=202000
   rx_hash: 0x0E550050
   rx_timestamp:  1677762906850259640 (sec:1677762906.8503)
   XDP RX-time:   1677762906850374981 (sec:1677762906.8504) delta sec:0.0001 (115.341 usec)
   AF_XDP time:   1677762906850396571 (sec:1677762906.8504) delta sec:0.0000 (21.590 usec)
   0x559288636880: complete idx=514 addr=202000

>>---
>> drivers/net/ethernet/intel/igc/igc.h      |    1 +
>> drivers/net/ethernet/intel/igc/igc_main.c |   20 ++++++++++++++++++++
>> 2 files changed, 21 insertions(+)
>>
>>diff --git a/drivers/net/ethernet/intel/igc/igc.h
>>b/drivers/net/ethernet/intel/igc/igc.h
>>index bc67a52e47e8..29941734f1a1 100644
>>--- a/drivers/net/ethernet/intel/igc/igc.h
>>+++ b/drivers/net/ethernet/intel/igc/igc.h
>>@@ -503,6 +503,7 @@ struct igc_rx_buffer {  struct igc_xdp_buff {
>> 	struct xdp_buff xdp;
>> 	union igc_adv_rx_desc *rx_desc;
>>+	ktime_t rx_ts; /* data indication bit IGC_RXDADV_STAT_TSIP */
>> };
>>
>> struct igc_q_vector {
>>diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
>>b/drivers/net/ethernet/intel/igc/igc_main.c
>>index a78d7e6bcfd6..f66285c85444 100644
>>--- a/drivers/net/ethernet/intel/igc/igc_main.c
>>+++ b/drivers/net/ethernet/intel/igc/igc_main.c
>>@@ -2539,6 +2539,7 @@ static int igc_clean_rx_irq(struct igc_q_vector
>>*q_vector, const int budget)
>> 		if (igc_test_staterr(rx_desc, IGC_RXDADV_STAT_TSIP)) {
>> 			timestamp = igc_ptp_rx_pktstamp(q_vector->adapter,
>> 							pktbuf);
>>+			ctx.rx_ts = timestamp;
>> 			pkt_offset = IGC_TS_HDR_LEN;
>> 			size -= IGC_TS_HDR_LEN;
>> 		}
>>@@ -2727,6 +2728,7 @@ static int igc_clean_rx_irq_zc(struct
>>igc_q_vector *q_vector, const int budget)
>> 		if (igc_test_staterr(desc, IGC_RXDADV_STAT_TSIP)) {
>> 			timestamp = igc_ptp_rx_pktstamp(q_vector->adapter,
>> 							bi->xdp->data);
>>+			ctx->rx_ts = timestamp;
>>
>> 			bi->xdp->data += IGC_TS_HDR_LEN;
>>
>>@@ -6481,6 +6483,23 @@ u32 igc_rd32(struct igc_hw *hw, u32 reg)
>> 	return value;
>> }
>>
>>+static int igc_xdp_rx_timestamp(const struct xdp_md *_ctx, u64
>>+*timestamp) {
>>+	const struct igc_xdp_buff *ctx = (void *)_ctx;
>>+
>>+	if (igc_test_staterr(ctx->rx_desc, IGC_RXDADV_STAT_TSIP)) {
>>+		*timestamp = ctx->rx_ts;
>>+
>>+		return 0;
>>+	}
>>+
>>+	return -ENODATA;
>>+}
>>+
>>+const struct xdp_metadata_ops igc_xdp_metadata_ops = {
>
>Hi Jesper,
>
>Since igc_xdp_metadata_ops is used on igc_main.c only, we can make it static to
>avoid following build warning:
>
>drivers/net/ethernet/intel/igc/igc_main.c:6499:31: warning: symbol
>'igc_xdp_metadata_ops' was not declared. Should it be static?
>
>Thanks & Regards
>Siang
>
>>+	.xmo_rx_timestamp		= igc_xdp_rx_timestamp,
>>+};
>>+
>> /**
>>  * igc_probe - Device Initialization Routine
>>  * @pdev: PCI device information struct @@ -6554,6 +6573,7 @@ static
>>int igc_probe(struct pci_dev *pdev,
>> 	hw->hw_addr = adapter->io_addr;
>>
>> 	netdev->netdev_ops = &igc_netdev_ops;
>>+	netdev->xdp_metadata_ops = &igc_xdp_metadata_ops;
>> 	igc_ethtool_set_ops(netdev);
>> 	netdev->watchdog_timeo = 5 * HZ;
>>
>>