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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 02/03/17 19:28, Sander Eikelenboom wrote:
> On 02/03/17 20:17, Andrew Cooper wrote:
>> On 02/03/17 19:15, Boris Ostrovsky wrote:
>>> 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;
> This doesn't boot.
> --
> Sander

Ok.  So something in dom0 is taking extreme objection to the APIC IDs.

As a stopgap fix, this can be moved back to being HVM only. (And I am
going to have even more $FUN than I was originally planning, fixing the
topology reporting)

~Andrew

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