Merge tag 'linux-kselftest-kunit-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull KUnit updates from Shuah Khan:
 "This consists of several fixes and enhancements. A few highlights:

   - Option --kconfig_add option allows easily tweaking kunitconfigs

   - make build subcommand can reconfigure if needed

   - doesn't error on tests without test plans

   - doesn't crash if no parameters are generated

   - defaults --jobs to # of cups

   - reports test parameter results as (K)TAP subtests"

* tag 'linux-kselftest-kunit-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  kunit: tool: Default --jobs to number of CPUs
  kunit: tool: fix newly introduced typechecker errors
  kunit: tool: make `build` subcommand also reconfigure if needed
  kunit: tool: delete kunit_parser.TestResult type
  kunit: tool: use dataclass instead of collections.namedtuple
  kunit: tool: suggest using decode_stacktrace.sh on kernel crash
  kunit: tool: reconfigure when the used kunitconfig changes
  kunit: tool: revamp message for invalid kunitconfig
  kunit: tool: add --kconfig_add to allow easily tweaking kunitconfigs
  kunit: tool: move Kconfig read_from_file/parse_from_string to package-level
  kunit: tool: print parsed test results fully incrementally
  kunit: Report test parameter results as (K)TAP subtests
  kunit: Don't crash if no parameters are generated
  kunit: tool: Report an error if any test has no subtests
  kunit: tool: Do not error on tests without test plans
  kunit: add run_checks.py script to validate kunit changes
  Documentation: kunit: remove claims that kunit is a mocking framework
  kunit: tool: fix --json output for skipped tests

13 files changed, 480 insertions, 204 deletions

diff --git a/Documentation/dev-tools/kunit/api/index.rst b/Documentation/dev-tools/kunit/api/index.rst
index b33ad72bcf0b..3006cadcf44a 100644
--- a/Documentation/dev-tools/kunit/api/index.rst
+++ b/Documentation/dev-tools/kunit/api/index.rst
@@ -12,5 +12,4 @@ following sections:
 
 Documentation/dev-tools/kunit/api/test.rst
 
- - documents all of the standard testing API excluding mocking
-   or mocking related features.
+ - documents all of the standard testing API
diff --git a/Documentation/dev-tools/kunit/api/test.rst b/Documentation/dev-tools/kunit/api/test.rst
index aaa97f17e5b3..c5eca423e8b6 100644
--- a/Documentation/dev-tools/kunit/api/test.rst
+++ b/Documentation/dev-tools/kunit/api/test.rst
@@ -4,8 +4,7 @@
 Test API
 ========
 
-This file documents all of the standard testing API excluding mocking or mocking
-related features.
+This file documents all of the standard testing API.
 
 .. kernel-doc:: include/kunit/test.h
    :internal:
diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst
index cacb35ec658d..7af7dec83646 100644
--- a/Documentation/dev-tools/kunit/index.rst
+++ b/Documentation/dev-tools/kunit/index.rst
@@ -19,7 +19,7 @@ KUnit - Unit Testing for the Linux Kernel
 What is KUnit?
 ==============
 
-KUnit is a lightweight unit testing and mocking framework for the Linux kernel.
+KUnit is a lightweight unit testing framework for the Linux kernel.
 
 KUnit is heavily inspired by JUnit, Python's unittest.mock, and
 Googletest/Googlemock for C++. KUnit provides facilities for defining unit test
diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst
index 1e00f9226f74..0a5e65540974 100644
--- a/Documentation/dev-tools/kunit/start.rst
+++ b/Documentation/dev-tools/kunit/start.rst
@@ -50,10 +50,10 @@ It'll warn you if you haven't included the dependencies of the options you're
 using.
 
 .. note::
-   Note that removing something from the ``.kunitconfig`` will not trigger a
-   rebuild of the ``.config`` file: the configuration is only updated if the
-   ``.kunitconfig`` is not a subset of ``.config``. This means that you can use
-   other tools (such as make menuconfig) to adjust other config options.
+   If you change the ``.kunitconfig``, kunit.py will trigger a rebuild of the
+   ``.config`` file. But you can edit the ``.config`` file directly or with
+   tools like ``make menuconfig O=.kunit``. As long as its a superset of
+   ``.kunitconfig``, kunit.py won't overwrite your changes.
 
