kunit: tool: introduce --qemu_args

Example usage:
$ ./tools/testing/kunit/kunit.py run --arch=x86_64 \
  --kconfig_add=CONFIG_SMP=y --qemu_args='-smp 8'

Looking in the test.log, one can see
> smp: Bringing up secondary CPUs ...
> .... node  #0, CPUs:      #1 #2 #3 #4 #5 #6 #7
> smp: Brought up 1 node, 8 CPUs

This flag would allow people to make tweaks like this without having to
create custom qemu_config files.

For consistency with --kernel_args, we allow users to repeat this
argument, e.g. you can tack on a --qemu_args='-m 2048', or you could
just append it to the first string ('-smp 8 -m 2048').

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

@@ -10,6 +10,7 @@
 import argparse
 import os
 import re
+import shlex
 import sys
 import time
 
@@ -324,6 +325,10 @@ def add_common_opts(parser) -> None:
 				  'a QemuArchParams object.'),
 			    type=str, metavar='FILE')
 
+	parser.add_argument('--qemu_args',
+			    help='Additional QEMU arguments, e.g. "-smp 8"',
+			    action='append', metavar='')
+
 def add_build_opts(parser) -> None:
 	parser.add_argument('--jobs',
 			    help='As in the make command, "Specifies  the number of '
@@ -369,12 +374,19 @@ def add_parse_opts(parser) -> None:
 
 def tree_from_args(cli_args: argparse.Namespace) -> kunit_kernel.LinuxSourceTree:
 	"""Returns a LinuxSourceTree based on the user's arguments."""
+	# Allow users to specify multiple arguments in one string, e.g. '-smp 8'
+	qemu_args: List[str] = []
+	if cli_args.qemu_args:
+		for arg in cli_args.qemu_args:
+			qemu_args.extend(shlex.split(arg))
+
 	return 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)
+			qemu_config_path=cli_args.qemu_config,
+			extra_qemu_args=qemu_args)
 
 
 def main(argv):

tools/testing/kunit/kunit_kernel.py

@@ -188,6 +188,7 @@ def _default_qemu_config_path(arch: str) -> str:
 	raise ConfigError(arch + ' is not a valid arch, options are ' + str(sorted(options)))
 
 def _get_qemu_ops(config_path: str,
+		  extra_qemu_args: Optional[List[str]],
 		  cross_compile: Optional[str]) -> Tuple[str, LinuxSourceTreeOperations]:
 	# The module name/path has very little to do with where the actual file
 	# exists (I learned this through experimentation and could not find it
@@ -208,6 +209,8 @@ def _get_qemu_ops(config_path: str,
 	if not hasattr(config, 'QEMU_ARCH'):
 		raise ValueError('qemu_config module missing "QEMU_ARCH": ' + config_path)
 	params: qemu_config.QemuArchParams = config.QEMU_ARCH  # type: ignore
+	if extra_qemu_args:
+		params.extra_qemu_params.extend(extra_qemu_args)
 	return params.linux_arch, LinuxSourceTreeOperationsQemu(
 			params, cross_compile=cross_compile)
 
@@ -221,17 +224,18 @@ class LinuxSourceTree:
 	      kconfig_add: Optional[List[str]]=None,
 	      arch=None,
 	      cross_compile=None,
-	      qemu_config_path=None) -> None:
+	      qemu_config_path=None,
+	      extra_qemu_args=None) -> None:
 		signal.signal(signal.SIGINT, self.signal_handler)
 		if qemu_config_path:
-			self._arch, self._ops = _get_qemu_ops(qemu_config_path, cross_compile)
+			self._arch, self._ops = _get_qemu_ops(qemu_config_path, extra_qemu_args, cross_compile)
 		else:
 			self._arch = 'um' if arch is None else arch
 			if self._arch == 'um':
 				self._ops = LinuxSourceTreeOperationsUml(cross_compile=cross_compile)
 			else:
 				qemu_config_path = _default_qemu_config_path(self._arch)
-				_, self._ops = _get_qemu_ops(qemu_config_path, cross_compile)
+				_, self._ops = _get_qemu_ops(qemu_config_path, extra_qemu_args, cross_compile)
 
 		if kunitconfig_path:
 			if os.path.isdir(kunitconfig_path):

tools/testing/kunit/kunit_tool_test.py

@@ -649,7 +649,8 @@ class KUnitMainTest(unittest.TestCase):
 						kconfig_add=None,
 						arch='um',
 						cross_compile=None,
-						qemu_config_path=None)
+						qemu_config_path=None,
+						extra_qemu_args=[])
 
 	def test_config_kunitconfig(self):
 		kunit.main(['config', '--kunitconfig=mykunitconfig'])
@@ -659,7 +660,8 @@ class KUnitMainTest(unittest.TestCase):
 						kconfig_add=None,
 						arch='um',
 						cross_compile=None,
-						qemu_config_path=None)
+						qemu_config_path=None,
+						extra_qemu_args=[])
 
 	def test_run_kconfig_add(self):
 		kunit.main(['run', '--kconfig_add=CONFIG_KASAN=y', '--kconfig_add=CONFIG_KCSAN=y'])
@@ -669,7 +671,19 @@ class KUnitMainTest(unittest.TestCase):
 						kconfig_add=['CONFIG_KASAN=y', 'CONFIG_KCSAN=y'],
 						arch='um',
 						cross_compile=None,
-						qemu_config_path=None)
+						qemu_config_path=None,
+						extra_qemu_args=[])
+
+	def test_run_qemu_args(self):
+		kunit.main(['run', '--arch=x86_64', '--qemu_args', '-m 2048'])
+		# Just verify that we parsed and initialized it correctly here.
+		self.mock_linux_init.assert_called_once_with('.kunit',
+						kunitconfig_path=None,
+						kconfig_add=None,
+						arch='x86_64',
+						cross_compile=None,
+						qemu_config_path=None,
+						extra_qemu_args=['-m', '2048'])
 
 	def test_run_kernel_args(self):
 		kunit.main(['run', '--kernel_args=a=1', '--kernel_args=b=2'])