qemu: Fix USB by product with security enabled

We need to call PrepareHostdevs to determine the USB device path before
any security calls. PrepareHostUSBDevices was also incorrectly skipping
all USB devices.

src/qemu/qemu_driver.c

@@ -2360,7 +2360,7 @@ qemuPrepareHostUSBDevices(struct qemud_driver *driver ATTRIBUTE_UNUSED,
 
         if (hostdev->mode != VIR_DOMAIN_HOSTDEV_MODE_SUBSYS)
             continue;
-        if (hostdev->source.subsys.type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI)
+        if (hostdev->source.subsys.type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB)
             continue;
 
         /* Resolve a vendor/product to bus/device */
@@ -2703,6 +2703,11 @@ static int qemudStartVMDaemon(virConnectPtr conn,
         return -1;
     }
 
+    /* Must be run before security labelling */
+    DEBUG0("Preparing host devices");
+    if (qemuPrepareHostDevices(driver, vm->def) < 0)
+        goto cleanup;
+
     /* If you are using a SecurityDriver with dynamic labelling,
        then generate a security label for isolation */
     DEBUG0("Generating domain security label (if required)");
@@ -2769,10 +2774,6 @@ static int qemudStartVMDaemon(virConnectPtr conn,
     if (qemuSetupCgroup(driver, vm) < 0)
         goto cleanup;
 
-    DEBUG0("Preparing host devices");
-    if (qemuPrepareHostDevices(driver, vm->def) < 0)
-        goto cleanup;
-
     if (VIR_ALLOC(priv->monConfig) < 0) {
         virReportOOMError();
         goto cleanup;