linux-kernel - Re: Yet another KPTI regression with 4.14.x series in a VM

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Date:   Sat, 13 Jan 2018 14:51:40 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Laura Abbott <labbott@...hat.com>, X86 ML <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>
Subject: Re: Yet another KPTI regression with 4.14.x series in a VM

On Sat, Jan 13, 2018 at 01:50:55PM +0100, Thomas Gleixner wrote:
>  2:0 Ignored
>    3 PWT
>    4 PCD

Btw, those last two are "(implies PCD=PWT=0)" according to
http://www.sandpile.org/x86/crx.htm with PCID. I was wondering recently
what happens with those bits when PCID is enabled and CR3[11:0] is the
ASID. I couldn't find it in the SDM.

And it kinda makes sense, PCD=1b is probably only for testing some
hardware crud and not really sensible for normal production.

-- 
Regards/Gruss,
    Boris.

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