 
 Running the tests (KUnit Wrapper)
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 3bd741e50a2d..c7ed4aabec04 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -504,25 +504,28 @@ int kunit_run_tests(struct kunit_suite *suite)
 		struct kunit_result_stats param_stats = { 0 };
 		test_case->status = KUNIT_SKIPPED;
 
-		if (test_case->generate_params) {
+		if (!test_case->generate_params) {
+			/* Non-parameterised test. */
+			kunit_run_case_catch_errors(suite, test_case, &test);
+			kunit_update_stats(&param_stats, test.status);
+		} else {
 			/* Get initial param. */
 			param_desc[0] = '\0';
 			test.param_value = test_case->generate_params(NULL, param_desc);
-		}
+			kunit_log(KERN_INFO, &test, KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
+				  "# Subtest: %s", test_case->name);
 
-		do {
-			kunit_run_case_catch_errors(suite, test_case, &test);
+			while (test.param_value) {
+				kunit_run_case_catch_errors(suite, test_case, &test);
 
-			if (test_case->generate_params) {
 				if (param_desc[0] == '\0') {
 					snprintf(param_desc, sizeof(param_desc),
 						 "param-%d", test.param_index);
 				}
 
 				kunit_log(KERN_INFO, &test,
-					  KUNIT_SUBTEST_INDENT
-					  "# %s: %s %d - %s",
-					  test_case->name,
+					  KUNIT_SUBTEST_INDENT KUNIT_SUBTEST_INDENT
+					  "%s %d - %s",
 					  kunit_status_to_ok_not_ok(test.status),
 					  test.param_index + 1, param_desc);
 
@@ -530,11 +533,11 @@ int kunit_run_tests(struct kunit_suite *suite)
 				param_desc[0] = '\0';
 				test.param_value = test_case->generate_params(test.param_value, param_desc);
 				test.param_index++;
-			}
 
-			kunit_update_stats(&param_stats, test.status);
+				kunit_update_stats(&param_stats, test.status);
+			}
+		}
 
-		} while (test.param_value);
 
 		kunit_print_test_stats(&test, param_stats);
 
diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
index 68e6f461c758..7a706f96f68d 100755
--- a/tools/testing/kunit/kunit.py
+++ b/tools/testing/kunit/kunit.py
@@ -15,38 +15,57 @@ import time
 
 assert sys.version_info >= (3, 7), "Python version is too old"
 
-from collections import namedtuple
+from dataclasses import dataclass
 from enum import Enum, auto
-from typing import Iterable, Sequence, List
+from typing import Any, Iterable, Sequence, List, Optional
 
 import kunit_json
 import kunit_kernel
 import kunit_parser
 
-KunitResult = namedtuple('KunitResult', ['status','result','elapsed_time'])
-
-KunitConfigRequest = namedtuple('KunitConfigRequest',
-				['build_dir', 'make_options'])
-KunitBuildRequest = namedtuple('KunitBuildRequest',
-			       ['jobs', 'build_dir', 'alltests',
-				'make_options'])
-KunitExecRequest = namedtuple('KunitExecRequest',
-			      ['timeout', 'build_dir', 'alltests',
-			       'filter_glob', 'kernel_args', 'run_isolated'])
-KunitParseRequest = namedtuple('KunitParseRequest',
-			       ['raw_output', 'build_dir', 'json'])
-KunitRequest = namedtuple('KunitRequest', ['raw_output','timeout', 'jobs',
-					   'build_dir', 'alltests', 'filter_glob',
-					   'kernel_args', 'run_isolated', 'json', 'make_options'])
-
-KernelDirectoryPath = sys.argv[0].split('tools/testing/kunit/')[0]
-
 class KunitStatus(Enum):
 	SUCCESS = auto()
 	CONFIG_FAILURE = auto()
 	BUILD_FAILURE = auto()
 	TEST_FAILURE = auto()
 
