[PATCH v12 0/3] riscv, mm: detect svnapot cpu support at runtime

[Qinglin Pan]

Svnapot is a RISC-V extension for marking contiguous 4K pages as a non-4K
page. This patch set is for using Svnapot in hugetlb fs and huge vmap.

This patchset adds a Kconfig item for using Svnapot in
"Platform type"->"SVNAPOT extension support". Its default value is on,
and people can set it off if they don't allow kernel to detect Svnapot
hardware support and leverage it.

Tested on:
  - qemu rv64 with "Svnapot support" off and svnapot=true.
  - qemu rv64 with "Svnapot support" on and svnapot=true.
  - qemu rv64 with "Svnapot support" off and svnapot=false.
  - qemu rv64 with "Svnapot support" on and svnapot=false.


Changes in v2:
  - detect Svnapot hardware support at boot time.
Changes in v3:
  - do linear mapping again if has_svnapot
Changes in v4:
  - fix some errors/warns reported by checkpatch.pl, thanks @Conor
Changes in v5:
  - modify code according to @Conor and @Heiko
Changes in v6:
  - use static key insead of alternative errata
Changes in v7:
  - add napot_cont_order for possible more napot order in the future
  - remove linear mapping related code from this patchset to another patch
  - refactor hugetlb code for svnapot according to thanks @Andrew @Conor
  - use tools/testing/selftests/vm/map_hugetlb as hugetlb testing program
  - support svnapot in huge vmap on newer for-next branch
Changes in v8:
  - fix compilation errors in rv32_defconfig
  - insert some lines of whitespace according to @Conor's suggestion
Changes in v9:
  - use alternative to avoid using static branches inside heavily used
    inline functions
  - change napot_cont_mask definition
  - post test_vmalloc modification about testing vmalloc_huge
Changes in v10:
  - fix some nits caught by @Andrew
  - collect Reviewed-by/Acked-by
  - add memory leak warning in KConfig text
  - replace test_vmalloc patch link with the standard one
Changes in v11:
  - add more detailed warning about HUGETLBFS and SVNAPOT in KConfig text
  - fix missing reverse-xmas tree
Changes in v12:
  - rebase on the new ISA extension API [1]

[1]https://lore.kernel.org/all/20230128172856.3814-5-jszhang@kernel.org/

Qinglin Pan (3):
  riscv: mm: modify pte format for Svnapot
  riscv: mm: support Svnapot in hugetlb page
  riscv: mm: support Svnapot in huge vmap

 arch/riscv/Kconfig                  |  21 +-
 arch/riscv/include/asm/hugetlb.h    |  34 +++-
 arch/riscv/include/asm/hwcap.h      |   9 +-
 arch/riscv/include/asm/page.h       |   5 -
 arch/riscv/include/asm/pgtable-64.h |  34 ++++
 arch/riscv/include/asm/pgtable.h    |  39 +++-
 arch/riscv/include/asm/vmalloc.h    |  61 +++++-
 arch/riscv/kernel/cpu.c             |   1 +
 arch/riscv/kernel/cpufeature.c      |   1 +
 arch/riscv/mm/hugetlbpage.c         | 301 ++++++++++++++++++++++++++++
 10 files changed, 493 insertions(+), 13 deletions(-)

-- 
2.39.1