libxl: use qemu-xen (upstream QEMU) as device model by default

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

docs/man/xl.cfg.pod.5

@@ -1176,15 +1176,15 @@ guest. Valid values are:
 
 =over 4
 
-=item B<qemu-xen-traditional>
-
-Use the device-model based upon the historical Xen fork of Qemu.  This
-device-model is currently the default.
-
 =item B<qemu-xen>
 
-use the device-model merged into the upstream QEMU project.  This
-device-model will become the default in a future version of Xen.
+Use the device-model merged into the upstream QEMU project.
+This device-model is the default for Linux dom0.
+
+=item B<qemu-xen-traditional>
+
+Use the device-model based upon the historical Xen fork of Qemu.
+This device-model is still the default for NetBSD dom0.
 
 =back
 

tools/libxl/libxl_create.c

@@ -105,9 +105,13 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
     libxl_defbool_setdefault(&b_info->device_model_stubdomain, false);
 
     if (!b_info->device_model_version) {
-        if (b_info->type == LIBXL_DOMAIN_TYPE_HVM) {
-            b_info->device_model_version =
-                LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+        if (b_info->type == LIBXL_DOMAIN_TYPE_HVM)
+            if (libxl_defbool_val(info->device_model_stubdomain)) {
+                b_info->device_model_version =
+                    LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+            } else {
+                b_info->device_model_version = libxl__default_device_model(gc);
+            }
         } else {
             b_info->device_model_version =
                 LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;

tools/libxl/libxl_internal.h

@@ -1561,6 +1561,8 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc *gc_opt, const char *s);
   /* Based on /local/domain/$domid/dm-version xenstore key
    * default is qemu xen traditional */
 _hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
+  /* Return the system-wide default device model */
+_hidden libxl_device_model_version libxl__default_device_model(libxl__gc *gc);
 
 /* Check how executes hotplug script currently */
 int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t);

tools/libxl/libxl_linux.c

@@ -267,3 +267,8 @@ int libxl__get_hotplug_script_info(libxl__gc *gc, libxl__device *dev,
 out:
     return rc;
 }
+
+libxl_device_model_version libxl__default_device_model(libxl__gc *gc)
+{
+    return LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
+}

tools/libxl/libxl_netbsd.c

@@ -90,3 +90,8 @@ int libxl__get_hotplug_script_info(libxl__gc *gc, libxl__device *dev,
 out:
     return rc;
 }
+
+libxl_device_model_version libxl__default_device_model(libxl__gc *gc)
+{
+    return LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+}