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

On 17/02/26 11:17 Madhavan Srinivasan wrote:

On 2/17/26 3:14 PM, Christian Zigotzky wrote:

quoted

On 17/02/26 10:03, Shrikanth Hegde wrote:

quoted

On 2/17/26 2:22 PM, Christian Zigotzky wrote:

quoted

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