[PATCH bpf-next V2 4/5] igc: add XDP hints kfuncs for RX timestamp

Jesper Dangaard Brouer
2023-04-18T13:32:10Z

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>
---
drivers/net/ethernet/intel/igc/igc.h | 1 +
drivers/net/ethernet/intel/igc/igc_main.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index c609a2e648f8..18d4af934d8c 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 9cb43c0eab73..38d113b48111 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -2552,6 +2552,7 @@ 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;
}
@@ -2740,6 +2741,7 @@ 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;

@@ -6526,8 +6528,22 @@ static int igc_xdp_rx_hash(const struct xdp_md *_ctx, u32 *hash,
return 0;
}

+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;
+}
+
static const struct xdp_metadata_ops igc_xdp_metadata_ops = {
.xmo_rx_hash = igc_xdp_rx_hash,
+ .xmo_rx_timestamp = igc_xdp_rx_timestamp,
};

/**