1 files changed, 49 insertions, 46 deletions

diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
index 99abea3b2cc9..a085e45b509e 100644
--- a/drivers/perf/arm_pmu_acpi.c
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -13,6 +13,7 @@
 #include <linux/percpu.h>
 #include <linux/perf/arm_pmu.h>
 
+#include <asm/cpu.h>
 #include <asm/cputype.h>
 
 static DEFINE_PER_CPU(struct arm_pmu *, probed_pmus);
@@ -204,26 +205,6 @@ static struct arm_pmu *arm_pmu_acpi_find_pmu(void)
 	return NULL;
 }
 
-static struct arm_pmu *arm_pmu_acpi_find_alloc_pmu(void)
-{
-	struct arm_pmu *pmu;
-
-	pmu = arm_pmu_acpi_find_pmu();
-	if (pmu)
-		return pmu;
-
-	pmu = armpmu_alloc_atomic();
-	if (!pmu) {
-		pr_warn("Unable to allocate PMU for CPU%d\n",
-			smp_processor_id());
-		return NULL;
-	}
-
-	pmu->acpi_cpuid = read_cpuid_id();
-
-	return pmu;
-}
-
 /*
  * Check whether the new IRQ is compatible with those already associated with
  * the PMU (e.g. we don't have mismatched PPIs).
@@ -286,26 +267,45 @@ static int arm_pmu_acpi_cpu_starting(unsigned int cpu)
 	if (per_cpu(probed_pmus, cpu))
 		return 0;
 
-	pmu = arm_pmu_acpi_find_alloc_pmu();
-	if (!pmu)
-		return -ENOMEM;
+	pmu = arm_pmu_acpi_find_pmu();
+	if (!pmu) {
+		pr_warn_ratelimited("Unable to associate CPU%d with a PMU\n",
+				    cpu);
+		return 0;
+	}
 
 	arm_pmu_acpi_associate_pmu_cpu(pmu, cpu);
-
-	/*
-	 * Ideally, we'd probe the PMU here when we find the first matching
-	 * CPU. We can't do that for several reasons; see the comment in
-	 * arm_pmu_acpi_init().
-	 *
-	 * So for the time being, we're done.
-	 */
 	return 0;
 }
 
+static void arm_pmu_acpi_probe_matching_cpus(struct arm_pmu *pmu,
+					     unsigned long cpuid)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		unsigned long cpu_cpuid = per_cpu(cpu_data, cpu).reg_midr;
+
+		if (cpu_cpuid == cpuid)
+			arm_pmu_acpi_associate_pmu_cpu(pmu, cpu);
+	}
+}
+
 int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
 {
 	int pmu_idx = 0;
-	int cpu, ret;
+	unsigned int cpu;
+	int ret;
+
+	ret = arm_pmu_acpi_parse_irqs();
+	if (ret)
+		return ret;
+
+	ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_ACPI_STARTING,
+					"perf/arm/pmu_acpi:starting",
+					arm_pmu_acpi_cpu_starting, NULL);
+	if (ret)
+		return ret;
 
 	/*
 	 * Initialise and register the set of PMUs which we know about right
@@ -320,13 +320,26 @@ int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
 	 * For the moment, as with the platform/DT case, we need at least one
 	 * of a PMU's CPUs to be online at probe time.
 	 */
-	for_each_possible_cpu(cpu) {
+	for_each_online_cpu(cpu) {
 		struct arm_pmu *pmu = per_cpu(probed_pmus, cpu);
+		unsigned long cpuid;
 		char *base_name;
 
-		if (!pmu || pmu->name)
+		/* If we've already probed this CPU, we have nothing to do */
+		if (pmu)
 			continue;
 
+		pmu = armpmu_alloc();
+		if (!pmu) {
+			pr_warn("Unable to allocate PMU for CPU%d\n",
+				cpu);
+		}
+
+		cpuid = per_cpu(cpu_data, cpu).reg_midr;
+		pmu->acpi_cpuid = cpuid;
+
+		arm_pmu_acpi_probe_matching_cpus(pmu, cpuid);
+
 		ret = init_fn(pmu);
 		if (ret == -ENODEV) {
 			/* PMU not handled by this driver, or not present */
@@ -351,26 +364,16 @@ int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
 		}
 	}
 
-	return 0;
+	return ret;
 }
 
 static int arm_pmu_acpi_init(void)
 {
-	int ret;
-
 	if (acpi_disabled)
 		return 0;
 
 	arm_spe_acpi_register_device();
 
-	ret = arm_pmu_acpi_parse_irqs();
-	if (ret)
-		return ret;
-
-	ret = cpuhp_setup_state(CPUHP_AP_PERF_ARM_ACPI_STARTING,
-				"perf/arm/pmu_acpi:starting",
-				arm_pmu_acpi_cpu_starting, NULL);
-
-	return ret;
+	return 0;
 }
 subsys_initcall(arm_pmu_acpi_init)