[PATCH AUTOSEL 5.16 15/52] perf/x86/rapl: fix AMD event handling

Sasha Levin
2022-02-03T20:30:59Z

From: Stephane Eranian <eranian@google.com>

[ Upstream commit 0036fb00a756a2f6e360d44e2e3d2200a8afbc9b ]

The RAPL events exposed under /sys/devices/power/events should only reflect
what the underlying hardware actually support. This is how it works on Intel
RAPL and Intel core/uncore PMUs in general.
But on AMD, this was not the case. All possible RAPL events were advertised.

This is what it showed on an AMD Fam17h:
$ ls /sys/devices/power/events/
energy-cores energy-gpu energy-pkg energy-psys
energy-ram energy-cores.scale energy-gpu.scale energy-pkg.scale
energy-psys.scale energy-ram.scale energy-cores.unit energy-gpu.unit
energy-pkg.unit energy-psys.unit energy-ram.unit

Yet, on AMD Fam17h, only energy-pkg is supported.

This patch fixes the problem. Given the way perf_msr_probe() works, the
amd_rapl_msrs[] table has to have all entries filled out and in particular
the group field, otherwise perf_msr_probe() defaults to making the event
visible.

With the patch applied, the kernel now only shows was is actually supported:

$ ls /sys/devices/power/events/
energy-pkg energy-pkg.scale energy-pkg.unit

The patch also uses the RAPL_MSR_MASK because only the 32-bits LSB of the
RAPL counters are relevant when reading power consumption.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220105185659.643355-1-eranian@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/events/rapl.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
index 85feafacc445d..77e3a47af5ad5 100644
--- a/arch/x86/events/rapl.c
+++ b/arch/x86/events/rapl.c
@@ -536,11 +536,14 @@ static struct perf_msr intel_rapl_spr_msrs[] = {
* - perf_msr_probe(PERF_RAPL_MAX)
* - want to use same event codes across both architectures
*/
-static struct perf_msr amd_rapl_msrs[PERF_RAPL_MAX] = {
- [PERF_RAPL_PKG] = { MSR_AMD_PKG_ENERGY_STATUS, &rapl_events_pkg_group, test_msr },
+static struct perf_msr amd_rapl_msrs[] = {
+ [PERF_RAPL_PP0] = { 0, &rapl_events_cores_group, 0, false, 0 },
+ [PERF_RAPL_PKG] = { MSR_AMD_PKG_ENERGY_STATUS, &rapl_events_pkg_group, test_msr, false, RAPL_MSR_MASK },
+ [PERF_RAPL_RAM] = { 0, &rapl_events_ram_group, 0, false, 0 },
+ [PERF_RAPL_PP1] = { 0, &rapl_events_gpu_group, 0, false, 0 },
+ [PERF_RAPL_PSYS] = { 0, &rapl_events_psys_group, 0, false, 0 },
};

-
static int rapl_cpu_offline(unsigned int cpu)
{
struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
--
2.34.1