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Date:   Tue, 4 May 2021 13:07:48 -0700
From:   Brendan Higgins <brendanhiggins@google.com>
To:     David Gow <davidgow@google.com>
Cc:     Shuah Khan <shuah@kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        KUnit Development <kunit-dev@googlegroups.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Daniel Latypov <dlatypov@google.com>
Subject: Re: [RFC v2 3/4] kunit: tool: add support for QEMU
Message-ID: <YJGplIw5COtzKqso@google.com>
References: <20210429205109.2847831-1-brendanhiggins@google.com>
 <20210429205109.2847831-4-brendanhiggins@google.com>
 <CABVgOSnrSD64aTRsBqTTB4A26whcxegT0_DK3MjThsHnWeFdqA@mail.gmail.com>
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On Tue, May 04, 2021 at 02:08:41PM +0800, David Gow wrote:
> On Fri, Apr 30, 2021 at 4:51 AM Brendan Higgins
> <brendanhiggins@google.com> wrote:
> >
> > Add basic support to run QEMU via kunit_tool. Add support for i386,
> > x86_64, arm, arm64, and a bunch more.
> >
> > Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
> 
> I've tested this out on a few architectures (x86-32, ppc64, etc), and
> it all seems to work pretty well. I've got quite a few comments below.
> The main one -- the location of the qemu configs -- is basically
> echoing what Daniel said and what you've done on the Gerrit version,
> but I felt was worth having on the record.
> 
> Otherwise, a bunch of nitpicks around missing places cross_compile
> should be supported.
> 
> Still, great to see this happening: it's nice to be able to test on
> non-UML architectures more easily.
> 
> Tested-by: David Gow <davidgow@google.com>

Sweet, thanks!

> -- David
> 
> > ---
> >  tools/testing/kunit/kunit.py           |  33 +++-
> >  tools/testing/kunit/kunit_config.py    |   2 +-
> >  tools/testing/kunit/kunit_kernel.py    | 207 +++++++++++++++++++++----
> >  tools/testing/kunit/kunit_tool_test.py |  15 +-
> >  4 files changed, 217 insertions(+), 40 deletions(-)
> >
> > diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
> > index d5144fcb03acd..07ef80062873b 100755
> > --- a/tools/testing/kunit/kunit.py
> > +++ b/tools/testing/kunit/kunit.py
> > @@ -70,10 +70,10 @@ def build_tests(linux: kunit_kernel.LinuxSourceTree,
> >         kunit_parser.print_with_timestamp('Building KUnit Kernel ...')
> >
> >         build_start = time.time()
> > -       success = linux.build_um_kernel(request.alltests,
> > -                                       request.jobs,
> > -                                       request.build_dir,
> > -                                       request.make_options)
> > +       success = linux.build_kernel(request.alltests,
> > +                                    request.jobs,
> > +                                    request.build_dir,
> > +                                    request.make_options)
> >         build_end = time.time()
> >         if not success:
> >                 return KunitResult(KunitStatus.BUILD_FAILURE,
> > @@ -187,6 +187,14 @@ def add_common_opts(parser) -> None:
> >                              help='Path to Kconfig fragment that enables KUnit tests',
> >                              metavar='kunitconfig')
> >
> > +       parser.add_argument('--arch',
> > +                           help='Specifies the architecture to run tests under.',
> > +                           type=str, default='um', metavar='arch')
> 
> It'd be nice to note explicitly that non-'um' values here will run under qemu.

Good point. Will fix.

> > +
> > +       parser.add_argument('--cross_compile',
> > +                           help='Sets make\'s CROSS_COMPILE variable.',
> > +                           metavar='cross_compile')
> > +
> 
> It'd be nice to have a slightly more detailed description here (that
> its the compiler name's prefix or something).

