linux-kernel - Re: [PATCH 2/4] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 1 Dec 2016 10:02:11 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
        One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Brian Gerst <brgerst@...il.com>,
        Matthew Whitehead <tedheadster@...il.com>,
        Henrique de Moraes Holschuh <hmh@....eng.br>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 2/4] Revert "x86/boot: Fail the boot if !M486 and CPUID
 is missing"

On Thu, Dec 01, 2016 at 06:53:50AM +0100, Peter Zijlstra wrote:
> On Wed, Nov 30, 2016 at 12:34:53PM -0800, Andy Lutomirski wrote:
> > This reverts commit ed68d7e9b9cfb64f3045ffbcb108df03c09a0f98.
> > 
> > The patch wasn't quite correct -- there are non-Intel (and hence
> > non-486) CPUs that we support that don't have CPUID.  Since we no
> > longer require CPUID for sync_core(), just revert the patch.
>
> Might be useful to enumerate which special parts these are.

Right, and since we test for CPUID support at early boot, I think we
should use the X86_FEATURE_CPUID aspect from what I proposed earlier:

https://lkml.kernel.org/r/20161120111917.pw3alolx4fksfwbv@pd.tnic

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.