linux-kernel - Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory

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Date:   Wed, 10 Oct 2018 15:44:44 -0400
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Baoquan He <bhe@...hat.com>
Cc:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Chao Fan <fanc.fnst@...fujitsu.com>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-efi@...r.kernel.org,
        linux-acpi@...r.kernel.org, mingo@...hat.com, hpa@...or.com,
        keescook@...omium.org, rjw@...ysocki.net, lenb@...nel.org,
        ard.biesheuvel@...aro.org, indou.takao@...fujitsu.com,
        caoj.fnst@...fujitsu.com
Subject: Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr
 in immovable memory

On Wed, Oct 10, 2018 at 05:30:57PM +0800, Baoquan He wrote:
> On 10/10/18 at 11:19am, Borislav Petkov wrote:
> > On Wed, Oct 10, 2018 at 11:14:26AM +0200, Thomas Gleixner wrote:
> > > Yes, it's different, but if the SRAT information is available early, then
> > > the command line parameter can go away because then the required
> > > information for Masa's problem is available as well.
> > 
> > Exactly. And I'd prefer we delayed the command line parameter until we
> > figure out we really need it and not expose it to upstream and then
> > remove it shortly after.
> > 
> > So I'd suggest we move Masa's patches to a separate branch and not send
> > it up this round.
> 
> Yes, sounds more reasonable if we can reuse functions in Chao's patch 1/3
> to solve the padding issue.

Thanks for your comments! Yes, immovable_mem[num_immovable_mem] in Chao's
patch may be useful for calculating the padding size. If so, we don't
need the new kernel parameter. It's nice!

Do you happen to have ideas how we access immovable_mem[num_immovable_mem]
from arch/x86/mm/kaslr.c ? It is located to arch/x86/boot/compressed/*, so
I suppose it is not easy to access it... 
I would appreciate if you could give some advice.

Thanks!
Masa