KVM: add basic paravirt support

Add basic KVM paravirt support. Avoid vm-exits on IO delays.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index a2f3274..76f0947 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -237,6 +237,7 @@
 #define KVM_CAP_NR_VCPUS 9       /* returns max vcpus per vm */
 #define KVM_CAP_NR_MEMSLOTS 10   /* returns max memory slots per vm */
 #define KVM_CAP_PIT 11
+#define KVM_CAP_NOP_IO_DELAY 12
 
 /*
  * ioctls for VM fds