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

Christian Zigotzky
2026-02-14T14:05:39Z

Hello,

KVM PR and KVM HV do not work if the kernel was compiled with PREEMPT.

The entire FSL Cyrus+ board freezes when using KVM HV with PREEMPT.

The guest kernel doesn't boot if we use KVM PR with a PREEMPT kernel on
the PA Semi Nemo board.

We were previously able to disable PREEMPT in the kernel configuration,
but the latest git kernels now enable it by default and it is no longer
possible to disable it.

I created a patch for disabling PREEMPT today. [1]

Is it possible to let us decide whether to activate PREEMPT or not?

Thanks in advance,

Christian

[1]
https://raw.githubusercontent.com/chzigotzky/kernels/a74fa6179eaeafcea7ad89f0e61c30ace038daf2/patches/X1000/Kconfig.preempt.patch
[2] Bug report: https://github.com/chzigotzky/kernels/issues/19