How about?:

Sets make's CROSS_COMPILE variable; it should be set to a toolchain path
prefix (the prefix of gcc and other tools in your toolchain, for example
`sparc64-linux-gnu-` if you have the sparc toolchain installed on your
system, or `$HOME/toolchains/microblaze/gcc-9.2.0-nolibc/microblaze-linux/bin/microblaze-linux-`
if you have downloaded the microblaze toolchain from the 0-day website
to a directory in your home directory called `toolchains`).

> >  def add_build_opts(parser) -> None:
> >         parser.add_argument('--jobs',
> >                             help='As in the make command, "Specifies  the number of '
> > @@ -268,7 +276,10 @@ def main(argv, linux=None):
> >                         os.mkdir(cli_args.build_dir)
> >
> >                 if not linux:
> > -                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir, kunitconfig_path=cli_args.kunitconfig)
> > +                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
> > +                                       kunitconfig_path=cli_args.kunitconfig,
> > +                                       arch=cli_args.arch,
> > +                                       cross_compile=cli_args.cross_compile)
> >
> >                 request = KunitRequest(cli_args.raw_output,
> >                                        cli_args.timeout,
> > @@ -287,7 +298,9 @@ def main(argv, linux=None):
> >                         os.mkdir(cli_args.build_dir)
> >
> >                 if not linux:
> > -                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir, kunitconfig_path=cli_args.kunitconfig)
> > +                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
> > +                                       kunitconfig_path=cli_args.kunitconfig,
> > +                                       arch=cli_args.arch)
> >
> >                 request = KunitConfigRequest(cli_args.build_dir,
> >                                              cli_args.make_options)
> > @@ -299,7 +312,9 @@ def main(argv, linux=None):
> >                         sys.exit(1)
> >         elif cli_args.subcommand == 'build':
> >                 if not linux:
> > -                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir, kunitconfig_path=cli_args.kunitconfig)
> > +                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
> > +                                       kunitconfig_path=cli_args.kunitconfig,
> > +                                       arch=cli_args.arch)
> 
> Why aren't we passing cross_compile through here? It's pretty
> important for the 'build' step.

Good catch. Will fix.

