qemu: hotplug: Add support for signalling device unplug failure

Similarly to the DEVICE_DELETED event we will be able to tell when
unplug of certain device types will be rejected by the guest OS. Wire up
the device deletion signalling code to allow handling this.

src/qemu/qemu_domain.h

@@ -149,6 +149,22 @@ typedef void (*qemuDomainCleanupCallback)(virQEMUDriverPtr driver,
                                           virDomainObjPtr vm);
 
 # define QEMU_DOMAIN_MASTER_KEY_LEN 32  /* 32 bytes for 256 bit random key */
+
+
+/* helper data types for async device unplug */
+typedef enum {
+    QEMU_DOMAIN_UNPLUGGING_DEVICE_STATUS_NONE = 0,
+    QEMU_DOMAIN_UNPLUGGING_DEVICE_STATUS_OK,
+    QEMU_DOMAIN_UNPLUGGING_DEVICE_STATUS_GUEST_REJECTED,
+} qemuDomainUnpluggingDeviceStatus;
+
+typedef struct _qemuDomainUnpluggingDevice qemuDomainUnpluggingDevice;
+typedef qemuDomainUnpluggingDevice *qemuDomainUnpluggingDevicePtr;
+struct _qemuDomainUnpluggingDevice {
+    const char *alias;
+    qemuDomainUnpluggingDeviceStatus status;
+};
+
 typedef struct _qemuDomainObjPrivate qemuDomainObjPrivate;
 typedef qemuDomainObjPrivate *qemuDomainObjPrivatePtr;
 struct _qemuDomainObjPrivate {
@@ -199,7 +215,8 @@ struct _qemuDomainObjPrivate {
 
     virPerfPtr perf;
 
-    const char *unpluggingDevice; /* alias of the device that is being unplugged */
+    qemuDomainUnpluggingDevice unplug;
+
     char **qemuDevices; /* NULL-terminated list of devices aliases known to QEMU */
 
     bool hookRun;  /* true if there was a hook run over this domain */

src/qemu/qemu_hotplug.c

@@ -3334,20 +3334,24 @@ qemuDomainMarkDeviceForRemoval(virDomainObjPtr vm,
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
 
-    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE_DEL_EVENT))
-        priv->unpluggingDevice = info->alias;
-    else
-        priv->unpluggingDevice = NULL;
+    memset(&priv->unplug, 0, sizeof(priv->unplug));
+
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_DEVICE_DEL_EVENT))
+        return;
+
+    priv->unplug.alias = info->alias;
 }
 
 static void
 qemuDomainResetDeviceRemoval(virDomainObjPtr vm)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    priv->unpluggingDevice = NULL;
+    priv->unplug.alias = NULL;
 }
 
 /* Returns:
+ *  -1 Unplug of the device failed
+ *
  *   0 DEVICE_DELETED event is supported and removal of the device did not
  *     finish in qemuDomainRemoveDeviceWaitTime
  *
@@ -3370,17 +3374,23 @@ qemuDomainWaitForDeviceRemoval(virDomainObjPtr vm)
         return 1;
     until += qemuDomainRemoveDeviceWaitTime;
 
-    while (priv->unpluggingDevice) {
+    while (priv->unplug.alias) {
         if ((rc = virDomainObjWaitUntil(vm, until)) == 1)
             return 0;
 
         if (rc < 0) {
             VIR_WARN("Failed to wait on unplug condition for domain '%s' "
-                     "device '%s'", vm->def->name, priv->unpluggingDevice);
+                     "device '%s'", vm->def->name, priv->unplug.alias);
             return 1;
         }
     }
 
+    if (priv->unplug.status == QEMU_DOMAIN_UNPLUGGING_DEVICE_STATUS_GUEST_REJECTED) {
+        virReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                       _("unplug of device was rejected by the guest"));
+        return -1;
+    }
+
     return 1;
 }
 
@@ -3392,12 +3402,14 @@ qemuDomainWaitForDeviceRemoval(virDomainObjPtr vm)
  */
 bool
 qemuDomainSignalDeviceRemoval(virDomainObjPtr vm,
-                              const char *devAlias)
+                              const char *devAlias,
+                              qemuDomainUnpluggingDeviceStatus status)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
 
-    if (STREQ_NULLABLE(priv->unpluggingDevice, devAlias)) {
+    if (STREQ_NULLABLE(priv->unplug.alias, devAlias)) {
         qemuDomainResetDeviceRemoval(vm);
+        priv->unplug.status = status;
         virDomainObjBroadcast(vm);
         return true;
     }

src/qemu/qemu_hotplug.h

@@ -122,6 +122,7 @@ int qemuDomainRemoveDevice(virQEMUDriverPtr driver,
                            virDomainDeviceDefPtr dev);
 
 bool qemuDomainSignalDeviceRemoval(virDomainObjPtr vm,
-                                   const char *devAlias);
+                                   const char *devAlias,
+                                   qemuDomainUnpluggingDeviceStatus status);
 
 #endif /* __QEMU_HOTPLUG_H__ */

src/qemu/qemu_process.c

@@ -1359,7 +1359,8 @@ qemuProcessHandleDeviceDeleted(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
     VIR_DEBUG("Device %s removed from domain %p %s",
               devAlias, vm, vm->def->name);
 
-    if (qemuDomainSignalDeviceRemoval(vm, devAlias))
+    if (qemuDomainSignalDeviceRemoval(vm, devAlias,
+                                      QEMU_DOMAIN_UNPLUGGING_DEVICE_STATUS_OK))
         goto cleanup;
 
     if (VIR_ALLOC(processEvent) < 0)