Re: [PATCH 0/2] KVM: PPC: BookE: Fix boot hang on preemptible kernels

[Shrikanth Hegde]

Hi.

On 9/28/26 4:34 PM, Shrikanth Hegde wrote:
> Christian Zigotzky had reported that preemptible kernels don't boot on
> his FSL Cyrus+ board. The board freezes on running either full/lazy
> preemption and has been an issue for a while now.
>
> https://lore.kernel.org/all/b897b0fd-90f2-4215-bcd4-3714e497d773@xxxxxxxxxxx/#t
>
> After 7.0, there is only preempt=full/lazy which removed the
> preempt=none/voluntary workaround used to mask the issue. There was
> challenge is getting the console logs which made the fixes difficult since
> one couldn't know where the issue is.
>
> Thanks to Michal for helping in getting the logs. That pointed at few
> places where the issue could be. This series is an attempt at fixing
> those.
>
> Christian, KVM team,
> Please *test* the patches.
>
> Shrikanth Hegde (2):
>    KVM: PPC: BookE: Disable preemption before loading guest FP and
>      Altivec
>    KVM: PPC: Replay pending interrupts before entering the guest
>
>   arch/powerpc/kvm/booke.c   |  9 ++++++++-
>   arch/powerpc/kvm/powerpc.c | 13 +++++++++++++
>   2 files changed, 21 insertions(+), 1 deletion(-)

All the suggested changes makes sense. I will plan to send out version soon.
Hopefully mid next week.

1. Re-order in below way.
	kvmppc_load_guest_fp(vcpu);
	kvmppc_load_guest_altivec(vcpu);
	kvmppc_fix_ee_before_entry();

2. Define a common helper. I am thinking to name it as ppc_hard_irq_disable().
   Since suggestion was also to be used in the entry code.
   Other names i could think of are local_hard_irq_disable,
   arch_hard_irq_disable, local_irq_disable_hard.