KVM: Avoid saving and restoring some host CPU state on lightweight vmexit

Many msrs and the like will only be used by the host if we schedule() or
return to userspace.  Therefore, we avoid saving them if we handle the
exit within the kernel, and if a reschedule is not requested.

Based on a patch from Eddie Dong <eddie.dong@intel.com> with a couple of
fixes by me.

Signed-off-by: Yaozu(Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 152312c1fafa..7facebd1911d 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -252,6 +252,7 @@ struct kvm_stat {
         u32 halt_exits;
         u32 request_irq_exits;
         u32 irq_exits;
+        u32 light_exits;
 };
 
 struct kvm_vcpu {