[PATCH RFC bpf-next 16/52] selftests/bpf: expand xdp_link to check that setting meta opts works

[Alexander Lobakin]

Add a check in xdp_link to ensure that the values of btf_id and
meta_thresh gotten via bpf_obj_get_info_by_fd() is the same as was
passed via bpf_link_update(). Plus, that the kernel should fail to
set btf_id to 0 when meta_thresh != 0.
Also, use the new bpf_program__attach_xdp_opts() instead of the
non-optsed version and set the initial metadata threshold value
to check whether the kernel is able to process this request.
When the threshold is being set via the Netlink interface, it's
not being stored anywhere in the kernel core, so no test for it.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
---
 .../selftests/bpf/prog_tests/xdp_link.c       | 30 +++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_link.c b/tools/testing/selftests/bpf/prog_tests/xdp_link.c
index 3e9d5c5521f0..0723278c448f 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_link.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_link.c
@@ -10,6 +10,7 @@ void serial_test_xdp_link(void)
 {
 	struct test_xdp_link *skel1 = NULL, *skel2 = NULL;
 	__u32 id1, id2, id0 = 0, prog_fd1, prog_fd2;
+	LIBBPF_OPTS(bpf_link_update_opts, lu_opts);
 	LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
 	struct bpf_link_info link_info;
 	struct bpf_prog_info prog_info;
@@ -103,8 +104,16 @@ void serial_test_xdp_link(void)
 	bpf_link__destroy(skel1->links.xdp_handler);
 	skel1->links.xdp_handler = NULL;
 
+	opts.old_prog_fd = 0;
+	opts.meta_thresh = 128;
+
+	err = libbpf_get_type_btf_id("struct xdp_meta_generic", &opts.btf_id);
+	if (!ASSERT_OK(err, "libbpf_get_type_btf_id"))
+		goto cleanup;
+
 	/* new link attach should succeed */
-	link = bpf_program__attach_xdp(skel2->progs.xdp_handler, IFINDEX_LO);
+	link = bpf_program__attach_xdp_opts(skel2->progs.xdp_handler,
+					    IFINDEX_LO, &opts);
 	if (!ASSERT_OK_PTR(link, "link_attach"))
 		goto cleanup;
 	skel2->links.xdp_handler = link;
@@ -113,11 +122,25 @@ void serial_test_xdp_link(void)
 	if (!ASSERT_OK(err, "id2_check_err") || !ASSERT_EQ(id0, id2, "id2_check_val"))
 		goto cleanup;
 
+	lu_opts.xdp.new_meta_thresh = 256;
+	lu_opts.xdp.new_btf_id = opts.btf_id;
+
 	/* updating program under active BPF link works as expected */
-	err = bpf_link__update_program(link, skel1->progs.xdp_handler);
+	err = bpf_link_update(bpf_link__fd(link),
+			      bpf_program__fd(skel1->progs.xdp_handler),
+			      &lu_opts);
 	if (!ASSERT_OK(err, "link_upd"))
 		goto cleanup;
 
+	lu_opts.xdp.new_btf_id = 0;
+
+	/* BTF ID can't be 0 when meta_thresh != 0, and vice versa */
+	err = bpf_link_update(bpf_link__fd(link),
+			      bpf_program__fd(skel1->progs.xdp_handler),
+			      &lu_opts);
+	if (!ASSERT_ERR(err, "link_upd_fail"))
+		goto cleanup;
+
 	memset(&link_info, 0, sizeof(link_info));
 	err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &link_info, &link_info_len);
 	if (!ASSERT_OK(err, "link_info"))
@@ -126,6 +149,9 @@ void serial_test_xdp_link(void)
 	ASSERT_EQ(link_info.type, BPF_LINK_TYPE_XDP, "link_type");
 	ASSERT_EQ(link_info.prog_id, id1, "link_prog_id");
 	ASSERT_EQ(link_info.xdp.ifindex, IFINDEX_LO, "link_ifindex");
+	ASSERT_EQ(link_info.xdp.btf_id, opts.btf_id, "btf_id");
+	ASSERT_EQ(link_info.xdp.meta_thresh, lu_opts.xdp.new_meta_thresh,
+		  "meta_thresh");
 
 	/* updating program under active BPF link with different type fails */
 	err = bpf_link__update_program(link, skel1->progs.tc_handler);
-- 
2.36.1