linux-kernel - Re: [PATCH v4] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges

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]

Date:   Fri, 22 Nov 2019 12:30:52 +0100
From:   Karol Herbst <kherbst@...hat.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Mika Westerberg <mika.westerberg@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Lyude Paul <lyude@...hat.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        nouveau <nouveau@...ts.freedesktop.org>,
        Dave Airlie <airlied@...il.com>,
        Mario Limonciello <Mario.Limonciello@...l.com>
Subject: Re: [PATCH v4] pci: prevent putting nvidia GPUs into lower device
 states on certain intel bridges

On Fri, Nov 22, 2019 at 10:07 AM Rafael J. Wysocki <rafael@...nel.org> wrote:
>
> On Fri, Nov 22, 2019 at 1:13 AM Karol Herbst <kherbst@...hat.com> wrote:
> >
> > so while trying to test with d3cold disabled, I noticed that I run
> > into the exact same error.
>
> Does this mean that you disabled d3cold on the GPU via sysfs (the
> "d3cold_allowed" attribute was 0) and the original problem still
> occurred in that configuration?
>

yes. In my previous testing I was poking into the PCI registers of the
bridge controller and the GPU directly and that never caused any
issues as long as I limited it to putting the devices into D3hot.

> > And I verified that the
> > \_SB.PCI0.PEG0.PG00._STA returns 1, which indicates it should still be
> > turned on.
>
> I don't really understand this comment, so can you explain it a bit to
> me, please?
>

that's the ACPI method to fetch the "status" of the power resource, it
should return 0 when the device was powered off (the GPU) and 1
otherwise.