From: Julien Thierry <[email protected]>
kvm_vcpu_kick() is not NMI safe. When the overflow handler is called from
NMI context, defer waking the vcpu to an irq_work queue.
Cc: Julien Thierry <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: James Morse <[email protected]>
Cc: Suzuki K Pouloze <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Julien Thierry <[email protected]>
Signed-off-by: Alexandru Elisei <[email protected]>
---
arch/arm64/kvm/pmu-emul.c | 25 ++++++++++++++++++++++++-
include/kvm/arm_pmu.h | 1 +
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index f0d0312c0a55..30268397ed06 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -433,6 +433,22 @@ void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu)
kvm_pmu_update_state(vcpu);
}
+/**
+ * When perf interrupt is an NMI, we cannot safely notify the vcpu corresponding
+ * to the event.
+ * This is why we need a callback to do it once outside of the NMI context.
+ */
+static void kvm_pmu_perf_overflow_notify_vcpu(struct irq_work *work)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_pmu *pmu;
+
+ pmu = container_of(work, struct kvm_pmu, overflow_work);
+ vcpu = kvm_pmc_to_vcpu(&pmu->pmc[0]);
+
+ kvm_vcpu_kick(vcpu);
+}
+
/**
* When the perf event overflows, set the overflow status and inform the vcpu.
*/
@@ -465,7 +481,11 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
if (kvm_pmu_overflow_status(vcpu)) {
kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
- kvm_vcpu_kick(vcpu);
+
+ if (!in_nmi())
+ kvm_vcpu_kick(vcpu);
+ else
+ irq_work_queue(&vcpu->arch.pmu.overflow_work);
}
cpu_pmu->pmu.start(perf_event, PERF_EF_RELOAD);
@@ -764,6 +784,9 @@ static int kvm_arm_pmu_v3_init(struct kvm_vcpu *vcpu)
return ret;
}
+ init_irq_work(&vcpu->arch.pmu.overflow_work,
+ kvm_pmu_perf_overflow_notify_vcpu);
+
vcpu->arch.pmu.created = true;
return 0;
}
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 6db030439e29..dbf4f08d42e5 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -27,6 +27,7 @@ struct kvm_pmu {
bool ready;
bool created;
bool irq_level;
+ struct irq_work overflow_work;
};
#define kvm_arm_pmu_v3_ready(v) ((v)->arch.pmu.ready)
--
2.27.0