Commit aa67fdb4 authored by Song Liu's avatar Song Liu Committed by Andrii Nakryiko
Browse files

selftests/bpf: Skip the second half of get_branch_snapshot in vm 



VMs running on upstream 5.12+ kernel support LBR. However,
bpf_get_branch_snapshot couldn't stop the LBR before too many entries
are flushed. Skip the hit/waste test for VMs before we find a proper fix
for LBR in VM.

Fixes: 025bd7c7 ("selftests/bpf: Add test for bpf_get_branch_snapshot")
Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211007050231.728496-1-songliubraving@fb.com
parent 0eb4ef88

tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c

+34 −0
Original line number Diff line number Diff line
@@ -6,6 +6,30 @@ 
static int *pfd_array;

static int cpu_cnt;



static bool is_hypervisor(void)

{

	char *line = NULL;

	bool ret = false;

	size_t len;

	FILE *fp;



	fp = fopen("/proc/cpuinfo", "r");

	if (!fp)

		return false;



	while (getline(&line, &len, fp) != -1) {

		if (!strncmp(line, "flags", 5)) {

			if (strstr(line, "hypervisor") != NULL)

				ret = true;

			break;

		}

	}



	free(line);

	fclose(fp);

	return ret;

}



static int create_perf_events(void)

{

	struct perf_event_attr attr = {0};
@@ -83,6 +107,16 @@ void test_get_branch_snapshot(void) 
		goto cleanup;

	}



	if (is_hypervisor()) {

		/* As of today, LBR in hypervisor cannot be stopped before

		 * too many entries are flushed. Skip the hit/waste test

		 * for now in hypervisor until we optimize the LBR in

		 * hypervisor.

		 */

		test__skip();

		goto cleanup;

	}



	ASSERT_GT(skel->bss->test1_hits, 6, "find_looptest_in_lbr");



	/* Given we stop LBR in software, we will waste a few entries.