It is to solve the lifecycle issue that vdevice may outlive idevice. It
is a prerequisite for TIO, to ensure extra secure configurations (e.g.
TSM Bind/Unbind) against vdevice could be rolled back on idevice unbind,
so that VFIO could still work on the physical device without surprise.

Changelog:
v4:
 - Rebase to iommufd for-next.
 - A new patch to roll back iommufd_object_alloc_ucmd() for vdevice.
 - Fix the mistake trying to xa_destroy ictx->groups on
   iommufd_fops_release().
 - Move 'empty' flag inside destroy loop for iommufd_fops_release().
 - Refactor vdev/idev destroy syncing.
   - Drop the iommufd_vdevice_abort() reentrant idea.
   - A new patch that adds pre_destroy() op.
   - Hold short term reference during the whole vdevice's lifecycle.
   - Wait on short term reference on idev's pre_destroy().
   - Add a 'destroying' flag for idev to prevent new reference after
     pre_destroy().
 - Rephrase/fix some comments.
 - Add review tags.

v3: https://lore.kernel.org/linux-iommu/20250627033809.1730752-1-yilun.xu@linux.intel.com/
 - No bother clean each tombstone in iommufd_fops_release().
 - Drop vdev->ictx initialization fix patch.
 - Optimize control flow in iommufd_device_remove_vdev().
 - Make iommufd_vdevice_abort() reentrant.
 - Call iommufd_vdevice_abort() directly instead of waiting for it.
 - Rephrase/fix some comments.
 - A new patch to remove vdev->dev.
 - A new patch to explicitly skip existing viommu tests for no_iommu.
 - Also skip vdevice tombstone test for no_iommu.
 - Allow me to add SoB from Aneesh.

v2: https://lore.kernel.org/linux-iommu/20250623094946.1714996-1-yilun.xu@linux.intel.com/

v1/rfc: https://lore.kernel.org/linux-iommu/20250610065146.1321816-1-aneesh.kumar@kernel.org/

The series is based on iommufd for-next


Xu Yilun (7):
  iommufd/viommu: Roll back to use iommufd_object_alloc() for vdevice
  iommufd: Add iommufd_object_tombstone_user() helper
  iommufd: Add a pre_destroy() op for objects
  iommufd: Destroy vdevice on idevice destroy
  iommufd/vdevice: Remove struct device reference from struct vdevice
  iommufd/selftest: Explicitly skip tests for inapplicable variant
  iommufd/selftest: Add coverage for vdevice tombstone

 drivers/iommu/iommufd/device.c          |  51 ++++
 drivers/iommu/iommufd/driver.c          |   4 +-
 drivers/iommu/iommufd/iommufd_private.h |  37 ++-
 drivers/iommu/iommufd/main.c            |  30 +-
 drivers/iommu/iommufd/viommu.c          |  64 +++-
 tools/testing/selftests/iommu/iommufd.c | 388 ++++++++++++------------
 6 files changed, 373 insertions(+), 201 deletions(-)


base-commit: 3e2a9811f6a9cefd310cc33cab73d5435b4a4caa
-- 
2.25.1