+@dataclass
+class KunitResult:
+	status: KunitStatus
+	result: Any
+	elapsed_time: float
+
+@dataclass
+class KunitConfigRequest:
+	build_dir: str
+	make_options: Optional[List[str]]
+
+@dataclass
+class KunitBuildRequest(KunitConfigRequest):
+	jobs: int
+	alltests: bool
+
+@dataclass
+class KunitParseRequest:
+	raw_output: Optional[str]
+	build_dir: str
+	json: Optional[str]
+
+@dataclass
+class KunitExecRequest(KunitParseRequest):
+	timeout: int
+	alltests: bool
+	filter_glob: str
+	kernel_args: Optional[List[str]]
+	run_isolated: Optional[str]
+
+@dataclass
+class KunitRequest(KunitExecRequest, KunitBuildRequest):
+	pass
+
+
+KernelDirectoryPath = sys.argv[0].split('tools/testing/kunit/')[0]
+
 def get_kernel_root_path() -> str:
 	path = sys.argv[0] if not __file__ else __file__
 	parts = os.path.realpath(path).split('tools/testing/kunit')
@@ -91,6 +110,14 @@ def build_tests(linux: kunit_kernel.LinuxSourceTree,
 			   'built kernel successfully',
 			   build_end - build_start)
 
+def config_and_build_tests(linux: kunit_kernel.LinuxSourceTree,
+			   request: KunitBuildRequest) -> KunitResult:
+	config_result = config_tests(linux, request)
+	if config_result.status != KunitStatus.SUCCESS:
+		return config_result
+
+	return build_tests(linux, request)
+
 def _list_tests(linux: kunit_kernel.LinuxSourceTree, request: KunitExecRequest) -> List[str]:
 	args = ['kunit.action=list']
 	if request.kernel_args:
@@ -121,8 +148,7 @@ def _suites_from_test_list(tests: List[str]) -> List[str]:
 
 
 
-def exec_tests(linux: kunit_kernel.LinuxSourceTree, request: KunitExecRequest,
-	       parse_request: KunitParseRequest) -> KunitResult:
+def exec_tests(linux: kunit_kernel.LinuxSourceTree, request: KunitExecRequest) -> KunitResult:
 	filter_globs = [request.filter_glob]
 	if request.run_isolated:
 		tests = _list_tests(linux, request)
@@ -147,17 +173,23 @@ def exec_tests(linux: kunit_kernel.LinuxSourceTree, request: KunitExecRequest,
 			filter_glob=filter_glob,
 			build_dir=request.build_dir)
 
-		result = parse_tests(parse_request, run_result)
+		result = parse_tests(request, run_result)
 		# run_kernel() doesn't block on the kernel exiting.
 		# That only happens after we get the last line of output from `run_result`.
 		# So exec_time here actually contains parsing + execution time, which is fine.
 		test_end = time.time()
 		exec_time += test_end - test_start
 
-		test_counts.add_subtest_counts(result.result.test.counts)
+		test_counts.add_subtest_counts(result.result.counts)
+
+	if len(filter_globs) == 1 and test_counts.crashed > 0:
+		bd = request.build_dir
+		print('The kernel seems to have crashed; you can decode the stack traces with:')
+		print('$ scripts/decode_stacktrace.sh {}/vmlinux {} < {} | tee {}/decoded.log | {} parse'.format(
+				bd, bd, kunit_kernel.get_outfile_path(bd), bd, sys.argv[0]))
 
 	kunit_status = _map_to_overall_status(test_counts.get_status())
-	return KunitResult(status=kunit_status, result=result.result, elapsed_time=exec_time)
+	return KunitResult(status=kunit_status, result=result, elapsed_time=exec_time)
 
 def _map_to_overall_status(test_status: kunit_parser.TestStatus) -> KunitStatus:
 	if test_status in (kunit_parser.TestStatus.SUCCESS, kunit_parser.TestStatus.SKIPPED):
@@ -168,14 +200,12 @@ def _map_to_overall_status(test_status: kunit_parser.TestStatus) -> KunitStatus:
 def parse_tests(request: KunitParseRequest, input_data: Iterable[str]) -> KunitResult:
 	parse_start = time.time()
 
-	test_result = kunit_parser.TestResult(kunit_parser.TestStatus.SUCCESS,
-					      kunit_parser.Test(),
-					      'Tests not Parsed.')
+	test_result = kunit_parser.Test()
 
 	if request.raw_output:
 		# Treat unparsed results as one passing test.
-		test_result.test.status = kunit_parser.TestStatus.SUCCESS
-		test_result.test.counts.passed = 1
+		test_result.status = kunit_parser.TestStatus.SUCCESS
+		test_result.counts.passed = 1
 
 		output: Iterable[str] = input_data
 		if request.raw_output == 'all':
@@ -193,7 +223,7 @@ def parse_tests(request: KunitParseRequest, input_data: Iterable[str]) -> KunitR
 
 	if request.json:
 		json_obj = kunit_json.get_json_result(
-					test_result=test_result,
+					test=test_result,
 					def_config='kunit_defconfig',
 					build_dir=request.build_dir,
 					json_path=request.json)
@@ -211,27 +241,15 @@ def run_tests(linux: kunit_kernel.LinuxSourceTree,
 	      request: KunitRequest) -> KunitResult:
 	run_start = time.time()
 
-	config_request = KunitConfigRequest(request.build_dir,
-					    request.make_options)
-	config_result = config_tests(linux, config_request)
+	config_result = config_tests(linux, request)
 	if config_result.status != KunitStatus.SUCCESS:
 		return config_result
 
-	build_request = KunitBuildRequest(request.jobs, request.build_dir,
-					  request.alltests,
-					  request.make_options)
-	build_result = build_tests(linux, build_request)
+	build_result = build_tests(linux, request)
 	if build_result.status != KunitStatus.SUCCESS:
 		return build_result
 
-	exec_request = KunitExecRequest(request.timeout, request.build_dir,
-				 request.alltests, request.filter_glob,
-				 request.kernel_args, request.run_isolated)
-	parse_request = KunitParseRequest(request.raw_output,
-					  request.build_dir,
-					  request.json)
-
-	exec_result = exec_tests(linux, exec_request, parse_request)
+	exec_result = exec_tests(linux, request)
 
 	run_end = time.time()
 
@@ -264,6 +282,9 @@ def massage_argv(argv: Sequence[str]) -> Sequence[str]:
 		return  f'{arg}={pseudo_bool_flag_defaults[arg]}'
 	return list(map(massage_arg, argv))
 
+def get_default_jobs() -> int:
+	return len(os.sched_getaffinity(0))
+
 def add_common_opts(parser) -> None:
 	parser.add_argument('--build_dir',
 			    help='As in the make command, it specifies the build '
@@ -280,6 +301,10 @@ 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. '
@@ -310,7 +335,7 @@ def add_build_opts(parser) -> None:
 	parser.add_argument('--jobs',
 			    help='As in the make command, "Specifies  the number of '
 			    'jobs (commands) to run simultaneously."',
-			    type=int, default=8, metavar='jobs')
+			    type=int, default=get_default_jobs(), metavar='jobs')
 
 def add_exec_opts(parser) -> None:
 	parser.add_argument('--timeout',
@@ -398,20 +423,21 @@ 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)
 
-		request = KunitRequest(cli_args.raw_output,
-				       cli_args.timeout,
-				       cli_args.jobs,
-				       cli_args.build_dir,
-				       cli_args.alltests,
-				       cli_args.filter_glob,
-				       cli_args.kernel_args,
-				       cli_args.run_isolated,
-				       cli_args.json,
-				       cli_args.make_options)
+		request = KunitRequest(build_dir=cli_args.build_dir,
+				       make_options=cli_args.make_options,
+				       jobs=cli_args.jobs,
+				       alltests=cli_args.alltests,
+				       raw_output=cli_args.raw_output,
+				       json=cli_args.json,
+				       timeout=cli_args.timeout,
+				       filter_glob=cli_args.filter_glob,
+				       kernel_args=cli_args.kernel_args,
+				       run_isolated=cli_args.run_isolated)
 		result = run_tests(linux, request)
 		if result.status != KunitStatus.SUCCESS:
 			sys.exit(1)
@@ -423,12 +449,13 @@ 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)
 
-		request = KunitConfigRequest(cli_args.build_dir,
-					     cli_args.make_options)
+		request = KunitConfigRequest(build_dir=cli_args.build_dir,
+					     make_options=cli_args.make_options)
 		result = config_tests(linux, request)
 		kunit_parser.print_with_timestamp((
 			'Elapsed time: %.3fs\n') % (
@@ -439,15 +466,16 @@ 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)
 
-		request = KunitBuildRequest(cli_args.jobs,
-					    cli_args.build_dir,
-					    cli_args.alltests,
-					    cli_args.make_options)
-		result = build_tests(linux, request)
+		request = KunitBuildRequest(build_dir=cli_args.build_dir,
+					    make_options=cli_args.make_options,
+					    jobs=cli_args.jobs,
+					    alltests=cli_args.alltests)
+		result = config_and_build_tests(linux, request)
 		kunit_parser.print_with_timestamp((
 			'Elapsed time: %.3fs\n') % (
 				result.elapsed_time))
@@ -457,20 +485,20 @@ 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)
 
-		exec_request = KunitExecRequest(cli_args.timeout,
-						cli_args.build_dir,
-						cli_args.alltests,
-						cli_args.filter_glob,
-						cli_args.kernel_args,
-						cli_args.run_isolated)
-		parse_request = KunitParseRequest(cli_args.raw_output,
-						  cli_args.build_dir,
-						  cli_args.json)
-		result = exec_tests(linux, exec_request, parse_request)
+		exec_request = KunitExecRequest(raw_output=cli_args.raw_output,
+						build_dir=cli_args.build_dir,
+						json=cli_args.json,
+						timeout=cli_args.timeout,
+						alltests=cli_args.alltests,
+						filter_glob=cli_args.filter_glob,
+						kernel_args=cli_args.kernel_args,
+						run_isolated=cli_args.run_isolated)
+		result = exec_tests(linux, exec_request)
 		kunit_parser.print_with_timestamp((
 			'Elapsed time: %.3fs\n') % (result.elapsed_time))
 		if result.status != KunitStatus.SUCCESS:
@@ -482,9 +510,9 @@ def main(argv, linux=None):
 		else:
 			with open(cli_args.file, 'r', errors='backslashreplace') as f:
 				kunit_output = f.read().splitlines()
-		request = KunitParseRequest(cli_args.raw_output,
-					    None,
-					    cli_args.json)
+		request = KunitParseRequest(raw_output=cli_args.raw_output,
+					    build_dir='',
+					    json=cli_args.json)
 		result = parse_tests(request, kunit_output)
 		if result.status != KunitStatus.SUCCESS:
 			sys.exit(1)
diff --git a/tools/testing/kunit/kunit_config.py b/tools/testing/kunit/kunit_config.py
index c77c7d2ef622..677354546156 100644
--- a/tools/testing/kunit/kunit_config.py
+++ b/tools/testing/kunit/kunit_config.py
@@ -62,33 +62,34 @@ class Kconfig(object):
 			for entry in self.entries():
 				f.write(str(entry) + '\n')
 
-	def parse_from_string(self, blob: str) -> None:
-		"""Parses a string containing KconfigEntrys and populates this Kconfig."""
-		self._entries = []
-		is_not_set_matcher = re.compile(CONFIG_IS_NOT_SET_PATTERN)
-		config_matcher = re.compile(CONFIG_PATTERN)
-		for line in blob.split('\n'):
-			line = line.strip()
-			if not line:
-				continue
-
-			match = config_matcher.match(line)
-			if match:
-				entry = KconfigEntry(match.group(1), match.group(2))
-				self.add_entry(entry)
-				continue
-
-			empty_match = is_not_set_matcher.match(line)
-			if empty_match:
-				entry = KconfigEntry(empty_match.group(1), 'n')
-				self.add_entry(entry)
-				continue
-
-			if line[0] == '#':
-				continue
-			else:
-				raise KconfigParseError('Failed to parse: ' + line)
-
-	def read_from_file(self, path: str) -> None:
-		with open(path, 'r') as f:
-			self.parse_from_string(f.read())
+def parse_file(path: str) -> Kconfig:
+	with open(path, 'r') as f:
+		return parse_from_string(f.read())
+
+def parse_from_string(blob: str) -> Kconfig:
+	"""Parses a string containing Kconfig entries."""
+	kconfig = Kconfig()
+	is_not_set_matcher = re.compile(CONFIG_IS_NOT_SET_PATTERN)
+	config_matcher = re.compile(CONFIG_PATTERN)
+	for line in blob.split('\n'):
+		line = line.strip()
+		if not line:
+			continue
+
+		match = config_matcher.match(line)
+		if match:
+			entry = KconfigEntry(match.group(1), match.group(2))
+			kconfig.add_entry(entry)
+			continue
+
+		empty_match = is_not_set_matcher.match(line)
+		if empty_match:
+			entry = KconfigEntry(empty_match.group(1), 'n')
+			kconfig.add_entry(entry)
+			continue
+
+		if line[0] == '#':
+			continue
+		else:
+			raise KconfigParseError('Failed to parse: ' + line)
+	return kconfig
diff --git a/tools/testing/kunit/kunit_json.py b/tools/testing/kunit/kunit_json.py
index 746bec72b9ac..6862671709bc 100644
--- a/tools/testing/kunit/kunit_json.py
+++ b/tools/testing/kunit/kunit_json.py
@@ -11,7 +11,7 @@ import os
 
 import kunit_parser
 
-from kunit_parser import Test, TestResult, TestStatus
+from kunit_parser import Test, TestStatus
 from typing import Any, Dict, Optional
 
 JsonObj = Dict[str, Any]
@@ -30,6 +30,8 @@ def _get_group_json(test: Test, def_config: str,
 			test_case = {"name": subtest.name, "status": "FAIL"}
 			if subtest.status == TestStatus.SUCCESS:
 				test_case["status"] = "PASS"
+			elif subtest.status == TestStatus.SKIPPED:
+				test_case["status"] = "SKIP"
 			elif subtest.status == TestStatus.TEST_CRASHED:
 				test_case["status"] = "ERROR"
 			test_cases.append(test_case)
@@ -48,9 +50,9 @@ def _get_group_json(test: Test, def_config: str,
 	}
 	return test_group
 
-def get_json_result(test_result: TestResult, def_config: str,
+def get_json_result(test: Test, def_config: str,
 		build_dir: Optional[str], json_path: str) -> str:
-	test_group = _get_group_json(test_result.test, def_config, build_dir)
+	test_group = _get_group_json(test, def_config, build_dir)
 	test_group["name"] = "KUnit Test Group"
 	json_obj = json.dumps(test_group, indent=4)
 	if json_path != 'stdout':
diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
index 66095568bf32..44bbe54f25f1 100644
--- a/tools/testing/kunit/kunit_kernel.py
+++ b/tools/testing/kunit/kunit_kernel.py
@@ -21,6 +21,7 @@ import qemu_config
 
 KCONFIG_PATH = '.config'
 KUNITCONFIG_PATH = '.kunitconfig'
+OLD_KUNITCONFIG_PATH = 'last_used_kunitconfig'
 DEFAULT_KUNITCONFIG_PATH = 'tools/testing/kunit/configs/default.config'
 BROKEN_ALLCONFIG_PATH = 'tools/testing/kunit/configs/broken_on_uml.config'
 OUTFILE_PATH = 'test.log'
@@ -116,8 +117,7 @@ class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
 		self._extra_qemu_params = qemu_arch_params.extra_qemu_params
 
 	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> None:
-		kconfig = kunit_config.Kconfig()
-		kconfig.parse_from_string(self._kconfig)
+		kconfig = kunit_config.parse_from_string(self._kconfig)
 		base_kunitconfig.merge_in_entries(kconfig)
 
 	def start(self, params: List[str], build_dir: str) -> subprocess.Popen:
@@ -180,6 +180,9 @@ def get_kconfig_path(build_dir) -> str:
 def get_kunitconfig_path(build_dir) -> str:
 	return get_file_path(build_dir, KUNITCONFIG_PATH)
 
+def get_old_kunitconfig_path(build_dir) -> str:
+	return get_file_path(build_dir, OLD_KUNITCONFIG_PATH)
+
 def get_outfile_path(build_dir) -> str:
 	return get_file_path(build_dir, OUTFILE_PATH)
 
@@ -206,6 +209,7 @@ def get_source_tree_ops_from_qemu_config(config_path: str,
 	# exists as a file.
 	module_path = '.' + os.path.join(os.path.basename(QEMU_CONFIGS_DIR), os.path.basename(config_path))
 	spec = importlib.util.spec_from_file_location(module_path, config_path)
+	assert spec is not None
 	config = importlib.util.module_from_spec(spec)
 	# See https://github.com/python/typeshed/pull/2626 for context.
 	assert isinstance(spec.loader, importlib.abc.Loader)
@@ -225,6 +229,7 @@ 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:
@@ -249,8 +254,11 @@ class LinuxSourceTree(object):
 			if not os.path.exists(kunitconfig_path):
 				shutil.copyfile(DEFAULT_KUNITCONFIG_PATH, kunitconfig_path)
 
-		self._kconfig = kunit_config.Kconfig()
-		self._kconfig.read_from_file(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:
@@ -262,17 +270,18 @@ class LinuxSourceTree(object):
 
 	def validate_config(self, build_dir) -> bool:
 		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
+		validated_kconfig = kunit_config.parse_file(kconfig_path)
+		if self._kconfig.is_subset_of(validated_kconfig):
+			return True
+		invalid = self._kconfig.entries() - validated_kconfig.entries()
+		message = 'Not all Kconfig options selected in kunitconfig were in the generated .config.\n' \
+			  'This is probably due to unsatisfied dependencies.\n' \
+			  'Missing: ' + ', '.join([str(e) for e in invalid])
+		if self._arch == 'um':
+			message += '\nNote: many Kconfig options aren\'t available on UML. You can try running ' \
+				   'on a different architecture with something like "--arch=x86_64".'
+		logging.error(message)
+		return False
 
 	def build_config(self, build_dir, make_options) -> bool:
 		kconfig_path = get_kconfig_path(build_dir)
@@ -285,25 +294,38 @@ class LinuxSourceTree(object):
 		except ConfigError as e:
 			logging.error(e)
 			return False
-		return self.validate_config(build_dir)
+		if not self.validate_config(build_dir):
+			return False
+
+		old_path = get_old_kunitconfig_path(build_dir)
+		if os.path.exists(old_path):
+			os.remove(old_path)  # write_to_file appends to the file
+		self._kconfig.write_to_file(old_path)
+		return True
+
+	def _kunitconfig_changed(self, build_dir: str) -> bool:
+		old_path = get_old_kunitconfig_path(build_dir)
+		if not os.path.exists(old_path):
+			return True
+
+		old_kconfig = kunit_config.parse_file(old_path)
+		return old_kconfig.entries() != self._kconfig.entries()
 
 	def build_reconfig(self, build_dir, make_options) -> bool:
 		"""Creates a new .config if it is not a subset of the .kunitconfig."""
 		kconfig_path = get_kconfig_path(build_dir)
-		if os.path.exists(kconfig_path):
-			existing_kconfig = kunit_config.Kconfig()
-			existing_kconfig.read_from_file(kconfig_path)
-			self._ops.make_arch_qemuconfig(self._kconfig)
-			if not self._kconfig.is_subset_of(existing_kconfig):
-				print('Regenerating .config ...')
-				os.remove(kconfig_path)
-				return self.build_config(build_dir, make_options)
-			else:
-				return True
-		else:
+		if not os.path.exists(kconfig_path):
 			print('Generating .config ...')
 			return self.build_config(build_dir, make_options)
 
+		existing_kconfig = kunit_config.parse_file(kconfig_path)
+		self._ops.make_arch_qemuconfig(self._kconfig)
+		if self._kconfig.is_subset_of(existing_kconfig) and not self._kunitconfig_changed(build_dir):
+			return True
+		print('Regenerating .config ...')
+		os.remove(kconfig_path)
+		return self.build_config(build_dir, make_options)
+
 	def build_kernel(self, alltests, jobs, build_dir, make_options) -> bool:
 		try:
 			if alltests:
diff --git a/tools/testing/kunit/kunit_parser.py b/tools/testing/kunit/kunit_parser.py
index 3355196d0515..05ff334761dd 100644
--- a/tools/testing/kunit/kunit_parser.py
+++ b/tools/testing/kunit/kunit_parser.py
@@ -12,14 +12,11 @@
 from __future__ import annotations
 import re
 
-from collections import namedtuple
-from datetime import datetime
+import datetime
 from enum import Enum, auto
 from functools import reduce
 from typing import Iterable, Iterator, List, Optional, Tuple
 
