[kvm-unit-tests PATCH] x86: pmu: Test WRMSR on a running counter

Eric Hankland
2020-02-04T01:25:12Z

Ensure that the value of the counter was successfully set to 0 after
writing it while the counter was running.

Signed-off-by: Eric Hankland <ehankland@google.com>
---
x86/pmu.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/x86/pmu.c b/x86/pmu.c
index cb8c9e3..8a77993 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -419,6 +419,21 @@ static void check_rdpmc(void)
report_prefix_pop();
}

+static void check_running_counter_wrmsr(void)
+{
+ pmu_counter_t evt = {
+ .ctr = MSR_IA32_PERFCTR0,
+ .config = EVNTSEL_OS | EVNTSEL_USR | gp_events[1].unit_sel,
+ .count = 0,
+ };
+
+ start_event(&evt);
+ loop();
+ wrmsr(MSR_IA32_PERFCTR0, 0);
+ stop_event(&evt);
+ report("running counter wrmsr", evt.count < gp_events[1].min);
+}
+
int main(int ac, char **av)
{
struct cpuid id = cpuid(10);
@@ -453,6 +468,7 @@ int main(int ac, char **av)
check_counters_many();
check_counter_overflow();
check_gp_counter_cmask();
+ check_running_counter_wrmsr();

return report_summary();
}