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

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Message-ID: <20181025134050.ggiir77ehntikbwg@gabell>
Date:   Thu, 25 Oct 2018 09:40:51 -0400
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Baoquan He <bhe@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Chao Fan <fanc.fnst@...fujitsu.com>,
        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 Thu, Oct 25, 2018 at 12:33:45PM +0200, Borislav Petkov wrote:
> On Mon, Oct 22, 2018 at 11:42:05AM -0400, Masayoshi Mizuma wrote:
> > I'm trying to store the SRAT info and pass it to kernel_randomize_memory(),
> > looks like add_e820ext()/parse_setup_data().
> > 
> > Is the approach useful only EFI environment? I'm not sure how I
> 
> Does it matter for non-EFI even?
> 
> I mean, you want this code only for your use case - when you have
> movable memory and you're doing kexec, yes?
> 
> And those machines are all EFI boxes I'd assume...

My actual use case is for EFI boxes, however, I think it's better to useful
for legacy BIOS as well because memory hot-plug affinity in SRAT and KASLR
are available on legacy BIOS.
Actually, we can create such environment in qemu.

I have another idea to solve this issue. Adding a SRAT parsing code
to arch/x86/mm/kaslr.c. It is useful for both EFI and BIOS and
also we don't need a new kernel parameter...
Dose the idea make sense?

Thanks,
Masa