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: <20181106184519.GA16391@zn.tnic>
Date:   Tue, 6 Nov 2018 19:45:19 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Masayoshi Mizuma <msys.mizuma@...il.com>
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 09:40:51AM -0400, Masayoshi Mizuma wrote:
> 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?

Ok, having swapped the whole thing back into my brain, forget what I
said earlier today.

Didn't we talk about passing info with setup_data to the later kernel
stage? You even had a patch:

https://lkml.kernel.org/r/20181022154204.kagmdb55jtoez4ca@gabell

So what is that "idea" again about adding SRAT parsing code to
arch/x86/mm/kaslr.c?!?!

The intent of passing info with setup_data is to *avoid* parsing SRAT
yet another time and duplicating that code one more time.

IOW:

* The first place that needs SRAT parsing, does the parsing - i.e., the
compressed stage.

* Later stages get information passed to them with setup_data. No second
parsing.

Ok?

-- 
Regards/Gruss,
    Boris.

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