linux-kernel - [PATCH v12 35/46] HACK: Restore per-CPU cpu

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Message-ID: <20251217101125.91098-36-steven.price@arm.com>
Date: Wed, 17 Dec 2025 10:11:12 +0000
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
	Emi Kisanuki <fj0570is@...itsu.com>,
	Vishal Annapurve <vannapurve@...gle.com>
Subject: [PATCH v12 35/46] HACK: Restore per-CPU cpu_armpmu pointer

Commit fa9d27773873 ("perf: arm_pmu: Kill last use of per-CPU cpu_armpmu
pointer") removed the per-CPU cpu_armpmu. Rather than refactoring the
code to deal with this just reintroduce it. The CCA PMU code will be
changing when switching to the RMM v2.0 ABI and will need completely
reworking.

Signed-off-by: Steven Price <steven.price@....com>
---
 drivers/perf/arm_pmu.c       | 5 +++++
 include/linux/perf/arm_pmu.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 973a027d9063..c94494db06f5 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -104,6 +104,7 @@ static const struct pmu_irq_ops percpu_pmunmi_ops = {
 	.free_pmuirq = armpmu_free_percpu_pmunmi
 };
 
+DEFINE_PER_CPU(struct arm_pmu *, cpu_armpmu);
 static DEFINE_PER_CPU(int, cpu_irq);
 static DEFINE_PER_CPU(const struct pmu_irq_ops *, cpu_irq_ops);
 
@@ -724,6 +725,8 @@ static int arm_perf_starting_cpu(unsigned int cpu, struct hlist_node *node)
 	if (pmu->reset)
 		pmu->reset(pmu);
 
+	per_cpu(cpu_armpmu, cpu) = pmu;
+
 	irq = armpmu_get_cpu_irq(pmu, cpu);
 	if (irq)
 		per_cpu(cpu_irq_ops, cpu)->enable_pmuirq(irq);
@@ -743,6 +746,8 @@ static int arm_perf_teardown_cpu(unsigned int cpu, struct hlist_node *node)
 	if (irq)
 		per_cpu(cpu_irq_ops, cpu)->disable_pmuirq(irq);
 
+	per_cpu(cpu_armpmu, cpu) = NULL;
+
 	return 0;
 }
 
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 52b37f7bdbf9..e1be4a6c8b43 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -133,6 +133,8 @@ struct arm_pmu {
 
 #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu))
 
+DECLARE_PER_CPU(struct arm_pmu *, cpu_armpmu);
+
 u64 armpmu_event_update(struct perf_event *event);
 
 int armpmu_event_set_period(struct perf_event *event);
-- 
2.43.0