Re: [PATCH v4 15/16] vfio: selftests: Verify that opening VFIO device fails during Live Update

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Unconditionally testing all legacy IOMMU modes will cause the selftest to crash on kernels lacking legacy VFIO support.
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commit 15d06d7e17051c89eae8198f7b5a759b9968ab87
Author: David Matlack <dmatlack@google.com>

vfio: selftests: Verify that opening VFIO device fails during Live Update

Verify that opening a VFIO device through its cdev file and via
VFIO_GROUP_GET_DEVICE_FD both fail with -EBUSY if the device was
preserved across a Live Update.

> diff --git a/tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c b/tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c
> index 15b3e3af91d1e..65c48196e44e7 100644
> --- a/tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c
> +++ b/tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c

[ ... ]

> @@ -36,6 +36,42 @@ static void before_kexec(int luo_fd)
>  	daemonize_and_wait();
>  }
>  
> +static void check_open_vfio_device_fails(void)
> +{

[ ... ]

> +	for (i = 0; i < nr_iommu_modes; i++) {
> +		if (!iommu_modes[i].container_path)
> +			continue;
> +
> +		iommu = iommu_init(iommu_modes[i].name);

Does this introduce a regression on kernels lacking legacy VFIO support?

If the kernel is compiled without legacy VFIO support (CONFIG_VFIO_GROUP=n),
calling iommu_init() on a legacy container path like /dev/vfio/vfio will
fail.

This causes iommu_init() to fail its internal assertion, calling
VFIO_LOG_AND_EXIT() and aborting the process. Because this standalone test
program does not use kselftest_harness process isolation, crashing here
prevents it from verifying the core live update functionality.

Could we verify the container path is accessible before calling iommu_init()
so unsupported modes can be gracefully skipped?

> +
> +		device = vfio_pci_device_alloc(device_bdf, iommu);

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260511234802.2280368-1-vipinsh@google.com?part=15