[PATCH v2 0/2] vfio/pci: fix huge_fault write handling and add selftest

[Mina Almasry <almasrymina@google.com>]

Fix vfio_pci_vmf_insert_pfn() passing write=false to
vmf_insert_pfn_pmd() and vmf_insert_pfn_pud(), which causes an infinite
write page-fault loop when vma->vm_page_prot starts read-only (such as
after soft-dirty clearing via /proc/<pid>/clear_refs in CRIU or live
migration, or on arm64 without hardware DBM), and add a companion VFIO
PCI selftest covering both read-then-write upgrade and initial write
faults after clear_refs.

Changes in v2:
- Expand Patch 1/2 commit log with practical trigger scenarios (CRIU /
  clear_refs soft-dirty clearing and arm64 software dirty tracking) for
  stable backport evaluation, per Alex Williamson.
- Drop the Assisted-by tag from Patch 1/2.
- Add Patch 2/2 selftest in vfio_pci_device_test (bar_write_fault_after_clear_refs),
  as suggested by Alex Williamson.
- Link to v1: https://lore.kernel.org/all/20261024015540.538758-1-almasrymina@google.com/

Mina Almasry (2):
  vfio/pci: pass FAULT_FLAG_WRITE to vmf_insert_pfn_pmd/pud()
  vfio: selftests: Test BAR write faults after clear_refs

 drivers/vfio/pci/vfio_pci_core.c              |  6 +-
 .../selftests/vfio/vfio_pci_device_test.c     | 83 +++++++++++++++++++
 2 files changed, 87 insertions(+), 2 deletions(-)


base-commit: 076d7e989cb69f6ded7d60f2a080eb909930061b
-- 
2.56.0.385.gac671c819a-goog