diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h
index f830bdd4ad..614ff5f2b4 100644
--- a/xen/include/public/hvm/params.h
+++ b/xen/include/public/hvm/params.h
@@ -148,6 +148,9 @@
 #define HVM_PARAM_IOREQ_SERVER_PFN 32
 #define HVM_PARAM_NR_IOREQ_SERVER_PAGES 33
 
-#define HVM_NR_PARAMS          34
+/* Location of the VM Generation ID in guest physical address space. */
+#define HVM_PARAM_VM_GENERATION_ID_ADDR 34
+
+#define HVM_NR_PARAMS          35
 
 #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */