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>

drivers/kvm/kvm_main.c

@@ -2054,12 +2054,21 @@ static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
 	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();
 
 	/*