On 09.01.20 14:47, Cornelia Huck wrote:
> On s390, we only allow userspace to create an in-kernel irqchip
> if it has first enabled the KVM_CAP_S390_IRQCHIP vm capability.
> Let's assume that a userspace that enabled that capability has
> created an irqchip as well.
>
> Fixes: 84223598778b ("KVM: s390: irq routing for adapter interrupts.")
> Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
> ---
>
> A more precise check would be to add a field in kvm_arch that tracks
> whether an irqchip has actually been created; not sure if that is
> really needed.
I think this is semantically wrong. We always have in-kernel irq handling.
It is actually not possible to not use it. So I understand where you are coming
from but this feels kind of wrong.
>
> Found while trying to hunt down QEMU crashes with kvm-irqchip=off;
> this is not sufficient, though. I *think* everything but irqfds
> should work without kvm-irqchip as well, but have not found the problem
> yet.
>
> ---
> arch/s390/kvm/irq.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/kvm/irq.h b/arch/s390/kvm/irq.h
> index 484608c71dd0..30e13d031379 100644
> --- a/arch/s390/kvm/irq.h
> +++ b/arch/s390/kvm/irq.h
> @@ -13,7 +13,7 @@
>
> static inline int irqchip_in_kernel(struct kvm *kvm)
> {
> - return 1;
> + return !!kvm->arch.use_irqchip;
> }
>
> #endif
>
