[FSL P50x0] KVM HV doesn't work anymore

[Christian Zigotzky]

> On 17. May 2021, at 11:43, Christian Zigotzky <chzigotzky at xenosoft.de> wrote:
> 
> On 17 May 2021 at 09:42am, Nicholas Piggin wrote:
>> Excerpts from Christian Zigotzky's message of May 15, 2021 11:46 pm:
>>> On 15 May 2021 at 12:08pm Christophe Leroy wrote:
>>>> 
>>>>> Le 15/05/2021 à 11:48, Christian Zigotzky a écrit :
>>>>>> Hi All,
>>>>>> 
>>>>>> I bisected today [1] and the bisecting itself was OK but the
>>>>>> reverting of the bad commit doesn't solve the issue. Do you have an
>>>>>> idea which commit could be resposible for this issue? Maybe the
>>>>>> bisecting wasn't successful. I will look in the kernel git log. Maybe
>>>>>> there is a commit that affected KVM HV on FSL P50x0 machines.
>>>>> If the uImage doesn't load, it may be because of the size of uImage.
>>>>> 
>>>>> See https://github.com/linuxppc/issues/issues/208
>>>>> 
>>>>> Is there a significant size difference with and without KVM HV ?
>>>>> 
>>>>> Maybe you can try to remove another option to reduce the size of the
>>>>> uImage.
>>> I tried it but it doesn't solve the issue. The uImage works without KVM
>>> HV in a virtual e5500 QEMU machine.
>> Any more progress with this? I would say that bisect might have just
>> been a bit unstable and maybe by chance some things did not crash so
>> it's pointing to the wrong patch.
>> 
>> Upstream merge of powerpc-5.13-1 was good and powerpc-5.13-2 was bad?
>> 
>> Between that looks like some KVM MMU rework. You could try the patch
>> before this one b1c5356e873c ("KVM: PPC: Convert to the gfn-based MMU
>> notifier callbacks"). That won't revert cleanly so just try run the
>> tree at that point. If it works, test the patch and see if it fails.
>> 
>> Thanks,
>> Nick
> Hi Nick,
> 
> Thanks a lot for your answer. Yes, there is a little bit of progress. The RC2 of kernel 5.13 successfully boots with -smp 3 in a virtual e5500 QEMU machine.
> -smp 4 doesn't work anymore since the PowerPC updates 5.13-2. I used -smp 4 before 5.13 because my FSL P5040 machine has 4 cores.
> 
> Could you please post a patch for reverting the commit before b1c5356e873c ("KVM: PPC: Convert to the gfn-based MMU notifier callbacks")?
> 
> Thanks in advance,
> 
> Christian
> 
> 
For me it is ok to work with -smp 1, 2, and 3 but I am curious why -smp 4 doesn’t work.

-Christian