linux-kernel - Re: [PATCH v2] x86/smpboot: Make logical package management more robust

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:   Mon, 12 Dec 2016 14:07:54 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        "Charles (Chas) Williams" <ciwillia@...cade.com>,
        "M. Vefa Bicakci" <m.v.b@...box.com>,
        Alok Kataria <akataria@...are.com>,
        xen-devel <xen-devel@...ts.xen.org>,
        Juergen Groß <jgross@...e.com>
Subject: Re: [PATCH v2] x86/smpboot: Make logical package management more
 robust

On 12/12/2016 05:04 AM, Thomas Gleixner wrote:
> The logical package management has several issues:
>
>  - The APIC ids provided by ACPI are not required to be the same as the
>    initial APIC id which can be retrieved by CPUID. The APIC ids provided
>    by ACPI are those which are written by the BIOS into the APIC. The
>    initial id is set by hardware and can not be changed. The hardware
>    provided ids contain the real hardware package information.
>
>    Especially AMD sets the effective APIC id different from the hardware id
>    as they need to reserve space for the IOAPIC ids starting at id 0.
>
>    As a consequence those machines trigger the currently active firmware
>    bug printouts in dmesg, These are obviously wrong.
>
>  - Virtual machines have their own interesting of enumerating APICs and
>    packages which are not reliably covered by the current implementation.
>
> The sizing of the mapping array has been tweaked to be generously large to
> handle systems which provide a wrong core count when HT is disabled so the
> whole magic which checks for space in the physical hotplug case is not
> needed anymore.
>
> Simplify the whole machinery and do the mapping when the CPU starts and the
> CPUID derived physical package information is available. This solves the
> observed problems on AMD machines and works for the virtualization issues
> as well.
>
> Remove the extra call from XEN cpu bringup code as it is not longer
> required.
>
> Fixes: d49597fd3bc7 ("x86/cpu: Deal with broken firmware (VMWare/XEN)")
> Reported-and-tested-by: Borislav Petkov <bp@...e.de>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: stable@...r.kernel.org

For Xen:

Tested-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>

(Note that we still have
    [Firmware Bug]: CPU13: APIC id mismatch. Firmware: 0 APIC: d
but that will be fixed in Xen code.)

-boris