On Wed, Oct 6, 2021 at 2:36 PM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Wed, Oct 6, 2021 at 1:31 PM Song Liu <songliubraving@xxxxxx> wrote:
> >
> > VMs running on latest kernel support LBR. However, bpf_get_branch_snapshot
> > couldn't stop the LBR before too many entries are flushed. Skip the test
> > for VMs before we find a proper fix for VMs.
> >
> > Read the "flags" line from /proc/cpuinfo, if it contains "hypervisor",
> > skip test get_branch_snapshot.
> >
> > Fixes: 025bd7c753aa (selftests/bpf: Add test for bpf_get_branch_snapshot)
>
> missing quotes?
Aha, I copied this line from e31eec77e4ab90dcec7d2da93415f839098dc287. Will fix.
>
> > Signed-off-by: Song Liu <songliubraving@xxxxxx>
> > ---
> > .../bpf/prog_tests/get_branch_snapshot.c | 32 +++++++++++++++++++
> > 1 file changed, 32 insertions(+)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c
> > index 67e86f8d86775..bf9d47a859449 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/get_branch_snapshot.c
> > @@ -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 (strstr(line, "flags") == line) {
>
> strncmp() would be more explicit. That's what you are trying to do
> (prefix match), right?
right... let me fix it in v2.
>
> > + 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};
> > @@ -54,6 +78,14 @@ void test_get_branch_snapshot(void)
> > struct get_branch_snapshot *skel = NULL;
> > int err;
> >
> > + if (is_hypervisor()) {
> > + /* As of today, LBR in hypervisor cannot be stopped before
> > + * too many entries are flushed. Skip the test for now in
> > + * hypervisor until we optimize the LBR in hypervisor.
> > + */
> > + test__skip();
> > + return;
> > + }
> > if (create_perf_events()) {
> > test__skip(); /* system doesn't support LBR */
> > goto cleanup;
> > --
> > 2.30.2
> >
