From 82a29e304841e464ddb6a8a2c0240196b0ee3887 Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Tue, 8 Jan 2019 14:48:50 +0000 Subject: xen: add xenstore watcher infrastructure A Xen PV frontend communicates its state to the PV backend by writing to the 'state' key in the frontend area in xenstore. It is therefore necessary for a XenDevice implementation to be notified whenever the value of this key changes. This patch adds code to do this as follows: - an 'fd handler' is registered on the libxenstore handle which will be triggered whenever a 'watch' event occurs - primitives are added to xen-bus-helper to add or remove watch events - a list of Notifier objects is added to XenBus to provide a mechanism to call the appropriate 'watch handler' when its associated event occurs The xen-block implementation is extended with a 'frontend_changed' method, which calls as-yet stub 'connect' and 'disconnect' functions when the relevant frontend state transitions occur. A subsequent patch will supply a full implementation for these functions. Signed-off-by: Paul Durrant Reviewed-by: Anthony Perard Signed-off-by: Anthony PERARD --- include/hw/xen/xen-bus.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/hw/xen/xen-bus.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 */ -- cgit v1.2.3