linux-kernel - Re: [PATCH 10/16] x86/mm/pti: Populate valid user pud entries

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Message-ID: <20180116194112.GD28161@8bytes.org>
Date:   Tue, 16 Jan 2018 20:41:12 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Brian Gerst <brgerst@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Eduardo Valentin <eduval@...zon.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Will Deacon <will.deacon@....com>, aliguori@...zon.com,
        daniel.gruss@...k.tugraz.at, hughd@...gle.com, keescook@...gle.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Waiman Long <llong@...hat.com>, jroedel@...e.de
Subject: Re: [PATCH 10/16] x86/mm/pti: Populate valid user pud entries

On Tue, Jan 16, 2018 at 10:06:48AM -0800, Dave Hansen wrote:
> On 01/16/2018 08:36 AM, Joerg Roedel wrote:
> > 
> > In PAE page-tables at the top-level most bits we usually set
> > with _KERNPG_TABLE are reserved, resulting in a #GP when
> > they are loaded by the processor.
> 
> Can you save me the trip to the SDM and remind me which bits actually
> cause trouble here?

Everything besides PRESENT, PCD, PWT and the actual physical address, so
RW, and NX for example cause a #GP.


	Joerg