> >
> >                 request = KunitBuildRequest(cli_args.jobs,
> >                                             cli_args.build_dir,
> > @@ -313,7 +328,9 @@ def main(argv, linux=None):
> >                         sys.exit(1)
> >         elif cli_args.subcommand == 'exec':
> >                 if not linux:
> > -                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir)
> > +                       linux = kunit_kernel.LinuxSourceTree(cli_args.build_dir,
> > +                                       kunitconfig_path=cli_args.kunitconfig,
> > +                                       arch=cli_args.arch)
> >
> >                 exec_request = KunitExecRequest(cli_args.timeout,
> >                                                 cli_args.build_dir,
> > diff --git a/tools/testing/kunit/kunit_config.py b/tools/testing/kunit/kunit_config.py
> > index 1e2683dcc0e7a..07d76be392544 100644
> > --- a/tools/testing/kunit/kunit_config.py
> > +++ b/tools/testing/kunit/kunit_config.py
> > @@ -53,7 +53,7 @@ class Kconfig(object):
> >                 return True
> >
> >         def write_to_file(self, path: str) -> None:
> > -               with open(path, 'w') as f:
> > +               with open(path, 'a+') as f:
> >                         for entry in self.entries():
> >                                 f.write(str(entry) + '\n')
> >
> > diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
> > index 7d5b77967d48f..b8b3b76aaa17e 100644
> > --- a/tools/testing/kunit/kunit_kernel.py
> > +++ b/tools/testing/kunit/kunit_kernel.py
> > @@ -15,6 +15,8 @@ from typing import Iterator
> >
> >  from contextlib import ExitStack
> >
> > +from collections import namedtuple
> > +
> >  import kunit_config
> >  import kunit_parser
> >
> > @@ -40,6 +42,10 @@ class BuildError(Exception):
> >  class LinuxSourceTreeOperations(object):
> >         """An abstraction over command line operations performed on a source tree."""
> >
> > +       def __init__(self, linux_arch, cross_compile):
> > +               self._linux_arch = linux_arch
> > +               self._cross_compile = cross_compile
> > +
> >         def make_mrproper(self) -> None:
> >                 try:
> >                         subprocess.check_output(['make', 'mrproper'], stderr=subprocess.STDOUT)
> > @@ -48,12 +54,18 @@ class LinuxSourceTreeOperations(object):
> >                 except subprocess.CalledProcessError as e:
> >                         raise ConfigError(e.output.decode())
> >
> > +       def make_arch_qemuconfig(self, build_dir):
> > +               pass
> > +
> >         def make_olddefconfig(self, build_dir, make_options) -> None:
> > -               command = ['make', 'ARCH=um', 'olddefconfig']
> > +               command = ['make', 'ARCH=' + self._linux_arch, 'olddefconfig']
> > +               if self._cross_compile:
> > +                       command += ['CROSS_COMPILE=' + self._cross_compile]
> >                 if make_options:
> >                         command.extend(make_options)
> >                 if build_dir:
> >                         command += ['O=' + build_dir]
> > +               print(' '.join(command))
> >                 try:
> >                         subprocess.check_output(command, stderr=subprocess.STDOUT)
> >                 except OSError as e:
> > @@ -61,6 +73,154 @@ class LinuxSourceTreeOperations(object):
> >                 except subprocess.CalledProcessError as e:
> >                         raise ConfigError(e.output.decode())
> >
> > +       def make(self, jobs, build_dir, make_options) -> None:
> > +               command = ['make', 'ARCH=' + self._linux_arch, '--jobs=' + str(jobs)]
> > +               if make_options:
> > +                       command.extend(make_options)
> > +               if self._cross_compile:
> > +                       command += ['CROSS_COMPILE=' + self._cross_compile]
> > +               if build_dir:
> > +                       command += ['O=' + build_dir]
> > +               print(' '.join(command))
> > +               try:
> > +                       proc = subprocess.Popen(command,
> > +                                               stderr=subprocess.PIPE,
> > +                                               stdout=subprocess.DEVNULL)
> > +               except OSError as e:
> > +                       raise BuildError('Could not call execute make: ' + e)
> > +               except subprocess.CalledProcessError as e:
> > +                       raise BuildError(e.output)
> > +               _, stderr = proc.communicate()
> > +               if proc.returncode != 0:
> > +                       raise BuildError(stderr.decode())
> > +               if stderr:  # likely only due to build warnings
> > +                       print(stderr.decode())
> > +
> > +       def run(self, params, timeout, build_dir, outfile) -> None:
> > +               pass
> > +
> > +
> > +QemuArchParams = namedtuple('QemuArchParams', ['linux_arch',
> > +                                              'qemuconfig',
> > +                                              'qemu_arch',
> > +                                              'kernel_path',
> > +                                              'kernel_command_line',
> > +                                              'extra_qemu_params'])
> > +
> > +
> > +QEMU_ARCHS = {
> > +       'i386'          : QemuArchParams(linux_arch='i386',
> > +                               qemuconfig='CONFIG_SERIAL_8250=y\nCONFIG_SERIAL_8250_CONSOLE=y',
> 
> I'm not keen on these configs being condensed like this in the source.
> As mentioned below, moving the QemuArchParams to a separate file
> helps, but even then it'd be nice to at least have each entry on a
> separate line like with 'arm' below.

Good to note. I was not sure about the multiline strings, part of me
thought they were an improvement. Part of me thought they were horribly
ugly.

> The other option would be to have this as a path to a separate
> Kconfig/.kunitconfig file with these configs, rather than having them
> inline here. I fear that could lead to every architecture needing
> several support files, though some (e.g. x86/x86_64/alpha/sparc) could
> share a file.

Yeah, I went back and forth on it. Part of me thinks it is nice to have
all your configs in one place. The other part of me agrees with what you
said here. I think I will stick with the way I am doing it now for no
other reason than that's the way I already have it. If someone feels
strongly though, I would be happy to change it.

