2 files changed, 21 insertions, 0 deletions
diff --git a/include/hw/xen/xen-bus-helper.h b/include/hw/xen/xen-bus-helper.h
index 5cd9c3d759..4c0f747445 100644
--- a/include/hw/xen/xen-bus-helper.h
+++ b/include/hw/xen/xen-bus-helper.h
@@ -36,4 +36,10 @@ int xs_node_scanf(struct xs_handle *xsh,  xs_transaction_t tid,
                   const char *node, const char *key, Error **errp,
                   const char *fmt, ...);
 
+/* Watch node/key unless node is empty, in which case watch key */
+void xs_node_watch(struct xs_handle *xsh, const char *node, const char *key,
+                   char *token, Error **errp);
+void xs_node_unwatch(struct xs_handle *xsh, const char *node, const char *key,
+                     const char *token, Error **errp);
+
 #endif /* HW_XEN_BUS_HELPER_H */
diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h
index 85a75d8dec..df73674fcd 100644
--- a/include/hw/xen/xen-bus.h
+++ b/include/hw/xen/xen-bus.h
@@ -10,6 +10,11 @@
 
 #include "hw/xen/xen_common.h"
 #include "hw/sysbus.h"
+#include "qemu/notify.h"
+
+typedef void (*XenWatchHandler)(void *opaque);
+
+typedef struct XenWatch XenWatch;
 
 typedef struct XenDevice {
     DeviceState qdev;
@@ -18,10 +23,14 @@ typedef struct XenDevice {
     char *backend_path, *frontend_path;
     enum xenbus_state backend_state, frontend_state;
     Notifier exit;
+    XenWatch *frontend_state_watch;
 } XenDevice;
 
 typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp);
 typedef void (*XenDeviceRealize)(XenDevice *xendev, Error **errp);
+typedef void (*XenDeviceFrontendChanged)(XenDevice *xendev,
+                                         enum xenbus_state frontend_state,
+                                         Error **errp);
 typedef void (*XenDeviceUnrealize)(XenDevice *xendev, Error **errp);
 
 typedef struct XenDeviceClass {
@@ -32,6 +41,7 @@ typedef struct XenDeviceClass {
     const char *device;
     XenDeviceGetName get_name;
     XenDeviceRealize realize;
+    XenDeviceFrontendChanged frontend_changed;
     XenDeviceUnrealize unrealize;
 } XenDeviceClass;
 
@@ -47,6 +57,7 @@ typedef struct XenBus {
     BusState qbus;
     domid_t backend_id;
     struct xs_handle *xsh;
+    NotifierList watch_notifiers;
 } XenBus;
 
 typedef struct XenBusClass {
@@ -64,4 +75,8 @@ typedef struct XenBusClass {
 
 void xen_bus_init(void);
 
+void xen_device_backend_set_state(XenDevice *xendev,
+                                  enum xenbus_state state);
+enum xenbus_state xen_device_backend_get_state(XenDevice *xendev);
+
 #endif /* HW_XEN_BUS_H */