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

[Samiullah Khawaja <skhawaja@google.com>]

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@google.com>
>> Signed-off-by: YiFei Zhu <zhuyifei@google.com>
>> ---
>>  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
>>
>> diff --git a/tools/testing/selftests/iommu/Makefile b/tools/testing/selftests/iommu/Makefile
>> index 84abeb2f0949..263195af4d6a 100644
>> --- a/tools/testing/selftests/iommu/Makefile
>> +++ b/tools/testing/selftests/iommu/Makefile
>> @@ -7,4 +7,16 @@ TEST_GEN_PROGS :=
>>  TEST_GEN_PROGS += iommufd
>>  TEST_GEN_PROGS += iommufd_fail_nth
>>
>> +TEST_GEN_PROGS_EXTENDED += iommufd_liveupdate
>> +
>>  include ../lib.mk
>> +include ../liveupdate/lib/libliveupdate.mk
>> +
>> +CFLAGS += -I$(top_srcdir)/tools/include
>> +CFLAGS += -MD
>> +CFLAGS += $(EXTRA_CFLAGS)
>> +
>> +$(TEST_GEN_PROGS_EXTENDED): %: %.o $(LIBLIVEUPDATE_O)
>> +	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH) $< $(LIBLIVEUPDATE_O) $(LDLIBS) -static -o $@
>> +
>> +EXTRA_CLEAN += $(LIBLIVEUPDATE_O)
>> diff --git a/tools/testing/selftests/iommu/iommufd_liveupdate.c b/tools/testing/selftests/iommu/iommufd_liveupdate.c
>> new file mode 100644
>> index 000000000000..8b4ea9f2b7e9
>> --- /dev/null
>> +++ b/tools/testing/selftests/iommu/iommufd_liveupdate.c
>> @@ -0,0 +1,209 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +
>> +/*
>> + * Copyright (c) 2025, Google LLC.
>> + * Samiullah Khawaja <skhawaja@google.com>
>> + */
>> +
>> +#include <fcntl.h>
>> +#include <sys/ioctl.h>
>> +#include <sys/mman.h>
>> +#include <stdbool.h>
>> +#include <unistd.h>
>> +
>> +#define __EXPORTED_HEADERS__
>> +#include <linux/iommufd.h>
>> +#include <linux/types.h>
>> +#include <linux/vfio.h>
>> +#include <linux/sizes.h>
>> +#include <libliveupdate.h>
>> +
>> +#include "../kselftest.h"
>> +
>> +#define ksft_assert(condition) \
>> +	do { if (!(condition)) \
>> +	ksft_exit_fail_msg("Failed: %s at %s %d: %s\n", \
>> +	#condition, __FILE__, __LINE__, strerror(errno)); } while (0)
>> +
>> +int setup_cdev(const char *vfio_cdev_path)
>> +{
>> +	int cdev_fd;
>> +
>> +	cdev_fd = open(vfio_cdev_path, O_RDWR);
>> +	if (cdev_fd < 0)
>> +		ksft_exit_skip("Failed to open VFIO cdev: %s\n", vfio_cdev_path);
>> +
>> +	return cdev_fd;
>> +}
>> +
>> +int open_iommufd(void)
>> +{
>> +	int iommufd;
>> +
>> +	iommufd = open("/dev/iommu", O_RDWR);
>> +	if (iommufd < 0)
>> +		ksft_exit_skip("Failed to open /dev/iommu. IOMMUFD support not enabled.\n");
>> +
>> +	return iommufd;
>> +}
>> +
>> +int setup_iommufd(int iommufd, int memfd, int cdev_fd, int hwpt_token)
>> +{
>> +	int ret;
>> +
>> +	struct vfio_device_bind_iommufd bind = {
>> +		.argsz = sizeof(bind),
>> +		.flags = 0,
>> +	};
>> +	struct iommu_ioas_alloc alloc_data = {
>> +		.size = sizeof(alloc_data),
>> +		.flags = 0,
>> +	};
>> +	struct iommu_hwpt_alloc hwpt_alloc = {
>> +		.size = sizeof(hwpt_alloc),
>> +		.flags = 0,
>> +	};
>> +	struct vfio_device_attach_iommufd_pt attach_data = {
>> +		.argsz = sizeof(attach_data),
>> +		.flags = 0,
>> +	};
>> +	struct iommu_hwpt_lu_set_preserve set_preserve = {
>> +		.size = sizeof(set_preserve),
>> +		.hwpt_token = hwpt_token,
>> +	};
>> +	struct iommu_ioas_map_file map_file = {
>> +		.size = sizeof(map_file),
>> +		.length = SZ_1M,
>> +		.flags = IOMMU_IOAS_MAP_WRITEABLE | IOMMU_IOAS_MAP_READABLE,
>> +		.iova = SZ_4G,
>> +		.fd = memfd,
>> +		.start = 0,
>> +	};
>> +
>> +	bind.iommufd = iommufd;
>> +	ret = ioctl(cdev_fd, VFIO_DEVICE_BIND_IOMMUFD, &bind);
>> +	ksft_assert(!ret);
>> +
>> +	ret = ioctl(iommufd, IOMMU_IOAS_ALLOC, &alloc_data);
>> +	ksft_assert(!ret);
>> +
>> +	hwpt_alloc.dev_id = bind.out_devid;
>> +	hwpt_alloc.pt_id = alloc_data.out_ioas_id;
>> +	ret = ioctl(iommufd, IOMMU_HWPT_ALLOC, &hwpt_alloc);
>> +	ksft_assert(!ret);
>> +
>> +	attach_data.pt_id = hwpt_alloc.out_hwpt_id;
>> +	ret = ioctl(cdev_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_data);
>> +	ksft_assert(!ret);
>> +
>> +	map_file.ioas_id = alloc_data.out_ioas_id;
>> +	ret = ioctl(iommufd, IOMMU_IOAS_MAP_FILE, &map_file);
>> +	ksft_assert(!ret);
>> +
>> +	set_preserve.hwpt_id = attach_data.pt_id;
>> +	ret = ioctl(iommufd, IOMMU_HWPT_LU_SET_PRESERVE, &set_preserve);
>> +	ksft_assert(!ret);
>> +
>> +	return ret;
>> +}
>> +
>> +static int create_sealed_memfd(size_t size)
>> +{
>> +	int fd, ret;
>> +
>> +	fd = memfd_create("buffer", MFD_ALLOW_SEALING);
>> +	ksft_assert(fd > 0);
>> +
>> +	ret = ftruncate(fd, size);
>> +	ksft_assert(!ret);
>> +
>> +	ret = fcntl(fd, F_ADD_SEALS,
>> +		    F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL);
>> +	ksft_assert(!ret);
>> +
>> +	return fd;
>> +}
>> +
>> +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.
>
>> +{
>> +	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