On Thu, 2020-11-26 at 19:00 +0100, Paolo Bonzini wrote:
>   static int kvm_vcpu_ready_for_interrupt_injection(struct kvm_vcpu
> *vcpu)
>   {
> +       WARN_ON(pic_in_kernel(vcpu->kvm));
> +

But what if I *want* to inject Xen event channel interrupts while the
actual PIC is in the kernel? :)

Not that I'll have to once the kernel is fixed and I can enable my
shiny new userspace PIC/PIT/IOAPIC code, I suppose.... 

>         return kvm_arch_interrupt_allowed(vcpu) &&
> -               !kvm_cpu_has_interrupt(vcpu) &&
>                 !kvm_event_needs_reinjection(vcpu) &&
> -               kvm_cpu_accept_dm_intr(vcpu);
> +               (!lapic_in_kernel(vcpu)
> +                || (kvm_apic_accept_pic_intr(vcpu)
> +                    && !pending_userspace_extint(v));
>   }
> 

I'll give this version a spin...


static int kvm_vcpu_ready_for_interrupt_injection(struct kvm_vcpu *vcpu)
{
	return kvm_arch_interrupt_allowed(vcpu) &&
		!kvm_event_needs_reinjection(vcpu) &&
		(!lapic_in_kernel(vcpu)
		 || (kvm_apic_accept_pic_intr(vcpu)
		     && vcpu->arch.pending_external_vector == -1));
}