Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Except for the preempt notifiers fix, these are all small bugfixes
  that could have been waited for -rc2.  Sending them now since I was
  taking care of Peter's patch anyway"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: add hyper-v crash msrs values
  KVM: x86: remove data variable from kvm_get_msr_common
  KVM: s390: virtio-ccw: don't overwrite config space values
  KVM: x86: keep track of LVT0 changes under APICv
  KVM: x86: properly restore LVT0
  KVM: x86: make vapics_in_nmi_mode atomic
  sched, preempt_notifier: separate notifier registration from static_key inc/dec

1 files changed, 15 insertions, 2 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5caa029dec5d..78b4bad10081 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2320,13 +2320,27 @@ void wake_up_new_task(struct task_struct *p)
 
 static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
 
+void preempt_notifier_inc(void)
+{
+	static_key_slow_inc(&preempt_notifier_key);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_inc);
+
+void preempt_notifier_dec(void)
+{
+	static_key_slow_dec(&preempt_notifier_key);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_dec);
+
 /**
  * preempt_notifier_register - tell me when current is being preempted & rescheduled
  * @notifier: notifier struct to register
  */
 void preempt_notifier_register(struct preempt_notifier *notifier)
 {
-	static_key_slow_inc(&preempt_notifier_key);
+	if (!static_key_false(&preempt_notifier_key))
+		WARN(1, "registering preempt_notifier while notifiers disabled\n");
+
 	hlist_add_head(&notifier->link, &current->preempt_notifiers);
 }
 EXPORT_SYMBOL_GPL(preempt_notifier_register);
@@ -2340,7 +2354,6 @@ EXPORT_SYMBOL_GPL(preempt_notifier_register);
 void preempt_notifier_unregister(struct preempt_notifier *notifier)
 {
 	hlist_del(&notifier->link);
-	static_key_slow_dec(&preempt_notifier_key);
 }
 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);