KVM: make guest mode entry to be rcu quiescent state
KVM does not hold any references to rcu protected data when it switches
CPU into a guest mode. In fact switching to a guest mode is very similar
to exiting to userspase from rcu point of view. In addition CPU may stay
in a guest mode for quite a long time (up to one time slice). Lets treat
guest mode as quiescent state, just like we do with user-mode execution.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0bc3d37..b9c3299 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -591,8 +591,17 @@
static inline void kvm_guest_enter(void)
{
+ BUG_ON(preemptible());
account_system_vtime(current);
current->flags |= PF_VCPU;
+ /* KVM does not hold any references to rcu protected data when it
+ * switches CPU into a guest mode. In fact switching to a guest mode
+ * is very similar to exiting to userspase from rcu point of view. In
+ * addition CPU may stay in a guest mode for quite a long time (up to
+ * one time slice). Lets treat guest mode as quiescent state, just like
+ * we do with user-mode execution.
+ */
+ rcu_virt_note_context_switch(smp_processor_id());
}
static inline void kvm_guest_exit(void)