From: "M. Vefa Bicakci" <m.v.b@runbox.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "Charles (Chas) Williams" <ciwillia@Brocade.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
David Vrabel <david.vrabel@citrix.com>,
Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH] x86/cpuid: Deal with broken firmware once more
Date: Sun, 13 Nov 2016 01:05:19 +0300 [thread overview]
Message-ID: <f622cd63-6af5-af71-9a5c-b6c71d269dfa@runbox.com> (raw)
In-Reply-To: <cc8425f3-23df-a9e7-bc01-db6b529f96e5@oracle.com>
On 11/10/2016 06:31 PM, Boris Ostrovsky wrote:
> 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).
Hello Boris,
(Sorry for the delay!)
It appears that the problem is a bit different compared to the one
corrected by a6a198bc60e6, because my kernel tree -- based on 4.8.6 --
already includes the -stable backport of that commit, i.e.
88540ad0820ddfb05626e0136c0e5a79cea85fd1
The patch I included in my previous e-mail (dated 2016-11-10) corrects
root cause of the issue I am having with 4.8.6. Sebastian's original
patch adding error checking to the RAPL module prevents the RAPL module
from causing a kernel oops without my patch.
The issue I am experiencing is caused by the boot-up code in the
'init_apic_mappings' function switching the APIC ops structure from
Xen's structure to a no-op structure by calling the 'apic_disable'
function. Please let me know if I can clarify or elaborate.
For the record, using 4.8.7 without my correction patch patch does not
rectify the issue at hand. 4.8.7 changes the call site of the
'init_apic_mapping' function, so I had thought that it could be helpful.
Thank you,
Vefa
next prev parent reply other threads:[~2016-11-12 22:06 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-02 12:25 [RFC PATCH] perf/x86/intel/rapl: avoid access unallocate memory Sebastian Andrzej Siewior
2016-11-02 22:47 ` Charles (Chas) Williams
2016-11-03 17:47 ` Sebastian Andrzej Siewior
2016-11-04 12:20 ` Charles (Chas) Williams
2016-11-04 18:03 ` Sebastian Andrzej Siewior
2016-11-04 20:42 ` Charles (Chas) Williams
2016-11-04 20:57 ` Sebastian Andrzej Siewior
2016-11-07 16:19 ` Thomas Gleixner
2016-11-07 16:59 ` Charles (Chas) Williams
2016-11-07 20:20 ` Thomas Gleixner
2016-11-08 14:20 ` Charles (Chas) Williams
2016-11-08 14:31 ` Thomas Gleixner
2016-11-08 14:57 ` Charles (Chas) Williams
2016-11-08 16:22 ` Thomas Gleixner
2016-11-09 15:35 ` [PATCH] x86/cpuid: Deal with broken firmware once more Thomas Gleixner
2016-11-09 15:37 ` Thomas Gleixner
2016-11-09 16:03 ` Peter Zijlstra
2016-11-09 16:34 ` Charles (Chas) Williams
2016-11-09 18:37 ` Thomas Gleixner
2016-11-09 18:15 ` Charles (Chas) Williams
2016-11-09 20:27 ` [tip:x86/urgent] x86/cpu: Deal with broken firmware (VMWare/XEN) tip-bot for Thomas Gleixner
2016-11-11 5:49 ` Alok Kataria
2016-11-10 3:57 ` [PATCH] x86/cpuid: Deal with broken firmware once more M. Vefa Bicakci
2016-11-10 10:50 ` Charles (Chas) Williams
2016-11-10 11:14 ` Thomas Gleixner
2016-11-12 22:05 ` M. Vefa Bicakci
2016-11-10 11:13 ` Thomas Gleixner
2016-11-10 11:39 ` Peter Zijlstra
2016-11-10 14:02 ` Boris Ostrovsky
2016-11-10 15:05 ` Charles (Chas) Williams
2016-11-10 15:31 ` Boris Ostrovsky
2016-11-10 15:54 ` Sebastian Andrzej Siewior
2016-11-10 17:15 ` Thomas Gleixner
2016-11-12 22:05 ` M. Vefa Bicakci [this message]
2016-11-13 18:04 ` Boris Ostrovsky
2016-11-13 23:42 ` M. Vefa Bicakci
2016-11-15 1:21 ` Boris Ostrovsky
2016-11-18 11:16 ` Thomas Gleixner
2016-11-18 14:22 ` Boris Ostrovsky
2016-11-10 15:12 ` Thomas Gleixner
2016-11-10 15:38 ` Boris Ostrovsky
2016-11-10 17:13 ` Thomas Gleixner
2016-11-10 18:01 ` Boris Ostrovsky
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