Re: [PATCH 14/14] iommufd/selftest: Add test to verify iommufd preservation

[Samiullah Khawaja]

On Fri, Mar 27, 2026 at 06:25:36PM +0000, Samiullah Khawaja wrote:
> On Wed, Mar 25, 2026 at 09:05:32PM +0000, Pranjal Shrivastava wrote:
> > On Tue, Feb 03, 2026 at 10:09:48PM +0000, Samiullah Khawaja wrote:
> > > Test iommufd preservation by setting up an iommufd and vfio cdev and
> > > preserve it across live update. Test takes VFIO cdev path of a device
> > > bound to vfio-pci driver and binds it to an iommufd being preserved. It
> > > also preserves the vfio cdev so the iommufd state associated with it is
> > > also preserved.
> > >
> > > The restore path is tested by restoring the preserved vfio cdev only.
> > > Test tries to finish the session without restoring iommufd and confirms
> > > that it fails.
> > >
> > > Signed-off-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>
> > > Signed-off-by: YiFei Zhu <zhuyifei@xxxxxxxxxx>
> > > ---
> > > tools/testing/selftests/iommu/Makefile        |  12 +
> > > .../selftests/iommu/iommufd_liveupdate.c      | 209 ++++++++++++++++++
> > > 2 files changed, 221 insertions(+)
> > > create mode 100644 tools/testing/selftests/iommu/iommufd_liveupdate.c
> > >
> > > +int main(int argc, char *argv[])
> >
> > The iommufd selftest directory heavily utilizes the standard kselftest
> > harness (TEST_F, EXPECT_EQ, ASSERT_EQ), by writing a raw main(), this
> > patch circumvents the standard test reporting structure (like returning 1
> > on argc < 2 instead of ksft_exit_skip(), and returning 0 at the end
> > instead of ksft_exit_pass() etc.). We should rewrite this cleanly
> > following the existing iommufd test infrastructure using TEST_F blocks.
>
> Agreed. Will do.

Thinking about this more, these liveupdate tests are two stage tests.
There is a run before liveupdate and there is a run after liveupdate. I
will have to use the luo_test mechanism here for this test. See example
usage in the kexec_test in the VFIO cdev preservation series:

https://lore.kernel.org/all/20260323235817.1960573-21-dmatlack@xxxxxxxxxx
> > > +{
> > > +	int iommufd, cdev_fd, memfd, luo, session, ret;
> > > +	const int token = 0x123456;
> > > +	const int cdev_token = 0x654321;
> > > +	const int hwpt_token = 0x789012;
> > > +	const int memfd_token = 0x890123;
> >
> > Shouldn't these be u64? Defining them as signed int-s undermines that
> > contract?
>
> Agreed. Will update.
> > > +
> > > +	if (argc < 2) {
> > > +		printf("Usage: ./iommufd_liveupdate <vfio_cdev_path>\n");
> > > +		return 1;
> > > +	}
> > > +
> > > +	luo = luo_open_device();
> > > +	ksft_assert(luo > 0);
> > > +
> > > +	session = luo_retrieve_session(luo, "iommufd-test");
> >
> > [ ---- >8 ---- ]
> >
> > Thanks,
> > Praan
>
> Thanks,
> Sami