[PATCH 17/18] KVM: ARM64: Add PMU overflow interrupt routing

[shannon.zhao at linaro.org]

From: Shannon Zhao <shannon.zhao at linaro.org>

When calling perf_event_create_kernel_counter to create perf_event,
assign a overflow handler. Then when perf event overflows, if vcpu
doesn't run, call irq_work_queue to wake up vcpu. Otherwise call
kvm_vgic_inject_irq to inject the interrupt.

Signed-off-by: Shannon Zhao <shannon.zhao at linaro.org>
---
 arch/arm/kvm/arm.c    |  2 ++
 include/kvm/arm_pmu.h |  2 ++
 virt/kvm/arm/pmu.c    | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 4e82625..41eb063 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -551,6 +551,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 			preempt_enable();
 			kvm_timer_sync_hwstate(vcpu);
 			kvm_vgic_sync_hwstate(vcpu);
+			kvm_pmu_sync_hwstate(vcpu);
 			continue;
 		}
 
@@ -595,6 +596,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 		kvm_timer_sync_hwstate(vcpu);
 		kvm_vgic_sync_hwstate(vcpu);
+		kvm_pmu_sync_hwstate(vcpu);
 
 		ret = handle_exit(vcpu, run, ret);
 	}
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 6985809..5bcf27b 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -45,6 +45,7 @@ struct kvm_pmu {
 };
 
 #ifdef CONFIG_KVM_ARM_PMU
+void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu);
 void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu);
 void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, unsigned long select_idx,
 			       unsigned long val);
@@ -59,6 +60,7 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
 				    unsigned long select_idx);
 void kvm_pmu_init(struct kvm_vcpu *vcpu);
 #else
+void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu) {}
 static inline void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) {}
 void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, unsigned long select_idx,
 			       unsigned long val) {}
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index e655426..f957b85 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -20,6 +20,7 @@
 #include <linux/kvm_host.h>
 #include <linux/perf_event.h>
 #include <kvm/arm_pmu.h>
+#include <kvm/arm_vgic.h>
 
 /* PMU HW events mapping. */
 static struct kvm_pmu_hw_event_map {
@@ -81,6 +82,23 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu,
 }
 
 /**
+ * kvm_pmu_sync_hwstate - sync pmu state for cpu
+ * @vcpu: The vcpu pointer
+ *
+ * Inject virtual PMU IRQ if IRQ is pending for this cpu.
+ */
+void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu)
+{
+	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+
+	if (pmu->irq_pending) {
+		kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id, pmu->irq_num, 1);
+		pmu->irq_pending = 0;
+		return;
+	}
+}
+
+/**
  * kvm_pmu_vcpu_reset - reset pmu state for cpu
  * @vcpu: The vcpu pointer
  *
@@ -96,6 +114,37 @@ void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu)
 	pmu->irq_pending = false;
 }
 
+static void kvm_pum_trigger_pmi(struct irq_work *irq_work)
+{
+	struct kvm_pmu *pmu = container_of(irq_work, struct kvm_pmu, irq_work);
+	struct kvm_vcpu *vcpu = container_of(pmu, struct kvm_vcpu, arch.pmu);
+
+	kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id, pmu->irq_num, 1);
+}
+
+/**
+ * When perf event overflows, if vcpu doesn't run, call irq_work_queue to wake
+ * up vcpu. Otherwise call kvm_vgic_inject_irq to inject the interrupt.
+ */
+static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
+				  struct perf_sample_data *data,
+				  struct pt_regs *regs)
+{
+	struct kvm_pmc *pmc = perf_event->overflow_handler_context;
+	struct kvm_vcpu *vcpu = pmc->vcpu;
+	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+
+	if (pmc->interrupt == true) {
+		__set_bit(pmc->idx, (unsigned long *)&pmu->overflow_status);
+		pmu->irq_pending = 1;
+		if (vcpu->mode != IN_GUEST_MODE)
+			irq_work_queue(&pmu->irq_work);
+		else
+			kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+					    pmu->irq_num, 1);
+	}
+}
+
 /**
  * kvm_pmu_set_counter_value - set PMU counter value
  * @vcpu: The vcpu pointer
@@ -322,7 +371,8 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
 	attr.config = config;
 	attr.sample_period = (-pmc->counter) & (((u64)1 << 32) - 1);
 
-	event = perf_event_create_kernel_counter(&attr, -1, current, NULL, pmc);
+	event = perf_event_create_kernel_counter(&attr, -1, current,
+						 kvm_pmu_perf_overflow, pmc);
 	if (IS_ERR(event)) {
 		kvm_err("kvm: pmu event creation failed %ld\n",
 			  PTR_ERR(event));
@@ -351,4 +401,5 @@ void kvm_pmu_init(struct kvm_vcpu *vcpu)
 	}
 
 	pmu->irq_num = -1;
+	init_irq_work(&pmu->irq_work, kvm_pum_trigger_pmi);
 }
-- 
2.1.0