> > +                               qemu_arch='x86_64',
> > +                               kernel_path='arch/x86/boot/bzImage',
> > +                               kernel_command_line='console=ttyS0',
> > +                               extra_qemu_params=['']),
> > +       'x86_64'        : QemuArchParams(linux_arch='x86_64',
> > +                               qemuconfig='CONFIG_SERIAL_8250=y\nCONFIG_SERIAL_8250_CONSOLE=y',
> > +                               qemu_arch='x86_64',
> > +                               kernel_path='arch/x86/boot/bzImage',
> > +                               kernel_command_line='console=ttyS0',
> > +                               extra_qemu_params=['']),
> > +       'arm'           : QemuArchParams(linux_arch='arm',
> > +                               qemuconfig='''CONFIG_ARCH_VIRT=y
> > +CONFIG_SERIAL_AMBA_PL010=y
> > +CONFIG_SERIAL_AMBA_PL010_CONSOLE=y
> > +CONFIG_SERIAL_AMBA_PL011=y
> > +CONFIG_SERIAL_AMBA_PL011_CONSOLE=y''',
> > +                               qemu_arch='arm',
> > +                               kernel_path='arch/arm/boot/zImage',
> > +                               kernel_command_line='console=ttyAMA0',
> > +                               extra_qemu_params=['-machine virt']),
> > +       'arm64'         : QemuArchParams(linux_arch='arm64',
> > +                               qemuconfig='''CONFIG_SERIAL_AMBA_PL010=y
> > +CONFIG_SERIAL_AMBA_PL010_CONSOLE=y
> > +CONFIG_SERIAL_AMBA_PL011=y
> > +CONFIG_SERIAL_AMBA_PL011_CONSOLE=y''',
> > +                               qemu_arch='aarch64',
> > +                               kernel_path='arch/arm64/boot/Image.gz',
> > +                               kernel_command_line='console=ttyAMA0',
> > +                               extra_qemu_params=['-machine virt', '-cpu cortex-a57']),
> > +       'alpha'         : QemuArchParams(linux_arch='alpha',
> > +                               qemuconfig='CONFIG_SERIAL_8250=y\nCONFIG_SERIAL_8250_CONSOLE=y',
> > +                               qemu_arch='alpha',
> > +                               kernel_path='arch/alpha/boot/vmlinux',
> > +                               kernel_command_line='console=ttyS0',
> > +                               extra_qemu_params=['']),
> > +       'powerpc'       : QemuArchParams(linux_arch='powerpc',
> > +                               qemuconfig='CONFIG_PPC64=y\nCONFIG_SERIAL_8250=y\nCONFIG_SERIAL_8250_CONSOLE=y\nCONFIG_HVC_CONSOLE=y',
> > +                               qemu_arch='ppc64',
> > +                               kernel_path='vmlinux',
> > +                               kernel_command_line='console=ttyS0',
> > +                               extra_qemu_params=['-M pseries', '-cpu power8']),
> > +       'riscv'         : QemuArchParams(linux_arch='riscv',
> > +                               qemuconfig='CONFIG_SOC_VIRT=y\nCONFIG_SERIAL_8250=y\nCONFIG_SERIAL_8250_CONSOLE=y\nCONFIG_SERIAL_OF_PLATFORM=y\nCONFIG_SERIAL_EARLYCON_RISCV_SBI=y',
> > +                               qemu_arch='riscv64',
> > +                               kernel_path='arch/riscv/boot/Image',
> > +                               kernel_command_line='console=ttyS0',
> > +                               extra_qemu_params=['-machine virt', '-cpu rv64', '-bios opensbi-riscv64-generic-fw_dynamic.bin']),
> > +       's390'          : QemuArchParams(linux_arch='s390',
> > +                               qemuconfig='CONFIG_EXPERT=y\nCONFIG_TUNE_ZEC12=y\nCONFIG_NUMA=y\nCONFIG_MODULES=y',
> > +                               qemu_arch='s390x',
> > +                               kernel_path='arch/s390/boot/bzImage',
> > +                               kernel_command_line='console=ttyS0',
> > +                               extra_qemu_params=[
> > +                                               '-machine s390-ccw-virtio',
> > +                                               '-cpu qemu',]),
> > +       'sparc'         : QemuArchParams(linux_arch='sparc',
> > +                               qemuconfig='CONFIG_SERIAL_8250=y\nCONFIG_SERIAL_8250_CONSOLE=y',
> > +                               qemu_arch='sparc',
> > +                               kernel_path='arch/sparc/boot/zImage',
> > +                               kernel_command_line='console=ttyS0 mem=256M',
> > +                               extra_qemu_params=['-m 256']),
> > +}
> 
> So, as mentioned, I agree with Daniel in thinking that this really
> doesn't belong here. Ideally, I think these configs should be
> specified somewhere else, either as a (alas, very long) series of
> command-line arguments, or in a separate file. Moving them to a single
> 'qemu_configs.py' as Daniel mentioned would be an improvement, but
> IMHO still falls well short of ideal. I think each config should be in
> its own file, as there are several reasons someone might want to have
> multiple different configs for a given architecture and we'll want
> people to be able to add/remove these easily in their own
> environments.
> 
> The proposed solution of having each config in a separate file --
> which we discussed offline -- is a big improvement:
> https://kunit-review.googlesource.com/c/linux/+/4489

