[PATCH v2 00/15] riscv: add Svnapot PTE folding support

[Yunhui Cui]

Svnapot can encode a naturally aligned 64KB range as a single folded
PTE block. This series adds the RISC-V MM support needed to use that
encoding for suitable user mappings while preserving the generic MM view
of PAGE_SIZE PTEs.

The series starts by adding raw PTE helpers and switching architecture
page-table users that must see the encoded page-table entry to those raw
helpers. It then introduces Svnapot read-side and update helpers for
folded PTE ranges. Later patches make the generic PTE batch and leaf-size
interfaces work with the raw encoded view where required, avoid redundant
A/D aggregation and TLB flushes, optimize mprotect() for Svnapot ranges,
and request 64KB executable folios when Svnapot is available so text
mappings can benefit from lower iTLB pressure.

Dependency:
  - This series depends on the prerequisite RISC-V patch posted at:
    https://lore.kernel.org/all/20260618064406.14508-1-cuiyunhui@bytedance.com/

Changes in v2:
  - Rework the v1 7-patch series into 15 smaller patches: split raw PTE
    helper introduction from the architecture-user conversion, and split
    Svnapot contpte handling into read-side and update-side pieces.
  - Add the generic MM helper changes needed by folded Svnapot mappings,
    including folio-batch comparison flags, raw-entry leaf-size queries and
    fast-GUP-specific lockless PTE helpers.
  - Make the RISC-V pte_batch_hint() implementation honor folio batch
    flags, and preserve Svnapot leaf-size semantics via __ptep_leaf_size().
  - Add follow-up fixes and optimizations that were not in v1: avoid
    redundant A/D aggregation, avoid Svnapot consistency checks in
    ptep_get(), avoid A/D aggregation in fast-GUP, remove a redundant TLB
    flush, optimize mprotect() for Svnapot mappings, and request large
    executable folios when Svnapot is available.

Yunhui Cui (15):
  riscv: introduce raw PTE helpers
  riscv: switch arch page-table users to raw PTE helpers
  riscv/mm: implement Svnapot contpte read-side helpers
  riscv/mm: implement Svnapot contpte update helpers
  mm: extend pte batch and leaf-size helpers
  riscv: make pte_batch_hint() honor folio batch flags
  riscv/mm: preserve Svnapot leaf-size semantics for page-table
    consumers
  riscv/mm: avoid redundant Svnapot A/D aggregation
  riscv/mm: avoid Svnapot consistency checks in ptep_get()
  mm/gup: add fast-GUP specific lockless PTE helpers
  riscv: mm: avoid Svnapot A/D aggregation in fast-GUP
  arm64: mm: avoid contpte A/D aggregation in fast-GUP
  riscv/mm: remove redundant TLB flush in napotpte_convert
  riscv/mm: optimize mprotect for Svnapot mappings
  riscv: mm: Request large exec folios for Svnapot

 arch/arm64/include/asm/pgtable.h |  25 +-
 arch/riscv/include/asm/kfence.h  |   4 +-
 arch/riscv/include/asm/pgtable.h | 480 +++++++++++++++++-
 arch/riscv/kernel/efi.c          |   4 +-
 arch/riscv/kernel/hibernate.c    |   3 +-
 arch/riscv/kvm/gstage.c          |  25 +-
 arch/riscv/kvm/mmu.c             |   4 +-
 arch/riscv/mm/Makefile           |   1 +
 arch/riscv/mm/contpte.c          | 804 +++++++++++++++++++++++++++++++
 arch/riscv/mm/fault.c            |   4 +-
 arch/riscv/mm/hugetlbpage.c      | 135 ++++--
 arch/riscv/mm/init.c             |   8 +-
 arch/riscv/mm/kasan_init.c       |  16 +-
 arch/riscv/mm/pageattr.c         |  12 +-
 arch/riscv/mm/pgtable.c          |  52 +-
 include/linux/pgtable.h          |  71 ++-
 kernel/events/core.c             |   2 +-
 mm/gup.c                         |   6 +-
 mm/internal.h                    |  39 +-
 mm/mincore.c                     |   2 +-
 mm/mremap.c                      |   2 +-
 21 files changed, 1542 insertions(+), 157 deletions(-)
 create mode 100644 arch/riscv/mm/contpte.c


base-commit: b8809969e1d7a591e0f49dd464a5d04b3cf02ab1
-- 
2.39.5