[Linux PPC] KVM PR and KVM HV do not work if the kernel was compiled with PREEMPT

[Christian Zigotzky]

On 17/02/26 11:17 Madhavan Srinivasan wrote:
>
> On 2/17/26 3:14 PM, Christian Zigotzky wrote:
>> On 17/02/26 10:03, Shrikanth Hegde wrote:
>>>
>>>
>>> On 2/17/26 2:22 PM, Christian Zigotzky wrote:
>>>> Hi,
>>>>
>>>> Thank you for your patch. I tested the latest git kernel with your 
>>>> patch today. Unfortunately the system freezes while booting the VM 
>>>> with KVM HV.
>>>>
>>>> Cheers,
>>>> Christian
>>>>
>>>>
>>> Would it be possible to share the console log or boot log of KVM to the
>>> point it freezes?
>>
>> Unfortunately there aren't any error messages.
>>
>> I also tried it with:
>>
>> gdb --args qemu-system-ppc64 -M ppce500 -cpu e5500 -m 1024 -kernel 
>> uImage-7.0-preempt -drive 
>> format=raw,file=void-live-powerpc-20230317-updated2.img,index=0,if=virtio 
>> -netdev user,id=mynet0 -device virtio-net,netdev=mynet0 -append "rw 
>> root=/dev/vda" -device virtio-gpu-pci -device virtio-mouse-pci 
>> -device virtio-keyboard-pci -enable-kvm -smp 4
>>
>> and with gdb in the guest:
>>
>> qemu-system-ppc64 -s -S -M ppce500 -cpu e5500 -m 1024 -kernel 
>> uImage-7.0-preempt -drive 
>> format=raw,file=void-live-powerpc-20230317-updated2.img,index=0,if=virtio 
>> -netdev user,id=mynet0 -device virtio-net,netdev=mynet0 -append "rw 
>> root=/dev/vda" -device virtio-gpu-pci -device virtio-mouse-pci 
>> -device virtio-keyboard-pci -enable-kvm -smp 4
>>
>> The system freezed without any error messages.
> can you please share the config.
> I tried kvm-hv in my power8/power9 and seems to boot fine without any 
> issues with today's upstream
> Maddy
Here are the configs.

With PREEMPT: 
https://github.com/chzigotzky/kernels/blob/d50d259ca63dd2b3b9a9eaabc82e5cc69c8cc9f0/configs/e5500_defconfig

Without PREEMPT: 
https://github.com/chzigotzky/kernels/blob/main/configs/e5500_defconfig

- Christian