[PATCH v4 bpf-next 21/22] selftests/xsk: add test for too many frags

[Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>]

From: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>

Add a test for testing that a packet consisting of more than 18 frags
is discarded. This is only valid for SKB and DRV mode since in
zero-copy mode, this limit is up to the HW and what it supports.

Signed-off-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
---
 tools/testing/selftests/bpf/xskxceiver.c | 40 ++++++++++++++++++++++++
 tools/testing/selftests/bpf/xskxceiver.h |  2 ++
 2 files changed, 42 insertions(+)

diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c
index 848f48bb83e4..f5eed27759df 100644
--- a/tools/testing/selftests/bpf/xskxceiver.c
+++ b/tools/testing/selftests/bpf/xskxceiver.c
@@ -1982,6 +1982,43 @@ static int testapp_poll_rxq_tmout(struct test_spec *test)
 	return testapp_validate_traffic_single_thread(test, test->ifobj_rx);
 }
 
+static int testapp_too_many_frags(struct test_spec *test)
+{
+	struct pkt pkts[2 * XSK_DESC__MAX_FRAGS + 2] = {};
+	u32 i;
+
+	test_spec_set_name(test, "TOO_MANY_FRAGS");
+	if (test->mode == TEST_MODE_ZC) {
+		/* Limit is up to driver for zero-copy mode so not testable. */
+		ksft_test_result_skip("Cannot be run for zero-copy mode.\n");
+		return TEST_SKIP;
+	}
+
+	test->mtu = MAX_ETH_JUMBO_SIZE;
+
+	/* Valid packet for synch */
+	pkts[0].len = MIN_PKT_SIZE;
+	pkts[0].valid = true;
+
+	/* Produce two longs packets below out of this */
+	for (i = 1; i < 2 * XSK_DESC__MAX_FRAGS + 1; i++) {
+		pkts[i].len = MIN_PKT_SIZE;
+		pkts[i].options = XDP_PKT_CONTD;
+		pkts[i].valid = true;
+	}
+	/* 1st packet: Produce the highest amount of frags possible */
+	pkts[XSK_DESC__MAX_FRAGS].options = 0;
+	/* 2nd packet: Do not signal end-of-packet in the 17th frag. This is not legal. */
+	pkts[2 * XSK_DESC__MAX_FRAGS].valid = false;
+
+	/* Valid packet for synch */
+	pkts[2 * XSK_DESC__MAX_FRAGS + 1].len = MIN_PKT_SIZE;
+	pkts[2 * XSK_DESC__MAX_FRAGS + 1].valid = true;
+
+	pkt_stream_generate_custom(test, pkts, ARRAY_SIZE(pkts));
+	return testapp_validate_traffic(test);
+}
+
 static int xsk_load_xdp_programs(struct ifobject *ifobj)
 {
 	ifobj->xdp_progs = xsk_xdp_progs__open_and_load();
@@ -2169,6 +2206,9 @@ static void run_pkt_test(struct test_spec *test, enum test_mode mode, enum test_
 		test->mtu = MAX_ETH_JUMBO_SIZE;
 		ret = testapp_xdp_metadata_count(test);
 		break;
+	case TEST_TYPE_TOO_MANY_FRAGS:
+		ret = testapp_too_many_frags(test);
+		break;
 	default:
 		break;
 	}
diff --git a/tools/testing/selftests/bpf/xskxceiver.h b/tools/testing/selftests/bpf/xskxceiver.h
index 9e1f66e0a3b6..0621b6fb8fb3 100644
--- a/tools/testing/selftests/bpf/xskxceiver.h
+++ b/tools/testing/selftests/bpf/xskxceiver.h
@@ -53,6 +53,7 @@
 #define XSK_UMEM__LARGE_FRAME_SIZE (3 * 1024)
 #define XSK_UMEM__MAX_FRAME_SIZE (4 * 1024)
 #define XSK_DESC__INVALID_OPTION (0xffff)
+#define XSK_DESC__MAX_FRAGS 18
 #define HUGEPAGE_SIZE (2 * 1024 * 1024)
 #define PKT_DUMP_NB_TO_PRINT 16
 
@@ -93,6 +94,7 @@ enum test_type {
 	TEST_TYPE_UNALIGNED_MB,
 	TEST_TYPE_ALIGNED_INV_DESC_MB,
 	TEST_TYPE_UNALIGNED_INV_DESC_MB,
+	TEST_TYPE_TOO_MANY_FRAGS,
 	TEST_TYPE_MAX
 };
 
-- 
2.34.1