kunit: tool: add --kconfig_add to allow easily tweaking kunitconfigs

E.g. run tests but with KASAN
$ ./tools/testing/kunit/kunit.py run --arch=x86_64 --kconfig_add=CONFIG_KASAN=y

This also works with --kunitconfig
$ ./tools/testing/kunit/kunit.py run --arch=x86_64 --kunitconfig=fs/ext4 --kconfig_add=CONFIG_KASAN=y

This flag is inspired by TuxMake's --kconfig-add, see
https://gitlab.com/Linaro/tuxmake#examples.

Our version just uses "_" as the delimiter for consistency with
pre-existing flags like --build_dir, --make_options, --kernel_args, etc.

Note: this does make it easier to run into a pre-existing edge case:
$ ./tools/testing/kunit/kunit.py run --arch=x86_64 --kconfig_add=CONFIG_KASAN=y
$ ./tools/testing/kunit/kunit.py run --arch=x86_64
This second invocation ^ still has KASAN enabled!

kunit.py won't call olddefconfig if our current .config is already a
superset of the provided kunitconfig.
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit.py

@@ -280,6 +280,10 @@ def add_common_opts(parser) -> None:
 			     ' If given a directory, (e.g. lib/kunit), "/.kunitconfig" '
 			     'will get  automatically appended.',
 			     metavar='kunitconfig')
+	parser.add_argument('--kconfig_add',
+			     help='Additional Kconfig options to append to the '
+			     '.kunitconfig, e.g. CONFIG_KASAN=y. Can be repeated.',
+			    action='append')
 
 	parser.add_argument('--arch',
 			    help=('Specifies the architecture to run tests under. '
@@ -398,6 +402,7 @@ def main(argv, linux=None):
 		if not linux:
 			linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
 					kunitconfig_path=cli_args.kunitconfig,
+					kconfig_add=cli_args.kconfig_add,
 					arch=cli_args.arch,
 					cross_compile=cli_args.cross_compile,
 					qemu_config_path=cli_args.qemu_config)
@@ -423,6 +428,7 @@ def main(argv, linux=None):
 		if not linux:
 			linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
 					kunitconfig_path=cli_args.kunitconfig,
+					kconfig_add=cli_args.kconfig_add,
 					arch=cli_args.arch,
 					cross_compile=cli_args.cross_compile,
 					qemu_config_path=cli_args.qemu_config)
@@ -439,6 +445,7 @@ def main(argv, linux=None):
 		if not linux:
 			linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
 					kunitconfig_path=cli_args.kunitconfig,
+					kconfig_add=cli_args.kconfig_add,
 					arch=cli_args.arch,
 					cross_compile=cli_args.cross_compile,
 					qemu_config_path=cli_args.qemu_config)
@@ -457,6 +464,7 @@ def main(argv, linux=None):
 		if not linux:
 			linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
 					kunitconfig_path=cli_args.kunitconfig,
+					kconfig_add=cli_args.kconfig_add,
 					arch=cli_args.arch,
 					cross_compile=cli_args.cross_compile,
 					qemu_config_path=cli_args.qemu_config)

tools/testing/kunit/kunit_kernel.py

@@ -224,6 +224,7 @@ class LinuxSourceTree(object):
 	      build_dir: str,
 	      load_config=True,
 	      kunitconfig_path='',
+	      kconfig_add: Optional[List[str]]=None,
 	      arch=None,
 	      cross_compile=None,
 	      qemu_config_path=None) -> None:
@@ -249,6 +250,10 @@ class LinuxSourceTree(object):
 				shutil.copyfile(DEFAULT_KUNITCONFIG_PATH, kunitconfig_path)
 
 		self._kconfig = kunit_config.parse_file(kunitconfig_path)
+		if kconfig_add:
+			kconfig = kunit_config.parse_from_string('\n'.join(kconfig_add))
+			self._kconfig.merge_in_entries(kconfig)
+
 
 	def clean(self) -> bool:
 		try:

tools/testing/kunit/kunit_tool_test.py

@@ -389,6 +389,10 @@ class LinuxSourceTreeTest(unittest.TestCase):
 				pass
 			kunit_kernel.LinuxSourceTree('', kunitconfig_path=dir)
 
+	def test_kconfig_add(self):
+		tree = kunit_kernel.LinuxSourceTree('', kconfig_add=['CONFIG_NOT_REAL=y'])
+		self.assertIn(kunit_config.KconfigEntry('NOT_REAL', 'y'), tree._kconfig.entries())
+
 	def test_invalid_arch(self):
 		with self.assertRaisesRegex(kunit_kernel.ConfigError, 'not a valid arch, options are.*x86_64'):
 			kunit_kernel.LinuxSourceTree('', arch='invalid')
@@ -601,6 +605,7 @@ class KUnitMainTest(unittest.TestCase):
 		# Just verify that we parsed and initialized it correctly here.
 		mock_linux_init.assert_called_once_with('.kunit',
 							kunitconfig_path='mykunitconfig',
+							kconfig_add=None,
 							arch='um',
 							cross_compile=None,
 							qemu_config_path=None)
@@ -612,6 +617,19 @@ class KUnitMainTest(unittest.TestCase):
 		# Just verify that we parsed and initialized it correctly here.
 		mock_linux_init.assert_called_once_with('.kunit',
 							kunitconfig_path='mykunitconfig',
+							kconfig_add=None,
+							arch='um',
+							cross_compile=None,
+							qemu_config_path=None)
+
+	@mock.patch.object(kunit_kernel, 'LinuxSourceTree')
+	def test_run_kconfig_add(self, mock_linux_init):
+		mock_linux_init.return_value = self.linux_source_mock
+		kunit.main(['run', '--kconfig_add=CONFIG_KASAN=y', '--kconfig_add=CONFIG_KCSAN=y'])
+		# Just verify that we parsed and initialized it correctly here.
+		mock_linux_init.assert_called_once_with('.kunit',
+							kunitconfig_path=None,
+							kconfig_add=['CONFIG_KASAN=y', 'CONFIG_KCSAN=y'],
 							arch='um',
 							cross_compile=None,
 							qemu_config_path=None)