[PATCH 1/3] arm_pmu: Add support for perf NMI interrupts registration

[Lecopzer Chen]

Register perf interrupts by request_nmi()/percpu_nmi() when both
ARM64_PSEUDO_NMI and ARM64_PSEUDO_NMI_PERF are enabled and nmi
cpufreature is active.

Signed-off-by: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx>
---
 drivers/perf/arm_pmu.c       | 51 +++++++++++++++++++++++++++++++-----
 include/linux/perf/arm_pmu.h |  6 +++++
 2 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index df352b334ea7..fa37b72d19e2 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -559,6 +559,48 @@ void armpmu_free_irq(int irq, int cpu)
 	per_cpu(cpu_irq, cpu) = 0;
 }
 
+static void armpmu_prepare_percpu_nmi_other(void *info)
+{
+	/*
+	 * We don't need to disable preemption since smp_call_function()
+	 * did this for us.
+	 */
+	prepare_percpu_nmi((uintptr_t) info);
+}
+
+static int _armpmu_request_irq(unsigned int irq, irq_handler_t handler,
+			       unsigned long flags, int cpu)
+{
+	if (armpmu_support_nmi())
+		return request_nmi(irq, handler, flags, "arm-pmu",
+				   per_cpu_ptr(&cpu_armpmu, cpu));
+	return request_irq(irq, handler, flags, "arm-pmu",
+			   per_cpu_ptr(&cpu_armpmu, cpu));
+}
+
+static int _armpmu_request_percpu_irq(unsigned int irq, irq_handler_t handler)
+{
+	if (armpmu_support_nmi()) {
+		int err;
+
+		err = request_percpu_nmi(irq, handler, "arm-pmu",
+					 &cpu_armpmu);
+		if (err)
+			return err;
+
+		preempt_disable();
+		err = prepare_percpu_nmi(irq);
+		if (err) {
+			return err;
+			preempt_enable();
+		}
+		smp_call_function(armpmu_prepare_percpu_nmi_other,
+				  (void *)(uintptr_t) irq, true);
+		preempt_enable();
+	}
+	return request_percpu_irq(irq, handler, "arm-pmu",
+				  &cpu_armpmu);
+}
+
 int armpmu_request_irq(int irq, int cpu)
 {
 	int err = 0;
@@ -582,12 +624,9 @@ int armpmu_request_irq(int irq, int cpu)
 			    IRQF_NO_THREAD;
 
 		irq_set_status_flags(irq, IRQ_NOAUTOEN);
-		err = request_irq(irq, handler, irq_flags, "arm-pmu",
-				  per_cpu_ptr(&cpu_armpmu, cpu));
-	} else if (armpmu_count_irq_users(irq) == 0) {
-		err = request_percpu_irq(irq, handler, "arm-pmu",
-					 &cpu_armpmu);
-	}
+		err = _armpmu_request_irq(irq, handler, irq_flags, cpu);
+	} else if (armpmu_count_irq_users(irq) == 0)
+		err = _armpmu_request_percpu_irq(irq, handler);
 
 	if (err)
 		goto err_out;
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 5b616dde9a4c..5b878b5a22aa 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -160,6 +160,12 @@ int arm_pmu_acpi_probe(armpmu_init_fn init_fn);
 static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 0; }
 #endif
 
+static inline bool armpmu_support_nmi(void)
+{
+	return IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI_PERF) &&
+	       system_uses_irq_prio_masking();
+}
+
 /* Internal functions only for core arm_pmu code */
 struct arm_pmu *armpmu_alloc(void);
 struct arm_pmu *armpmu_alloc_atomic(void);
-- 
2.25.1