diff --git a/nova/conf/configdrive.py b/nova/conf/configdrive.py
index f19a825d910e..bb5cc514d8bf 100644
--- a/nova/conf/configdrive.py
+++ b/nova/conf/configdrive.py
@@ -56,7 +56,8 @@ Force injection to take place on a config drive
 
 When this option is set to true configuration drive functionality will be
 forced enabled by default, otherwise user can still enable configuration
-drives via the REST API or image metadata properties.
+drives via the REST API or image metadata properties. Launched VMs are not
+affected by this option.
 
 Possible values:
 
diff --git a/nova/tests/unit/virt/libvirt/test_blockinfo.py b/nova/tests/unit/virt/libvirt/test_blockinfo.py
index 022a85abb9aa..c2992308a3fe 100644
--- a/nova/tests/unit/virt/libvirt/test_blockinfo.py
+++ b/nova/tests/unit/virt/libvirt/test_blockinfo.py
@@ -55,6 +55,7 @@ class LibvirtBlockInfoTest(test.NoDBTestCase):
             'ephemeral_gb': 20,
             'instance_type_id': 2,  # m1.tiny
             'config_drive': None,
+            'launched_at': None,
             'system_metadata': {},
         }
         self.test_image_meta = {
diff --git a/nova/tests/unit/virt/test_configdrive.py b/nova/tests/unit/virt/test_configdrive.py
index 91962d1d7e1c..b5946671f168 100644
--- a/nova/tests/unit/virt/test_configdrive.py
+++ b/nova/tests/unit/virt/test_configdrive.py
@@ -42,11 +42,12 @@ class ConfigDriveTestCase(test.NoDBTestCase):
 
         self.assertTrue(configdrive.required_by(instance))
 
-    def test_config_flag_force(self):
+    def test_config_flag_force_for_new_vms(self):
         self.flags(force_config_drive=True)
 
         instance = objects.Instance(
             config_drive=None,
+            launched_at=None,
             system_metadata={
                 "image_img_config_drive": "optional",
             }
@@ -54,6 +55,19 @@ class ConfigDriveTestCase(test.NoDBTestCase):
 
         self.assertTrue(configdrive.required_by(instance))
 
+    def test_config_flag_force_for_existing_vms(self):
+        self.flags(force_config_drive=True)
+
+        instance = objects.Instance(
+            config_drive=None,
+            launched_at='2019-05-17T00:00:00.000000',
+            system_metadata={
+                "image_img_config_drive": "optional",
+            }
+        )
+
+        self.assertFalse(configdrive.required_by(instance))
+
     def test_no_config_drive(self):
         self.flags(force_config_drive=False)
 
diff --git a/nova/virt/configdrive.py b/nova/virt/configdrive.py
index 3e601ad436cc..7601872b25bc 100644
--- a/nova/virt/configdrive.py
+++ b/nova/virt/configdrive.py
@@ -160,8 +160,13 @@ def required_by(instance):
         "img_config_drive",
         fields.ConfigDrivePolicy.OPTIONAL)
 
+    # NOTE(pandatt): Option CONF.force_config_drive only applies to newly
+    # being-built VMs. And already launched VMs shouldn't be forced a config
+    # drive, because they may have been cloud-inited via metadata service, and
+    # do not need and have any config drive device. The `launched_at` property
+    # is an apparent flag to tell VMs being built from launched ones.
     return (instance.config_drive or
-            CONF.force_config_drive or
+            (CONF.force_config_drive and not instance.launched_at) or
             image_prop == fields.ConfigDrivePolicy.MANDATORY
             )