linux-kernel - Re: [v4.17-rcx] Lost IBPB, IBRS_FW support for spectre

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Date:   Sat, 5 May 2018 11:47:53 +0200
From:   Jörg Otte <jrg.otte@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [v4.17-rcx] Lost IBPB, IBRS_FW support for spectre_v2 mitigation.

2018-05-04 18:18 GMT+02:00 Borislav Petkov <bp@...en8.de>:
> On Wed, May 02, 2018 at 02:20:52PM +0200, Thomas Gleixner wrote:
>> Thanks for confirming. Still need to find a way which is less fragile, but
>> that's probably too much of churn for rc4....
>>
>> At least I know exactly what's happening, so I can write a better changelog.
>>
>> Thanks for testing!
>
> Jörg, can you pls also test this one ontop of Thomas' patch to make
> sure it doesn't break your box.
>
> Thx.
>
> ---
> From 6857c2ac8e31f4f9b350cfad4f6b6eb831bf57f1 Mon Sep 17 00:00:00 2001
> From: Borislav Petkov <bp@...e.de>
> Date: Wed, 2 May 2018 18:15:14 +0200
> Subject: [PATCH] x86/CPU: Use synthetic bits for IBRS/IBPB/STIBP
>
> Intel and AMD have different CPUID bits for those so use synthetic bits
> which get set on the respective vendor in init_speculation_control(). So
> that debacles like the commit message of
>
>   c65732e4f721 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")
>

Patch doesn't hurt me. For me it´s ok.

Thanks, Jörg