qemu: Build activeUsbHostdevs list on process reconnect

If the daemon is restarted it will lose list of active
USB devices assigned to active domains. Therefore we need
to rebuild this list on qemuProcessReconnect().
(cherry picked from commit ea3bc548ac)

src/qemu/qemu_hostdev.c

@@ -157,6 +157,46 @@ int qemuUpdateActivePciHostdevs(struct qemud_driver *driver,
     return 0;
 }
 
+int
+qemuUpdateActiveUsbHostdevs(struct qemud_driver *driver,
+                            virDomainDefPtr def)
+{
+    virDomainHostdevDefPtr hostdev = NULL;
+    int i;
+
+    if (!def->nhostdevs)
+        return 0;
+
+    for (i = 0; i < def->nhostdevs; i++) {
+        usbDevice *usb = NULL;
+        hostdev = def->hostdevs[i];
+
+        if (hostdev->mode != VIR_DOMAIN_HOSTDEV_MODE_SUBSYS)
+            continue;
+        if (hostdev->source.subsys.type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB)
+            continue;
+
+        usb = usbGetDevice(hostdev->source.subsys.u.usb.bus,
+                           hostdev->source.subsys.u.usb.device);
+        if (!usb) {
+            VIR_WARN("Unable to reattach USB device %03d.%03d on domain %s",
+                     hostdev->source.subsys.u.usb.bus,
+                     hostdev->source.subsys.u.usb.device,
+                     def->name);
+            continue;
+        }
+
+        usbDeviceSetUsedBy(usb, def->name);
+
+        if (usbDeviceListAdd(driver->activeUsbHostdevs, usb) < 0) {
+            usbFreeDevice(usb);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
 static int
 qemuDomainHostdevPciSysfsPath(virDomainHostdevDefPtr hostdev, char **sysfs_path)
 {

src/qemu/qemu_hostdev.h

@@ -29,6 +29,8 @@
 
 int qemuUpdateActivePciHostdevs(struct qemud_driver *driver,
                                 virDomainDefPtr def);
+int qemuUpdateActiveUsbHostdevs(struct qemud_driver *driver,
+                                virDomainDefPtr def);
 int qemuPrepareHostdevPCIDevices(struct qemud_driver *driver,
                                  const char *name,
                                  const unsigned char *uuid,

src/qemu/qemu_process.c

@@ -3057,6 +3057,9 @@ qemuProcessReconnect(void *opaque)
         goto error;
     }
 
+    if (qemuUpdateActiveUsbHostdevs(driver, obj->def) < 0)
+        goto error;
+
     if (qemuProcessUpdateState(driver, obj) < 0)
         goto error;