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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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.

~Andrew

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