Xen queue

* Fixes for xen-bus and exit cleanup.
 * Build fix.
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Merge remote-tracking branch 'remotes/aperard/tags/pull-xen-20190827' into staging

Xen queue

* Fixes for xen-bus and exit cleanup.
* Build fix.

# gpg: Signature made Tue 27 Aug 2019 14:31:10 BST
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# gpg:                issuer "anthony.perard@citrix.com"
# gpg: Good signature from "Anthony PERARD <anthony.perard@gmail.com>" [marginal]
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# Primary key fingerprint: 5379 2F71 024C 600F 778A  7161 D8D5 7199 DF83 42C8
#      Subkey fingerprint: F80C 0063 08E2 2CFD 8A92  E798 0CF5 572F D7FB 55AF

* remotes/aperard/tags/pull-xen-20190827:
  xen-bus: Avoid rewriting identical values to xenstore
  xen-bus: Fix backend state transition on device reset
  xen: cleanup IOREQ server on exit
  xen: Fix ring.h header

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/i386/xen/xen-hvm.c

@@ -1247,6 +1247,8 @@ static void xen_exit_notifier(Notifier *n, void *data)
 {
     XenIOState *state = container_of(n, XenIOState, exit);
 
+    xen_destroy_ioreq_server(xen_domid, state->ioservid);
+
     xenevtchn_close(state->xce_handle);
     xs_daemon_close(state->xenstore);
 }

hw/xen/xen-bus.c

@@ -516,6 +516,23 @@ static void xen_device_backend_set_online(XenDevice *xendev, bool online)
     xen_device_backend_printf(xendev, "online", "%u", online);
 }
 
+/*
+ * Tell from the state whether the frontend is likely alive,
+ * i.e. it will react to a change of state of the backend.
+ */
+static bool xen_device_state_is_active(enum xenbus_state state)
+{
+    switch (state) {
+    case XenbusStateInitWait:
+    case XenbusStateInitialised:
+    case XenbusStateConnected:
+    case XenbusStateClosing:
+        return true;
+    default:
+        return false;
+    }
+}
+
 static void xen_device_backend_changed(void *opaque)
 {
     XenDevice *xendev = opaque;
@@ -539,11 +556,11 @@ static void xen_device_backend_changed(void *opaque)
 
     /*
      * If the toolstack (or unplug request callback) has set the backend
-     * state to Closing, but there is no active frontend (i.e. the
+     * state to Closing, but there is no active frontend then set the
-     * state is not Connected) then set the backend state to Closed.
+     * backend state to Closed.
      */
     if (xendev->backend_state == XenbusStateClosing &&
-        xendev->frontend_state != XenbusStateConnected) {
+        !xen_device_state_is_active(state)) {
         xen_device_backend_set_state(xendev, XenbusStateClosed);
     }
 
@@ -681,7 +698,8 @@ int xen_device_frontend_scanf(XenDevice *xendev, const char *key,
 }
 
 static void xen_device_frontend_set_state(XenDevice *xendev,
-                                          enum xenbus_state state)
+                                          enum xenbus_state state,
+                                          bool publish)
 {
     const char *type = object_get_typename(OBJECT(xendev));
 
@@ -693,7 +711,9 @@ static void xen_device_frontend_set_state(XenDevice *xendev,
                                     xs_strstate(state));
 
     xendev->frontend_state = state;
-    xen_device_frontend_printf(xendev, "state", "%u", state);
+    if (publish) {
+        xen_device_frontend_printf(xendev, "state", "%u", state);
+    }
 }
 
 static void xen_device_frontend_changed(void *opaque)
@@ -709,7 +729,7 @@ static void xen_device_frontend_changed(void *opaque)
         state = XenbusStateUnknown;
     }
 
-    xen_device_frontend_set_state(xendev, state);
+    xen_device_frontend_set_state(xendev, state, false);
 
     if (state == XenbusStateInitialising &&
         xendev->backend_state == XenbusStateClosed &&
@@ -1152,7 +1172,7 @@ static void xen_device_realize(DeviceState *dev, Error **errp)
     xen_device_frontend_printf(xendev, "backend-id", "%u",
                                xenbus->backend_id);
 
-    xen_device_frontend_set_state(xendev, XenbusStateInitialising);
+    xen_device_frontend_set_state(xendev, XenbusStateInitialising, true);
 
     xendev->exit.notify = xen_device_exit;
     qemu_add_exit_notifier(&xendev->exit);

include/hw/xen/interface/io/ring.h

@@ -33,6 +33,13 @@
  * - standard integers types (uint8_t, uint16_t, etc)
  * They are provided by stdint.h of the standard headers.
  *
+ * Before using the different macros, you need to provide the following
+ * macros:
+ * - xen_mb()  a memory barrier
+ * - xen_rmb() a read memory barrier
+ * - xen_wmb() a write memory barrier
+ * Example of those can be found in xenctrl.h.
+ *
  * In addition, if you intend to use the FLEX macros, you also need to
  * provide the following, before invoking the FLEX macros:
  * - size_t
@@ -42,12 +49,6 @@
  * and grant_table.h from the Xen public headers.
  */
 
-#if __XEN_INTERFACE_VERSION__ < 0x00030208
-#define xen_mb()  mb()
-#define xen_rmb() rmb()
-#define xen_wmb() wmb()
-#endif
-
 typedef unsigned int RING_IDX;
 
 /* Round a 32-bit unsigned constant down to the nearest power of two. */