libxl: Check for libxl_ctx_alloc failure

src/libxl/libxl_driver.c

@@ -269,7 +269,12 @@ libxlDomainObjPrivateAlloc(void)
     if (VIR_ALLOC(priv) < 0)
         return NULL;
 
-    libxl_ctx_alloc(&priv->ctx, LIBXL_VERSION, 0, libxl_driver->logger);
+    if (libxl_ctx_alloc(&priv->ctx, LIBXL_VERSION, 0, libxl_driver->logger)) {
+        VIR_ERROR(_("Failed libxl context initialization"));
+        VIR_FREE(priv);
+        return NULL;
+    }
+
     libxl_osevent_register_hooks(priv->ctx, &libxl_event_callbacks, priv);
 
     return priv;