Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934273AbcKJP34 convert rfc822-to-8bit (ORCPT ); Thu, 10 Nov 2016 10:29:56 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:33167 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933905AbcKJP3y (ORCPT ); Thu, 10 Nov 2016 10:29:54 -0500 Subject: Re: [PATCH] x86/cpuid: Deal with broken firmware once more To: "Charles (Chas) Williams" , Thomas Gleixner , "M. Vefa Bicakci" References: <20161102122557.qs4rl6mb7n7l7j7p@linutronix.de> <24e69019-60d0-29e7-e31f-c6f00f9ed98a@brocade.com> <58e229e2-91f4-a97f-1b9f-089f48ef994a@brocade.com> <86609338-2b45-ed7e-fb07-99421e43a2f1@brocade.com> <49fe8cc5-0f0f-6cac-7a5c-803e81f5667d@runbox.com> Cc: Sebastian Andrzej Siewior , "x86@kernel.org" , LKML , Peter Zijlstra , Borislav Petkov , David Vrabel , Juergen Gross From: Boris Ostrovsky Message-ID: Date: Thu, 10 Nov 2016 10:31:20 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8BIT X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2081 Lines: 57 On 11/10/2016 10:05 AM, Charles (Chas) Williams wrote: > > > On 11/10/2016 09:02 AM, Boris Ostrovsky wrote: >> On 11/10/2016 06:13 AM, Thomas Gleixner wrote: >>> On Thu, 10 Nov 2016, M. Vefa Bicakci wrote: >>> >>>> I have found that your patch unfortunately does not improve the >>>> situation >>>> for me. Here is an excerpt obtained from the dmesg of a kernel >>>> compiled >>>> with this patch *as well as* Sebastian's patch: >>>> [ 0.002561] CPU: Physical Processor ID: 0 >>>> [ 0.002566] CPU: Processor Core ID: 0 >>>> [ 0.002572] [Firmware Bug]: CPU0: APIC id mismatch. Firmware: >>>> ffff CPUID: 2 >>> So apic->cpu_present_to_apicid() gives us a completely bogus APIC id >>> which >>> translates to a bogus package id. And looking at the XEN code: >>> >>> xen_pv_apic.cpu_present_to_apicid = xen_cpu_present_to_apicid, >>> >>> and xen_cpu_present_to_apicid does: >>> >>> static int xen_cpu_present_to_apicid(int cpu) >>> { >>> if (cpu_present(cpu)) >>> return xen_get_apic_id(xen_apic_read(APIC_ID)); >>> else >>> return BAD_APICID; >>> } >>> >>> So independent of which present CPU we query we get just some random >>> information, in the above case we get BAD_APICID from >>> xen_apic_read() not >>> from the else path as this CPU _IS_ present. >>> >>> What's so wrong with storing the fricking firmware supplied APICid as >>> everybody else does and report it back when queried? >> >> By firmware you mean ACPI? It is most likely not available to PV guests. >> How about returning cpu_data(cpu).initial_apicid? >> >> And what was the original problem? > > The original issue I found was that VMware was returning a different set > of APIC id's in the ACPI tables than what it advertised on the CPU's. > > http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1266716.html For Xen, we recently added a6a198bc60e6 ("xen/x86: Update topology map for PV VCPUs") to at least temporarily work around some topology map problems that PV guests have with RAPL (which I think is what Vefa's problem was). -boris