[xdp-hints] [PATCH bpf-next v2 3/3] selftests/bpf: Add txtime to xdp_hw_metadata

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

This patch adds txtime support to xdp_hw_metadata. User can configure the
delta of HW txtime to HW RX-time by using "-l" argument. The default delta
is set to 1 second.

This patch is tested with stmmac on Intel Tiger Lake platform. Refer to
result below, the delta between pre-determined ETF txtime and actual HW
transmit complete time is around 24 us.

$ sudo ./xdp_hw_metadata eth0
...
xsk_ring_cons__peek: 1
0x55fcb80ce7a8: rx_desc[0]->addr=80100 addr=80100 comp_addr=80100 EoP
No rx_hash err=-95
HW RX-time:   1677764507059055964 (sec:1677764507.0591) delta to User RX-time sec:0.0002 (237.548 usec)
XDP RX-time:   1677764507059280741 (sec:1677764507.0593) delta to User RX-time sec:0.0000 (12.771 usec)
0x55fcb80ce7a8: ping-pong with csum=5619 (want 8626) csum_start=34 csum_offset=6
HW RX-time:   1677764507059055964 (sec:1677764507.0591) delta to HW Txtime sec:1.0000 (1000000.000 usec)
0x55fcb80ce7a8: complete tx idx=0 addr=18
HW Txtime:   1677764508059055964 (sec:1677764508.0591) delta to HW TX-complete-time sec:0.0000 (24.235 usec)
HW TX-complete-time:   1677764508059080199 (sec:1677764508.0591) delta to User TX-complete-time sec:0.0054 (5423.263 usec)
XDP RX-time:   1677764507059280741 (sec:1677764507.0593) delta to User TX-complete-time sec:1.0052 (1005222.721 usec)
HW RX-time:   1677764507059055964 (sec:1677764507.0591) delta to HW TX-complete-time sec:1.0000 (1000024.235 usec)
0x55fcb80ce7a8: complete rx idx=128 addr=80100

$ sudo ./xdp_hw_metadata eth0 -l 10000000
...
xsk_ring_cons__peek: 1
0x5626d54de7a8: rx_desc[0]->addr=80100 addr=80100 comp_addr=80100 EoP
No rx_hash err=-95
HW RX-time:   1677764655807717783 (sec:1677764655.8077) delta to User RX-time sec:0.0002 (240.571 usec)
XDP RX-time:   1677764655807942983 (sec:1677764655.8079) delta to User RX-time sec:0.0000 (15.371 usec)
0x5626d54de7a8: ping-pong with csum=5619 (want 8626) csum_start=34 csum_offset=6
HW RX-time:   1677764655807717783 (sec:1677764655.8077) delta to HW Txtime sec:0.0100 (10000.000 usec)
0x5626d54de7a8: complete tx idx=0 addr=18
HW Txtime:   1677764655817717783 (sec:1677764655.8177) delta to HW TX-complete-time sec:0.0000 (23.965 usec)
HW TX-complete-time:   1677764655817741748 (sec:1677764655.8177) delta to User TX-complete-time sec:0.0003 (291.792 usec)
XDP RX-time:   1677764655807942983 (sec:1677764655.8079) delta to User TX-complete-time sec:0.0101 (10090.557 usec)
HW RX-time:   1677764655807717783 (sec:1677764655.8077) delta to HW TX-complete-time sec:0.0100 (10023.965 usec)
0x5626d54de7a8: complete rx idx=128 addr=80100

Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
---
 tools/testing/selftests/bpf/xdp_hw_metadata.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
index 3291625ba4fb..e9c3e29dc538 100644
--- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
+++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
@@ -13,6 +13,7 @@
  * - UDP 9091 packets trigger TX reply
  * - TX HW timestamp is requested and reported back upon completion
  * - TX checksum is requested
+ * - HW txtime is set for transmission
  */
 
 #include <test_progs.h>
@@ -61,6 +62,8 @@ int rxq;
 bool skip_tx;
 __u64 last_hw_rx_timestamp;
 __u64 last_xdp_rx_timestamp;
+__u64 last_txtime;
+__u64 txtime_delta_to_hw_rx_timestamp = 1000000000; /* 1 second */
 
 void test__fail(void) { /* for network_helpers.c */ }
 
@@ -274,6 +277,8 @@ static bool complete_tx(struct xsk *xsk, clockid_t clock_id)
 	if (meta->completion.tx_timestamp) {
 		__u64 ref_tstamp = gettime(clock_id);
 
+		print_tstamp_delta("HW Txtime", "HW TX-complete-time",
+				   last_txtime, meta->completion.tx_timestamp);
 		print_tstamp_delta("HW TX-complete-time", "User TX-complete-time",
 				   meta->completion.tx_timestamp, ref_tstamp);
 		print_tstamp_delta("XDP RX-time", "User TX-complete-time",
@@ -371,6 +376,13 @@ static void ping_pong(struct xsk *xsk, void *rx_packet, clockid_t clock_id)
 	       xsk, ntohs(udph->check), ntohs(want_csum),
 	       meta->request.csum_start, meta->request.csum_offset);
 
+	/* Set txtime for Earliest TxTime First (ETF) */
+	meta->flags |= XDP_TXMD_FLAGS_TXTIME;
+	meta->request.txtime = last_hw_rx_timestamp + txtime_delta_to_hw_rx_timestamp;
+	last_txtime = meta->request.txtime;
+	print_tstamp_delta("HW RX-time", "HW Txtime", last_hw_rx_timestamp,
+			   meta->request.txtime);
+
 	memcpy(data, rx_packet, len); /* don't share umem chunk for simplicity */
 	tx_desc->options |= XDP_TX_METADATA;
 	tx_desc->len = len;
@@ -595,6 +607,7 @@ static void print_usage(void)
 		"  -h    Display this help and exit\n\n"
 		"  -m    Enable multi-buffer XDP for larger MTU\n"
 		"  -r    Don't generate AF_XDP reply (rx metadata only)\n"
+		"  -l    Delta of HW Txtime to HW RX-time in ns (default: 1s)\n"
 		"Generate test packets on the other machine with:\n"
 		"  echo -n xdp | nc -u -q1 <dst_ip> 9091\n";
 
@@ -605,7 +618,7 @@ static void read_args(int argc, char *argv[])
 {
 	int opt;
 
-	while ((opt = getopt(argc, argv, "chmr")) != -1) {
+	while ((opt = getopt(argc, argv, "chmrl:")) != -1) {
 		switch (opt) {
 		case 'c':
 			bind_flags &= ~XDP_USE_NEED_WAKEUP;
@@ -621,6 +634,9 @@ static void read_args(int argc, char *argv[])
 		case 'r':
 			skip_tx = true;
 			break;
+		case 'l':
+			txtime_delta_to_hw_rx_timestamp = atoll(optarg);
+			break;
 		case '?':
 			if (isprint(optopt))
 				fprintf(stderr, "Unknown option: -%c\n", optopt);
-- 
2.34.1