[PATCH 2/2] KVM: make guest mode entry to be rcu quiescent state

[Gleb Natapov <gleb@redhat.com>]

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>
---
 include/linux/kvm_host.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0bc3d37..a347bce 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -593,6 +593,7 @@ static inline void kvm_guest_enter(void)
 {
 	account_system_vtime(current);
 	current->flags |= PF_VCPU;
+	rcu_note_context_switch(smp_processor_id());
 }
 
 static inline void kvm_guest_exit(void)
-- 
1.7.2.3