Good to know, I will incorporate it into the next revision.

> I still think that the python format here is a bit verbose and ugly,
> but it's probably worth it compared to adding a parser for a whole new
> type of config file.

That's where I am at with it. I feel as though I have added enough
parsers to the kernel tree. :-)

> Similarly, I'm not sure about keeping a separate
> qemu_configs.py around with the builtin defaults rather than just
> having them all as separate files all the time. (Even appreciating
> that that requires some filename magic to find the correct file.)
> These are all more nitpicky though.

This raises an excellent point, what should we do with the --arch flag
if we add the --qemu_config flag?

The only reason I just added --qemu_config without touching the existing
configs was just because I was being lazy; nevertheless, my original
plan was just to drop --arch entirely and just expect the user to know
that to run KUnit on i386 you need:

tools/testing/kunit/kunit.py run --qemu_config=./tools/testing/kunit/qemu_configs/i386.py

and to run KUnit on arm you need:

tools/testing/kunit/kunit.py run --qemu_config=./tools/testing/kunit/qemu_configs/arm.py --cross_compile=arm-linux-gnueabihf-

(or something like that).

Is that OK, or as you hint, should we do some file system magic so that
you have the option of

tools/testing/kunit/kunit.py run --qemu_config=./tools/testing/kunit/qemu_configs/i386.py

OR

tools/testing/kunit/kunit.py run --arch=i386

?

My preference is for the former since it is more explicit about what it
is doing.

