Shuai and Kevin found a few bugs in the pci_dev_reset_iommu_prepare/done()
helpers when used to handle some corner cases:
 - Nested callbacks
 - Multi-device groups
 - UAF due to concurrent detach

This needs some substantial rework by tracking device reset states on a per
gdev basis. This series includes a few patches addressing them. Most of the
patches are reviewed previously in a single patch v6. As we found more bugs
during the reviews, I split that v6 to smaller patches so each of them will
be cleaner. IOW, the git-diff from PATCH 1-4 is identical to v6.

This is on Github:
https://github.com/nicolinc/iommufd/commits/fix_iommu_reset-v7

Changelog
 v7:
  * Add Reviewed-by tags
  * Split v6 into smaller patches
  * Add one patch to fix UAF during detach()
  * Add one patch to fix unnecessary ATS invalidation
 v6:
  https://lore.kernel.org/all/20260407194644.171304-1-nicolinc@nvidia.com/
  * Update inline comments and commit message
  * Add "max_pasids > 0" condition in both helpers
 v5:
  https://lore.kernel.org/all/20260404050243.141366-1-nicolinc@nvidia.com/
  * Add 'blocked' to fix iommu_driver_get_domain_for_dev() return.
 v4:
  https://lore.kernel.org/all/20260324014056.36103-1-nicolinc@nvidia.com/
  * Rename 'reset_cnt' to 'recovery_cnt'
 v3:
  https://lore.kernel.org/all/20260321223930.10836-1-nicolinc@nvidia.com/
  * Turn prepare()/done() to be per-gdev
  * Use reset_depth to track nested re-entries
  * Replace group->resetting_domain with a reset_cnt
 v2:
  https://lore.kernel.org/all/20260319043135.1153534-1-nicolinc@nvidia.com/
  * Fix in the helpers by allowing re-entry
 v1:
  https://lore.kernel.org/all/20260318220028.1146905-1-nicolinc@nvidia.com/

Nicolin Chen (6):
  iommu: Fix kdocs of pci_dev_reset_iommu_done()
  iommu: Replace per-group resetting_domain with per-gdev blocked flag
  iommu: Fix pasid attach in pci_dev_reset_iommu_prepare/done()
  iommu: Fix nested pci_dev_reset_iommu_prepare/done()
  iommu: Fix ATS invalidation timeouts during
    __iommu_remove_group_pasid()
  iommu: Fix UAF in pci_dev_reset_iommu_done() due to concurrent detach

 drivers/iommu/iommu.c | 163 ++++++++++++++++++++++++++++++++----------
 1 file changed, 124 insertions(+), 39 deletions(-)

-- 
2.43.0