Subject: Re: [PATCH v2] x86/smpboot: Make logical package management more
 robust
To: Thomas Gleixner <tglx@linutronix.de>
References: <alpine.DEB.2.20.1612081001230.3400@nanos>
 <alpine.DEB.2.20.1612092305060.3612@nanos>
 <8aa33de4-db18-759b-d2cb-0e25d5ab9d88@oracle.com>
 <730d61ff-ff1e-df80-3446-7fceb25a6d63@oracle.com>
 <alpine.DEB.2.20.1612102004210.18281@nanos>
 <alpine.DEB.2.20.1612102012060.18281@nanos>
 <60e7a807-27fb-f666-270a-9512804deae8@oracle.com>
 <alpine.DEB.2.20.1612121102260.3429@nanos>
Cc: LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>,
        "Charles (Chas) Williams" <ciwillia@brocade.com>,
        "M. Vefa Bicakci" <m.v.b@runbox.com>,
        Alok Kataria <akataria@vmware.com>,
        xen-devel <xen-devel@lists.xen.org>,
        =?UTF-8?Q?Juergen_Gro=c3=9f?= <jgross@suse.com>
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Message-ID: <4b04a0a1-205f-3c6e-50c1-ad3f79d3d89a@oracle.com>
Date: Mon, 12 Dec 2016 14:07:54 -0500
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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@suse.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: stable@vger.kernel.org

For Xen:

Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.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