linux-kernel - Re: [PATCH] powerpc: add support for folded p4d page tables

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Date:   Mon, 06 Jan 2020 14:31:41 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCH] powerpc: add support for folded p4d page tables

Mike Rapoport <rppt@...nel.org> writes:
> Any updates on this?

It's very ... big, and kind of intrusive.

It's not an improvement as far as the powerpc code's readability is
concerned. I assume the plan is that the 5-level hack can eventually be
removed and so this conversion is a prerequisite for that?

cheers

> On Mon, Dec 09, 2019 at 05:09:08PM +0200, Mike Rapoport wrote:
>> From: Mike Rapoport <rppt@...ux.ibm.com>
>> 
>> Implement primitives necessary for the 4th level folding, add walks of p4d
>> level where appropriate and replace 5level-fixup.h with pgtable-nop4d.h.
>> 
>> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
>> ---
>>  arch/powerpc/include/asm/book3s/32/pgtable.h  |  1 -
>>  arch/powerpc/include/asm/book3s/64/hash.h     |  4 +-
>>  arch/powerpc/include/asm/book3s/64/pgalloc.h  |  4 +-
>>  arch/powerpc/include/asm/book3s/64/pgtable.h  | 58 ++++++++++--------
>>  arch/powerpc/include/asm/book3s/64/radix.h    |  6 +-
>>  arch/powerpc/include/asm/nohash/32/pgtable.h  |  1 -
>>  arch/powerpc/include/asm/nohash/64/pgalloc.h  |  2 +-
>>  .../include/asm/nohash/64/pgtable-4k.h        | 32 +++++-----
>>  arch/powerpc/include/asm/nohash/64/pgtable.h  |  6 +-
>>  arch/powerpc/include/asm/pgtable.h            |  8 +++
>>  arch/powerpc/kvm/book3s_64_mmu_radix.c        | 59 ++++++++++++++++---
>>  arch/powerpc/lib/code-patching.c              |  7 ++-
>>  arch/powerpc/mm/book3s32/mmu.c                |  2 +-
>>  arch/powerpc/mm/book3s32/tlb.c                |  4 +-
>>  arch/powerpc/mm/book3s64/hash_pgtable.c       |  4 +-
>>  arch/powerpc/mm/book3s64/radix_pgtable.c      | 19 ++++--
>>  arch/powerpc/mm/book3s64/subpage_prot.c       |  6 +-
>>  arch/powerpc/mm/hugetlbpage.c                 | 28 +++++----
>>  arch/powerpc/mm/kasan/kasan_init_32.c         |  8 +--
>>  arch/powerpc/mm/mem.c                         |  4 +-
>>  arch/powerpc/mm/nohash/40x.c                  |  4 +-
>>  arch/powerpc/mm/nohash/book3e_pgtable.c       | 15 +++--
>>  arch/powerpc/mm/pgtable.c                     | 25 +++++++-
>>  arch/powerpc/mm/pgtable_32.c                  | 28 +++++----
>>  arch/powerpc/mm/pgtable_64.c                  | 10 ++--
>>  arch/powerpc/mm/ptdump/hashpagetable.c        | 20 ++++++-
>>  arch/powerpc/mm/ptdump/ptdump.c               | 22 ++++++-
>>  arch/powerpc/xmon/xmon.c                      | 17 +++++-
>>  28 files changed, 284 insertions(+), 120 deletions(-)