[PATCH v7 32/45] arm_pmu: Provide a mechanism for disabling the physical IRQ

Steven Price
2025-02-13T16:17:08Z

Arm CCA assigns the physical PMU device to the guest running in realm
world, however the IRQs are routed via the host. To enter a realm guest
while a PMU IRQ is pending it is necessary to block the physical IRQ to
prevent an immediate exit. Provide a mechanism in the PMU driver for KVM
to control the physical IRQ.

Signed-off-by: Steven Price <steven.price@arm.com>
---
v3: Add a dummy function for the !CONFIG_ARM_PMU case.
---
drivers/perf/arm_pmu.c | 15 +++++++++++++++
include/linux/perf/arm_pmu.h | 5 +++++
2 files changed, 20 insertions(+)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 398cce3d76fc..2cdcdda8f638 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -735,6 +735,21 @@ static int arm_perf_teardown_cpu(unsigned int cpu, struct hlist_node *node)
return 0;
}

+void arm_pmu_set_phys_irq(bool enable)
+{
+ int cpu = get_cpu();
+ struct arm_pmu *pmu = per_cpu(cpu_armpmu, cpu);
+ int irq;
+
+ irq = armpmu_get_cpu_irq(pmu, cpu);
+ if (irq && !enable)
+ per_cpu(cpu_irq_ops, cpu)->disable_pmuirq(irq);
+ else if (irq && enable)
+ per_cpu(cpu_irq_ops, cpu)->enable_pmuirq(irq);
+
+ put_cpu();
+}
+
#ifdef CONFIG_CPU_PM
static void cpu_pm_pmu_setup(struct arm_pmu *armpmu, unsigned long cmd)
{
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 4b5b83677e3f..6c2631e2cbd7 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -172,6 +172,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu);
#endif

bool arm_pmu_irq_is_nmi(void);
+void arm_pmu_set_phys_irq(bool enable);

/* Internal functions only for core arm_pmu code */
struct arm_pmu *armpmu_alloc(void);
@@ -182,6 +183,10 @@ void armpmu_free_irq(int irq, int cpu);

#define ARMV8_PMU_PDEV_NAME "armv8-pmu"

+#else /* CONFIG_ARM_PMU */
+
+static inline void arm_pmu_set_phys_irq(bool enable) {}
+
#endif /* CONFIG_ARM_PMU */

#define ARMV8_SPE_PDEV_NAME "arm,spe-v1"
--
2.43.0