perf/x86: Track pmu in per-CPU cpu_hw_events

Some platforms, e.g. Alder Lake, have hybrid architecture. In the same
package, there may be more than one type of CPU. The PMU capabilities
are different among different types of CPU. Perf will register a
dedicated PMU for each type of CPU.

Add a 'pmu' variable in the struct cpu_hw_events to track the dedicated
PMU of the current CPU.

Current x86_get_pmu() use the global 'pmu', which will be broken on a
hybrid platform. Modify it to apply the 'pmu' of the specific CPU.

Initialize the per-CPU 'pmu' variable with the global 'pmu'. There is
nothing changed for the non-hybrid platforms.

The is_x86_event() will be updated in the later patch ("perf/x86:
Register hybrid PMUs") for hybrid platforms. For the non-hybrid
platforms, nothing is changed here.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1618237865-33448-4-git-send-email-kan.liang@linux.intel.com

1 files changed, 13 insertions, 4 deletions

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index dd9f3c2f7d05..a49a8bd6267c 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -45,9 +45,11 @@
 #include "perf_event.h"
 
 struct x86_pmu x86_pmu __read_mostly;
+static struct pmu pmu;
 
 DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
 	.enabled = 1,
+	.pmu = &pmu,
 };
 
 DEFINE_STATIC_KEY_FALSE(rdpmc_never_available_key);
@@ -724,16 +726,23 @@ void x86_pmu_enable_all(int added)
 	}
 }
 
-static struct pmu pmu;
-
 static inline int is_x86_event(struct perf_event *event)
 {
 	return event->pmu == &pmu;
 }
 
-struct pmu *x86_get_pmu(void)
+struct pmu *x86_get_pmu(unsigned int cpu)
 {
-	return &pmu;
+	struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
+
+	/*
+	 * All CPUs of the hybrid type have been offline.
+	 * The x86_get_pmu() should not be invoked.
+	 */
+	if (WARN_ON_ONCE(!cpuc->pmu))
+		return &pmu;
+
+	return cpuc->pmu;
 }
 /*
  * Event scheduler state: