kunit: tool: refactor internal kconfig handling, allow overriding

Currently, you cannot ovewrwrite what's in your kunitconfig via
--kconfig_add.
Nor can you override something in a qemu_config via either means.

This patch makes it so we have this level of priority
* --kconfig_add
* kunitconfig file (the default or the one from --kunitconfig)
* qemu_config

The rationale for this order is that the more "dynamic" sources of
kconfig options should take priority.

--kconfig_add is obviously the most dynamic.
And for kunitconfig, users probably tweak the file manually or specify
--kunitconfig more often than they delve into qemu_config python files.

And internally, we convert the kconfigs from a python list into a set or
dict fairly often. We should just use a dict internally.
We exposed the set transform in the past since we didn't define __eq__,
so also take the chance to shore up the kunit_kconfig.Kconfig interface.

Example
=======

Let's consider the unrealistic example where someone would want to
disable CONFIG_KUNIT.
I.e. they run
$ ./tools/testing/kunit/kunit.py config --kconfig_add=CONFIG_KUNIT=n

Before
------
We'd write the following
> # CONFIG_KUNIT is not set
> CONFIG_KUNIT_ALL_TESTS=y
> CONFIG_KUNIT_TEST=y
> CONFIG_KUNIT=y
> CONFIG_KUNIT_EXAMPLE_TEST=y

And we'd error out with
> ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
> This is probably due to unsatisfied dependencies.
> Missing: # CONFIG_KUNIT is not set

After
-----
We'd write the following
> # CONFIG_KUNIT is not set
> CONFIG_KUNIT_TEST=y
> CONFIG_KUNIT_ALL_TESTS=y
> CONFIG_KUNIT_EXAMPLE_TEST=y

And we'd error out with
> ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
> This is probably due to unsatisfied dependencies.
> Missing: CONFIG_KUNIT_EXAMPLE_TEST=y, CONFIG_KUNIT_TEST=y, CONFIG_KUNIT_ALL_TESTS=y

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_kernel.py

@@ -53,8 +53,8 @@ class LinuxSourceTreeOperations:
 		except subprocess.CalledProcessError as e:
 			raise ConfigError(e.output.decode())
 
-	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> None:
-		pass
+	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> kunit_config.Kconfig:
+		return base_kunitconfig
 
 	def make_allyesconfig(self, build_dir: str, make_options) -> None:
 		raise ConfigError('Only the "um" arch is supported for alltests')
@@ -109,9 +109,10 @@ class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
 		self._kernel_command_line = qemu_arch_params.kernel_command_line + ' kunit_shutdown=reboot'
 		self._extra_qemu_params = qemu_arch_params.extra_qemu_params
 
-	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> None:
+	def make_arch_qemuconfig(self, base_kunitconfig: kunit_config.Kconfig) -> kunit_config.Kconfig:
 		kconfig = kunit_config.parse_from_string(self._kconfig)
-		base_kunitconfig.merge_in_entries(kconfig)
+		kconfig.merge_in_entries(base_kunitconfig)
+		return kconfig
 
 	def start(self, params: List[str], build_dir: str) -> subprocess.Popen:
 		kernel_path = os.path.join(build_dir, self._kernel_path)
@@ -268,10 +269,10 @@ class LinuxSourceTree:
 		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()
+		missing = set(self._kconfig.as_entries()) - set(validated_kconfig.as_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])
+			  'Missing: ' + ', '.join(str(e) for e in missing)
 		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".'
@@ -283,7 +284,7 @@ class LinuxSourceTree:
 		if build_dir and not os.path.exists(build_dir):
 			os.mkdir(build_dir)
 		try:
-			self._ops.make_arch_qemuconfig(self._kconfig)
+			self._kconfig = self._ops.make_arch_qemuconfig(self._kconfig)
 			self._kconfig.write_to_file(kconfig_path)
 			self._ops.make_olddefconfig(build_dir, make_options)
 		except ConfigError as e:
@@ -304,7 +305,7 @@ class LinuxSourceTree:
 			return True
 
 		old_kconfig = kunit_config.parse_file(old_path)
-		return old_kconfig.entries() != self._kconfig.entries()
+		return old_kconfig != self._kconfig
 
 	def build_reconfig(self, build_dir: str, make_options) -> bool:
 		"""Creates a new .config if it is not a subset of the .kunitconfig."""
@@ -314,7 +315,8 @@ class LinuxSourceTree:
 			return self.build_config(build_dir, make_options)
 
 		existing_kconfig = kunit_config.parse_file(kconfig_path)
-		self._ops.make_arch_qemuconfig(self._kconfig)
+		self._kconfig = 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 ...')