-TestResult = namedtuple('TestResult', ['status','test','log'])
-
 class Test(object):
 	"""
 	A class to represent a test parsed from KTAP results. All KTAP
@@ -168,42 +165,51 @@ class TestCounts:
 class LineStream:
 	"""
 	A class to represent the lines of kernel output.
-	Provides a peek()/pop() interface over an iterator of
+	Provides a lazy peek()/pop() interface over an iterator of
 	(line#, text).
 	"""
 	_lines: Iterator[Tuple[int, str]]
 	_next: Tuple[int, str]
+	_need_next: bool
 	_done: bool
 
 	def __init__(self, lines: Iterator[Tuple[int, str]]):
 		"""Creates a new LineStream that wraps the given iterator."""
 		self._lines = lines
 		self._done = False
+		self._need_next = True
 		self._next = (0, '')
-		self._get_next()
 
 	def _get_next(self) -> None:
-		"""Advances the LineSteam to the next line."""
+		"""Advances the LineSteam to the next line, if necessary."""
+		if not self._need_next:
+			return
 		try:
 			self._next = next(self._lines)
 		except StopIteration:
 			self._done = True
+		finally:
+			self._need_next = False
 
 	def peek(self) -> str:
 		"""Returns the current line, without advancing the LineStream.
 		"""
+		self._get_next()
 		return self._next[1]
 
 	def pop(self) -> str:
 		"""Returns the current line and advances the LineStream to
 		the next line.
 		"""
-		n = self._next
-		self._get_next()
-		return n[1]
+		s = self.peek()
+		if self._done:
+			raise ValueError(f'LineStream: going past EOF, last line was {s}')
+		self._need_next = True
+		return s
 
 	def __bool__(self) -> bool:
 		"""Returns True if stream has more lines."""
+		self._get_next()
 		return not self._done
 
 	# Only used by kunit_tool_test.py.
@@ -216,6 +222,7 @@ class LineStream:
 
 	def line_number(self) -> int:
 		"""Returns the line number of the current line."""
+		self._get_next()
 		return self._next[0]
 
 # Parsing helper methods:
@@ -340,8 +347,8 @@ def parse_test_plan(lines: LineStream, test: Test) -> bool:
 	"""
 	Parses test plan line and stores the expected number of subtests in
 	test object. Reports an error if expected count is 0.
-	Returns False and reports missing test plan error if fails to parse
-	test plan.
+	Returns False and sets expected_count to None if there is no valid test
+	plan.
 
 	Accepted format:
 	- '1..[number of subtests]'
@@ -356,14 +363,10 @@ def parse_test_plan(lines: LineStream, test: Test) -> bool:
 	match = TEST_PLAN.match(lines.peek())
 	if not match:
 		test.expected_count = None
-		test.add_error('missing plan line!')
 		return False
 	test.log.append(lines.pop())
 	expected_count = int(match.group(1))
 	test.expected_count = expected_count
-	if expected_count == 0:
-		test.status = TestStatus.NO_TESTS
-		test.add_error('0 tests run!')
 	return True
 
 TEST_RESULT = re.compile(r'^(ok|not ok) ([0-9]+) (- )?([^#]*)( # .*)?$')
@@ -514,7 +517,7 @@ ANSI_LEN = len(red(''))
 
 def print_with_timestamp(message: str) -> None:
 	"""Prints message with timestamp at beginning."""
-	print('[%s] %s' % (datetime.now().strftime('%H:%M:%S'), message))
+	print('[%s] %s' % (datetime.datetime.now().strftime('%H:%M:%S'), message))
 
 def format_test_divider(message: str, len_message: int) -> str:
 	"""
@@ -590,6 +593,8 @@ def format_test_result(test: Test) -> str:
 		return (green('[PASSED] ') + test.name)
 	elif test.status == TestStatus.SKIPPED:
 		return (yellow('[SKIPPED] ') + test.name)
+	elif test.status == TestStatus.NO_TESTS:
+		return (yellow('[NO TESTS RUN] ') + test.name)
 	elif test.status == TestStatus.TEST_CRASHED:
 		print_log(test.log)
 		return (red('[CRASHED] ') + test.name)
@@ -732,6 +737,7 @@ def parse_test(lines: LineStream, expected_num: int, log: List[str]) -> Test:
 		# test plan
 		test.name = "main"
 		parse_test_plan(lines, test)
+		parent_test = True
 	else:
 		# If KTAP/TAP header is not found, test must be subtest
 		# header or test result line so parse attempt to parser
@@ -745,7 +751,7 @@ def parse_test(lines: LineStream, expected_num: int, log: List[str]) -> Test:
 	expected_count = test.expected_count
 	subtests = []
 	test_num = 1
-	while expected_count is None or test_num <= expected_count:
+	while parent_test and (expected_count is None or test_num <= expected_count):
 		# Loop to parse any subtests.