1 files changed, 82 insertions, 0 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6973483d0dfa..5a2166ba6138 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5656,6 +5656,8 @@ static void __free_event(struct perf_event *event)
 	call_rcu(&event->rcu_head, free_event_rcu);
 }
 
+static void mediated_pmu_unaccount_event(struct perf_event *event);
+
 DEFINE_FREE(__free_event, struct perf_event *, if (_T) __free_event(_T))
 
 /* vs perf_event_alloc() success */
@@ -5665,6 +5667,7 @@ static void _free_event(struct perf_event *event)
 	irq_work_sync(&event->pending_disable_irq);
 
 	unaccount_event(event);
+	mediated_pmu_unaccount_event(event);
 
 	if (event->rb) {
 		/*
@@ -6187,6 +6190,81 @@ u64 perf_event_pause(struct perf_event *event, bool reset)
 }
 EXPORT_SYMBOL_GPL(perf_event_pause);
 
+#ifdef CONFIG_PERF_GUEST_MEDIATED_PMU
+static atomic_t nr_include_guest_events __read_mostly;
+
+static atomic_t nr_mediated_pmu_vms __read_mostly;
+static DEFINE_MUTEX(perf_mediated_pmu_mutex);
+
+/* !exclude_guest event of PMU with PERF_PMU_CAP_MEDIATED_VPMU */
+static inline bool is_include_guest_event(struct perf_event *event)
+{
+	if ((event->pmu->capabilities & PERF_PMU_CAP_MEDIATED_VPMU) &&
+	    !event->attr.exclude_guest)
+		return true;
+
+	return false;
+}
+
+static int mediated_pmu_account_event(struct perf_event *event)
+{
+	if (!is_include_guest_event(event))
+		return 0;
+
+	guard(mutex)(&perf_mediated_pmu_mutex);
+
+	if (atomic_read(&nr_mediated_pmu_vms))
+		return -EOPNOTSUPP;
+
+	atomic_inc(&nr_include_guest_events);
+	return 0;
+}
+
+static void mediated_pmu_unaccount_event(struct perf_event *event)
+{
+	if (!is_include_guest_event(event))
+		return;
+
+	atomic_dec(&nr_include_guest_events);
+}
+
+/*
+ * Currently invoked at VM creation to
+ * - Check whether there are existing !exclude_guest events of PMU with
+ *   PERF_PMU_CAP_MEDIATED_VPMU
+ * - Set nr_mediated_pmu_vms to prevent !exclude_guest event creation on
+ *   PMUs with PERF_PMU_CAP_MEDIATED_VPMU
+ *
+ * No impact for the PMU without PERF_PMU_CAP_MEDIATED_VPMU. The perf
+ * still owns all the PMU resources.
+ */
+int perf_create_mediated_pmu(void)
+{
+	guard(mutex)(&perf_mediated_pmu_mutex);
+	if (atomic_inc_not_zero(&nr_mediated_pmu_vms))
+		return 0;
+
+	if (atomic_read(&nr_include_guest_events))
+		return -EBUSY;
+
+	atomic_inc(&nr_mediated_pmu_vms);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_create_mediated_pmu);
+
+void perf_release_mediated_pmu(void)
+{
+	if (WARN_ON_ONCE(!atomic_read(&nr_mediated_pmu_vms)))
+		return;
+
+	atomic_dec(&nr_mediated_pmu_vms);
+}
+EXPORT_SYMBOL_GPL(perf_release_mediated_pmu);
+#else
+static int mediated_pmu_account_event(struct perf_event *event) { return 0; }
+static void mediated_pmu_unaccount_event(struct perf_event *event) {}
+#endif
+
 /*
  * Holding the top-level event's child_mutex means that any
  * descendant process that has inherited this event will block
@@ -13147,6 +13225,10 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 	if (err)
 		return ERR_PTR(err);
 
+	err = mediated_pmu_account_event(event);
+	if (err)
+		return ERR_PTR(err);
+
 	/* symmetric to unaccount_event() in _free_event() */
 	account_event(event);