linux-kernel - Re: [GIT PULL] x86/mm changes for v4.14: PCID support, 5-level paging support, Secure Memory Encryption support

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Message-Id: <50B32556-4ABD-424B-B01C-C314EEC33355@amacapital.net>
Date:   Tue, 5 Sep 2017 14:37:41 -0700
From:   Andy Lutomirski <luto@...capital.net>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [GIT PULL] x86/mm changes for v4.14: PCID support, 5-level paging support, Secure Memory Encryption support



> On Sep 5, 2017, at 2:17 PM, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> 
>> On Mon, Sep 4, 2017 at 2:31 AM, Ingo Molnar <mingo@...nel.org> wrote:
>> 
>> Please pull the latest ... git tree from:
>> 
>>   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git ...
> 
> Hmm. My laptop (XPS 13) doesn't resume any more. It suspends, but
> doesn't come back from resume.
> 

You could try booting with nopcid to rule out CR4 issues.  I can also imagine SME's very clever CR3 masking causing a problem.

Unfortunately, if it's a PCID problem involving wrong ordering of CR4 initialization, you might get lucky if you suspend with ASID 0 active, causing unfortunate bisection results.

I will test on my XPS 13 after lunch.

> I immediately assumed it was the power management pulls I just did,
> but then I started bisecting, and now it's actually pointing into the
> various x86 pulls I did yesterday instead.
> 
> Now, I'm reasonably early in my bisection (so literally "somewhere
> between the 'docs-next' and the 'x86-mm-for-linus' pull), and maybe
> the problem isn't even entirely repeatable and my bisection has
> already gone off the rails, but I thought I'd give at least an early
> heads-up about this thing.
> 
> I'll have more as it bisects deeper into the merge window, but it
> might be a while.
> 
>               Linus