[PATCH v9 0/5] riscv: mm: Add soft-dirty and uffd-wp support

[Chunyan Zhang <zhangchunyan@iscas.ac.cn>]

This patchset adds support for Svrsw60t59b [1] extension which is ratified now,
also soft dirty and userfaultfd write protect tracking for RISC-V.

This patchset has been tested with kselftest mm suite in which soft-dirty, 
madv_populate, test_unmerge_uffd_wp, and uffd-unit-tests run and pass,
and no regressions are observed in any of the other tests.

This patchset applies on top of v6.17-rc4.

V9:
- Add pte_soft_dirty/uffd_wp_available() API to allow dynamically checking
  if the PTE bit is available for the platform on which the kernel is running.

V8: (https://lore.kernel.org/all/20250619065232.1786470-1-zhangchunyan@iscas.ac.cn/)
- Rebase on v6.16-rc1;
- Add dependencies to MMU && 64BIT for RISCV_ISA_SVRSW60T59B;
- Use 'Svrsw60t59b' instead of 'SVRSW60T59B' in Kconfig help paragraph;
- Add Alex's Reviewed-by tag in patch 1.

V7: (https://lore.kernel.org/all/20250409095320.224100-1-zhangchunyan@iscas.ac.cn/)
- Add Svrsw60t59b [1] extension support;
- Have soft-dirty and uffd-wp depending on the Svrsw60t59b extension to
  avoid crashes for the hardware which don't have this extension.

V6:
- Changes to use bits 59-60 which are supported by extension Svrsw60t59b
  for soft dirty and userfaultfd write protect tracking.

V5:
- Fixed typos and corrected some words in Kconfig and commit message;
- Removed pte_wrprotect() from pte_swp_mkuffd_wp(), this is a copy-paste
  error;
- Added Alex's Reviewed-by tag in patch 2.

V4:
- Added bit(4) descriptions into "Format of swap PTE".

V3:
- Fixed the issue reported by kernel test irobot <lkp@intel.com>.

V1 -> V2:
- Add uffd-wp supported;
- Make soft-dirty uffd-wp and devmap mutually exclusive which all use
  the same PTE bit;
- Add test results of CRIU in the cover-letter.

[1] https://github.com/riscv-non-isa/riscv-iommu/pull/543

Chunyan Zhang (5):
  mm: softdirty: Add pte_soft_dirty_available()
  mm: uffd_wp: Add pte_uffd_wp_available()
  riscv: Add RISC-V Svrsw60t59b extension support
  riscv: mm: Add soft-dirty page tracking support
  riscv: mm: Add uffd write-protect support

 arch/riscv/Kconfig                    |  16 +++
 arch/riscv/include/asm/hwcap.h        |   1 +
 arch/riscv/include/asm/pgtable-bits.h |  37 +++++++
 arch/riscv/include/asm/pgtable.h      | 140 +++++++++++++++++++++++++-
 arch/riscv/kernel/cpufeature.c        |   1 +
 fs/proc/task_mmu.c                    |  12 ++-
 fs/userfaultfd.c                      |  25 +++--
 include/asm-generic/pgtable_uffd.h    |  12 +++
 include/linux/mm_inline.h             |   6 +-
 include/linux/pgtable.h               |  10 ++
 include/linux/userfaultfd_k.h         |  44 +++++---
 mm/debug_vm_pgtable.c                 |   9 +-
 mm/huge_memory.c                      |  13 +--
 mm/internal.h                         |   2 +-
 mm/memory.c                           |   6 +-
 mm/mremap.c                           |  13 +--
 mm/userfaultfd.c                      |  12 +--
 17 files changed, 302 insertions(+), 57 deletions(-)

-- 
2.34.1