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

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Date:   Wed, 12 Apr 2023 11:40:43 +0000
From:   "Song, Yoong Siang" <yoong.siang.song@...el.com>
To:     "Brouer, Jesper" <brouer@...hat.com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>
CC:     "Brouer, Jesper" <brouer@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        "martin.lau@...nel.org" <martin.lau@...nel.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "Lobakin, Aleksander" <aleksander.lobakin@...el.com>,
        "Zaremba, Larysa" <larysa.zaremba@...el.com>,
        "xdp-hints@...-project.net" <xdp-hints@...-project.net>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "Ong, Boon Leong" <boon.leong.ong@...el.com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "john.fastabend@...il.com" <john.fastabend@...il.com>,
        "hawk@...nel.org" <hawk@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: RE: [PATCH bpf-next V3 5/6] igc: add XDP hints kfuncs for RX
 timestamp

On Thursday, March 23, 2023 12:02 AM , Jesper Dangaard Brouer <brouer@...hat.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@...hat.com>
>---
> 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;
>
>