diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
index cc5d844ecca1..d99ae75ef72f 100644
--- a/tools/testing/kunit/kunit_kernel.py
+++ b/tools/testing/kunit/kunit_kernel.py
@@ -93,6 +93,20 @@ class LinuxSourceTree(object):
 			return False
 		return True
 
+	def validate_config(self, build_dir):
+		kconfig_path = get_kconfig_path(build_dir)
+		validated_kconfig = kunit_config.Kconfig()
+		validated_kconfig.read_from_file(kconfig_path)
+		if not self._kconfig.is_subset_of(validated_kconfig):
+			invalid = self._kconfig.entries() - validated_kconfig.entries()
+			message = 'Provided Kconfig is not contained in validated .config. Following fields found in kunitconfig, ' \
+					  'but not in .config: %s' % (
+					', '.join([str(e) for e in invalid])
+			)
+			logging.error(message)
+			return False
+		return True
+
 	def build_config(self, build_dir):
 		kconfig_path = get_kconfig_path(build_dir)
 		if build_dir and not os.path.exists(build_dir):
@@ -103,12 +117,7 @@ class LinuxSourceTree(object):
 		except ConfigError as e:
 			logging.error(e)
 			return False
-		validated_kconfig = kunit_config.Kconfig()
-		validated_kconfig.read_from_file(kconfig_path)
-		if not self._kconfig.is_subset_of(validated_kconfig):
-			logging.error('Provided Kconfig is not contained in validated .config!')
-			return False
-		return True
+		return self.validate_config(build_dir)
 
 	def build_reconfig(self, build_dir):
 		"""Creates a new .config if it is not a subset of the .kunitconfig."""
@@ -133,12 +142,7 @@ class LinuxSourceTree(object):
 		except (ConfigError, BuildError) as e:
 			logging.error(e)
 			return False
-		used_kconfig = kunit_config.Kconfig()
-		used_kconfig.read_from_file(get_kconfig_path(build_dir))
-		if not self._kconfig.is_subset_of(used_kconfig):
-			logging.error('Provided Kconfig is not contained in final config!')
-			return False
-		return True
+		return self.validate_config(build_dir)
 
 	def run_kernel(self, args=[], timeout=None, build_dir=''):
 		args.extend(['mem=256M'])