[tip: perf/core] perf/x86/cstate: Allow reading the package statistics from local CPU

[tip-bot2 for Tero Kristo]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     05276d4831fe023b6674a72bd6b8c5b39796e690
Gitweb:        https://git.kernel.org/tip/05276d4831fe023b6674a72bd6b8c5b39796e690
Author:        Tero Kristo <tero.kristo@xxxxxxxxxxxxxxx>
AuthorDate:    Tue, 12 Sep 2023 15:44:31 +03:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 09 Oct 2023 16:12:22 +02:00

perf/x86/cstate: Allow reading the package statistics from local CPU

The MSR registers for reading the package residency counters are
available on every CPU of the package. To avoid doing unnecessary SMP
calls to read the values for these from the various CPUs inside a
package, allow reading them from any CPU of the package.

Suggested-by: Kan Liang <kan.liang@xxxxxxxxx>
Signed-off-by: Tero Kristo <tero.kristo@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20230912124432.3616761-2-tero.kristo@xxxxxxxxxxxxxxx
---
 arch/x86/events/intel/cstate.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/events/intel/cstate.c b/arch/x86/events/intel/cstate.c
index 96fffb2..cbeb6d2 100644
--- a/arch/x86/events/intel/cstate.c
+++ b/arch/x86/events/intel/cstate.c
@@ -336,6 +336,9 @@ static int cstate_pmu_event_init(struct perf_event *event)
 		cfg = array_index_nospec((unsigned long)cfg, PERF_CSTATE_PKG_EVENT_MAX);
 		if (!(pkg_msr_mask & (1 << cfg)))
 			return -EINVAL;
+
+		event->event_caps |= PERF_EV_CAP_READ_ACTIVE_PKG;
+
 		event->hw.event_base = pkg_msr[cfg].msr;
 		cpu = cpumask_any_and(&cstate_pkg_cpu_mask,
 				      topology_die_cpumask(event->cpu));