> > +
> > +class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
> > +
> > +       def __init__(self, qemu_arch_params, cross_compile):
> > +               super().__init__(linux_arch=qemu_arch_params.linux_arch,
> > +                                cross_compile=cross_compile)
> > +               self._qemuconfig = qemu_arch_params.qemuconfig
> > +               self._qemu_arch = qemu_arch_params.qemu_arch
> > +               self._kernel_path = qemu_arch_params.kernel_path
> > +               print(self._kernel_path)
> > +               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, build_dir):
> > +               qemuconfig = kunit_config.Kconfig()
> > +               qemuconfig.parse_from_string(self._qemuconfig)
> > +               qemuconfig.write_to_file(get_kconfig_path(build_dir))
> > +
> > +       def run(self, params, timeout, build_dir, outfile):
> > +               kernel_path = os.path.join(build_dir, self._kernel_path)
> > +               qemu_command = ['qemu-system-' + self._qemu_arch,
> > +                               '-nodefaults',
> > +                               '-m', '1024',
> > +                               '-kernel', kernel_path,
> > +                               '-append', '\'' + ' '.join(params + [self._kernel_command_line]) + '\'',
> > +                               '-no-reboot',
> > +                               '-nographic',
> > +                               '-serial stdio'] + self._extra_qemu_params
> > +               print(' '.join(qemu_command))
> > +               with open(outfile, 'w') as output:
> > +                       process = subprocess.Popen(' '.join(qemu_command),
> > +                                                  stdin=subprocess.PIPE,
> > +                                                  stdout=output,
> > +                                                  stderr=subprocess.STDOUT,
> > +                                                  text=True, shell=True)
> > +               try:
> > +                       process.wait(timeout=timeout)
> > +               except Exception as e:
> > +                       print(e)
> > +                       process.terminate()
> > +               return process
> > +
> > +class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
> > +       """An abstraction over command line operations performed on a source tree."""
> > +
> > +       def __init__(self):
> > +               super().__init__(linux_arch='um', cross_compile=None)
> > +
> 
> Why is cross_compile None here? Shouldn't it be possible to cross
> compile UML kernels? (This should, I think, be possible for i386 on an
> x86_64 host, for instance.)

Fair point. Will fix.

> >         def make_allyesconfig(self, build_dir, make_options) -> None:
> >                 kunit_parser.print_with_timestamp(
> >                         'Enabling all CONFIGs for UML...')
> > @@ -83,32 +243,16 @@ class LinuxSourceTreeOperations(object):
> >                 kunit_parser.print_with_timestamp(
> >                         'Starting Kernel with all configs takes a few minutes...')
> >
> > -       def make(self, jobs, build_dir, make_options) -> None:
> > -               command = ['make', 'ARCH=um', '--jobs=' + str(jobs)]
> > -               if make_options:
> > -                       command.extend(make_options)
> > -               if build_dir:
> > -                       command += ['O=' + build_dir]
> > -               try:
> > -                       proc = subprocess.Popen(command,
> > -                                               stderr=subprocess.PIPE,
> > -                                               stdout=subprocess.DEVNULL)
> > -               except OSError as e:
> > -                       raise BuildError('Could not call make command: ' + str(e))
> > -               _, stderr = proc.communicate()
> > -               if proc.returncode != 0:
> > -                       raise BuildError(stderr.decode())
> > -               if stderr:  # likely only due to build warnings
> > -                       print(stderr.decode())
> > -
> > -       def linux_bin(self, params, timeout, build_dir) -> None:
> > +       def run(self, params, timeout, build_dir, outfile):
> >                 """Runs the Linux UML binary. Must be named 'linux'."""
> >                 linux_bin = get_file_path(build_dir, 'linux')
> >                 outfile = get_outfile_path(build_dir)
> >                 with open(outfile, 'w') as output:
> >                         process = subprocess.Popen([linux_bin] + params,
> > +                                                  stdin=subprocess.PIPE,
> >                                                    stdout=output,
> > -                                                  stderr=subprocess.STDOUT)
> > +                                                  stderr=subprocess.STDOUT,
> > +                                                  text=True)
> >                         process.wait(timeout)
> >
> >  def get_kconfig_path(build_dir) -> str:
> > @@ -123,10 +267,17 @@ def get_outfile_path(build_dir) -> str:
> >  class LinuxSourceTree(object):
> >         """Represents a Linux kernel source tree with KUnit tests."""
> >
> > -       def __init__(self, build_dir: str, load_config=True, kunitconfig_path='') -> None:
> > +       def __init__(self, build_dir: str, load_config=True, kunitconfig_path='', arch=None, cross_compile=None) -> None:
> >                 signal.signal(signal.SIGINT, self.signal_handler)
> > -
> > -               self._ops = LinuxSourceTreeOperations()
> > +               self._ops = None
> > +               if arch is None or arch == 'um':
> > +                       self._arch = 'um'
> > +                       self._ops = LinuxSourceTreeOperationsUml()
> 
> Again, we should probably pass cross_compile through here.

Yep. Will do.

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