Re: [Xen-devel] Xen-unstable: Bisected Host boot failure on AMD Phenom

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 03/02/2017 01:56 PM, Andrew Cooper wrote:
> On 02/03/17 18:51, Sander Eikelenboom wrote:
>> On 02/03/17 19:29, Andrew Cooper wrote:
>>> On 02/03/17 18:25, Sander Eikelenboom wrote:
>>>> On 02/03/17 18:38, Andrew Cooper wrote:
>>>>> On 02/03/17 17:29, Sander Eikelenboom wrote:
>>>>>> On 02/03/17 15:55, Andrew Cooper wrote:
>>>>>>> On 02/03/17 14:42, Sander Eikelenboom wrote:
>>>>>>>> Hi Andrew / Jan,
>>>>>>>>
>>>>>>>> While testing current xen-unstable staging i ran into my host 
>>>>>>>> rebooting in early kernel boot. 
>>>>>>>> Bisection has turned up:
>>>>>>>>     5cecf60f439e828f4bc0d2a368ced9a73b130cb7 is the first bad commit
>>>>>>>>     Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>>>>>>>     Date:   Fri Feb 17 17:10:50 2017 +0000
>>>>>>>>
>>>>>>>>     x86/cpuid: Handle leaf 0x1 in guest_cpuid()
>>>>>>>>
>>>>>>>> Hardware is a AMD phenom x6.
>>>>>>>> Below is the output of serial console of a failed boot.
>>>>>>> Hmm.  Sorry for breaking this (although my AMD servers are booting 
>>>>>>> fine).
>>>>>> No problem, it is the staging branch of the unstable tree anyway ;-)
>>>>>>
>>>>>>> It is unfortunately not entirely obvious what Linux is objecting to, and
>>>>>>> must be related to something visible in the emulated view.
>>>>>>>
>>>>>>> Does this delta make any difference?
>>>>>> Yes it does, boots fine with this patch applied, thanks !
>>>>> That is bad though. :s
>>>>>
>>>>> It means that something in dom0 has an aversion to my attempt to lie
>>>>> less about the topology.
>>>>>
>>>>> Do you mind checking whether
>>>>>
>>>>> res->b = cpuid_ebx(0x1) & 0xff00ffffu;
>>>>>
>>>>> causes is to break again?
>>>> Used that in the is_hardware_domain() case and it boots fine.
>>> Hmm - curious.  I am now even more confused.
>>>
>>> What about this?
>>>
>>> res->b = cpuid_ebx(0x1) & 0x00ffffffu;
>>>
>>> It will leave the APIC_ID field zeroed rather than feeding v->vcpu_id
>>> back into it.
>> Also boots fine.
> Right.  For my sanity, what about
>
> res->b = cpuid_ebx(0x1) & 0x00ffffffu;
> res->b |= (v->vcpu_id * 2) << 24;

FWIW, I booted a 2-node

  (XEN) CPU Vendor: AMD, Family 21 (0x15), Model 1 (0x1), Stepping 2
(raw 00600f12)

with Linux 4.10 and latest staging. (I thought perhaps my nightly missed
something because it's a single node)


-boris




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