linux-kernel - RE: [patch v2 21/38] x86/cpu: Provide cpu_init/parse

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Date:   Mon, 31 Jul 2023 22:41:27 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     "x86@...nel.org" <x86@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Dick Kennedy <dick.kennedy@...adcom.com>,
        James Smart <james.smart@...adcom.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Huang Rui <ray.huang@....com>, Juergen Gross <jgross@...e.com>,
        Steve Wahl <steve.wahl@....com>,
        Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Russ Anderson <russ.anderson@....com>
Subject: RE: [patch v2 21/38] x86/cpu: Provide cpu_init/parse_topology()

On Mon, Jul 31 2023 at 16:25, Michael Kelley wrote:
> From: Thomas Gleixner <tglx@...utronix.de> Sent: Monday, July 31, 2023 5:35 AM
>> Define bogus. MADT is the primary source of information because that's
>> how we know how many CPUs (APICs) are there and what their APIC ID is
>> which we can use to wake them up. So there is a reasonable expectation
>> that this information is consistent with the rest of the system.
>
> Commit d49597fd3bc7 "x86/cpu: Deal with broken firmware (VMWare/Xen)"
> mentions VMware and XEN implementations that violate the spec.  The
> commit is from late 2016.  Have these bad systems aged out and no longer
> need accommodation?

They do, but this commit explicitely uses the MADT/real APIC ID value:

     c->initial_apicid = apicid;

So the new mechanics are accomodating for those, right?

Thanks,

        tglx