linux-kernel - Re: [RFC PATCH V2 11/11] x86: tsc: avoid system instability in hibernation

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]

Message-ID: <CAJZ5v0jv+5aLY3N4wFSitu61o9S8tJWEWGGn1Xyw-P82_TwFdQ@mail.gmail.com>
Date:   Mon, 13 Jan 2020 22:50:59 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Singh, Balbir" <sblbir@...zon.com>,
        "Valentin, Eduardo" <eduval@...zon.com>,
        "boris.ostrovsky@...cle.com" <boris.ostrovsky@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Agarwal, Anchal" <anchalag@...zon.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "sstabellini@...nel.org" <sstabellini@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "Woodhouse@...-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com" 
        <Woodhouse@...-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "jgross@...e.com" <jgross@...e.com>, "pavel@....cz" <pavel@....cz>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "x86@...nel.org" <x86@...nel.org>,
        "roger.pau@...rix.com" <roger.pau@...rix.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "Kamata, Munehisa" <kamatam@...zon.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "konrad.wilk@...cle.co" <konrad.wilk@...cle.co>,
        "len.brown@...el.com" <len.brown@...el.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "fllinden@...ozn.com" <fllinden@...ozn.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [RFC PATCH V2 11/11] x86: tsc: avoid system instability in hibernation

On Mon, Jan 13, 2020 at 1:43 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Mon, Jan 13, 2020 at 11:43:18AM +0000, Singh, Balbir wrote:
> > For your original comment, just wanted to clarify the following:
> >
> > 1. After hibernation, the machine can be resumed on a different but compatible
> > host (these are VM images hibernated)
> > 2. This means the clock between host1 and host2 can/will be different
> >
> > In your comments are you making the assumption that the host(s) is/are the
> > same? Just checking the assumptions being made and being on the same page with
> > them.
>
> I would expect this to be the same problem we have as regular suspend,
> after power off the TSC will have been reset, so resume will have to
> somehow bridge that gap. I've no idea if/how it does that.

In general, this is done by timekeeping_resume() and the only special
thing done for the TSC appears to be the tsc_verify_tsc_adjust(true)
call in tsc_resume().

> I remember some BIOSes had crazy TSC ideas for suspend2ram, and we grew
> tsc_restore_sched_clock_state() for it.
>
> Playing crazy games like what you're doing just isn't it though.

Right.