KVM: Move kvm_guest_exit() after local_irq_enable()

We need to make sure that the timer interrupt happens before we clear
PF_VCPU, so the accounting code actually sees guest mode.

http://lkml.org/lkml/2007/10/15/114

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index af2d288c881d..8c458f262872 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2054,12 +2054,21 @@ again:
 
         kvm_x86_ops->run(vcpu, kvm_run);
 
-        kvm_guest_exit();
         vcpu->guest_mode = 0;
         local_irq_enable();
 
         ++vcpu->stat.exits;
 
+        /*
+         * We must have an instruction between local_irq_enable() and
+         * kvm_guest_exit(), so the timer interrupt isn't delayed by
+         * the interrupt shadow.  The stat.exits increment will do nicely.
+         * But we need to prevent reordering, hence this barrier():
+         */
+        barrier();
+
+        kvm_guest_exit();
+
         preempt_enable();
 
         /*