[PATCH RFC v7 0/3] riscv: mm: Add soft-dirty and uffd-wp support

[Chunyan Zhang]

This patchset adds soft dirty and userfaultfd write protect tracking 
support 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 v6.15-rc1.

V7:
- 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 at 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/Svrsw60t59b.git

Chunyan Zhang (3):
  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                    |  15 +++
 arch/riscv/include/asm/hwcap.h        |   1 +
 arch/riscv/include/asm/pgtable-bits.h |  37 +++++++
 arch/riscv/include/asm/pgtable.h      | 136 +++++++++++++++++++++++++-
 arch/riscv/kernel/cpufeature.c        |   1 +
 5 files changed, 188 insertions(+), 2 deletions(-)

-- 
2.34.1