linux-kernel - Re: [PATCHv9 0/4] x86: 5-level related changes into decompression code

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Date:   Sun, 11 Feb 2018 12:37:08 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        Borislav Petkov <bp@...e.de>, Andi Kleen <ak@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv9 0/4] x86: 5-level related changes into decompression
 code


* Kirill A. Shutemov <kirill.shutemov@...ux.intel.com> wrote:

> These patcheset is a preparation for boot-time switching between paging
> modes. Please apply.
> 
> The first patch is pure cosmetic change: it gives file with KASLR helpers
> a proper name.
> 
> The last three patches bring support of booting into 5-level paging mode if
> a bootloader put the kernel above 4G.
> 
> Patch 2/4 Renames l5_paging_required() into paging_prepare() and change
> interface of the function.
> Patch 3/4 Handles allocation of space for trampoline and gets it prepared.
> Patch 4/4 Gets trampoline used.
> 
> v9:
>  - Patch 3 now saves and restores lowmem used for trampoline.
> 
>    There was report the patch causes issue on a machine. I suspect it's
>    BIOS issue that doesn't report proper bounds of usable lowmem.
> 
>    Restoring memory back to oringinal state makes problem go away.
> v8:
>  - Support switching from 5- to 4-level paging.
> v7:
>  - Fix booting when 5-level paging is enabled before handing off boot to
>    the kernel, like in kexec() case.
> 
> Kirill A. Shutemov (4):
>   x86/boot/compressed/64: Rename pagetable.c to kaslr_64.c
>   x86/boot/compressed/64: Introduce paging_prepare()
>   x86/boot/compressed/64: Prepare trampoline memory
>   x86/boot/compressed/64: Handle 5-level paging boot if kernel is above
>     4G
> 
>  arch/x86/boot/compressed/Makefile                  |   2 +-
>  arch/x86/boot/compressed/head_64.S                 | 178 ++++++++++++++-------
>  .../boot/compressed/{pagetable.c => kaslr_64.c}    |   0
>  arch/x86/boot/compressed/pgtable.h                 |  18 +++
>  arch/x86/boot/compressed/pgtable_64.c              | 100 ++++++++++--
>  5 files changed, 232 insertions(+), 66 deletions(-)
>  rename arch/x86/boot/compressed/{pagetable.c => kaslr_64.c} (100%)
>  create mode 100644 arch/x86/boot/compressed/pgtable.h

Ok, this series looks pretty good - I've applied it to tip:x86/boot for an 
eventual 4.17 merge and will push it out if it passes local testing.

Thanks,

	Ingo