Re: [Qemu-devel] [RFC] create a single workqueue for each vm to update vm irq routing table

Paolo Bonzini
2013-11-26T16:28:36Z

Il 26/11/2013 17:24, Gleb Natapov ha scritto:
>> VCPU writes to routing table
>> e = entry from IRQ routing table
>> kvm_irq_routing_update(kvm, new);
>> VCPU resumes execution
>> kvm_set_msi_irq(e, &irq);
>> kvm_irq_delivery_to_apic_fast();
>>
>> where the entry is stale but the VCPU has already resumed execution.
>
> So how is it different from what we have now:
>
> disable_irq()
> VCPU writes to routing table
> e = entry from IRQ routing table
> kvm_set_msi_irq(e, &irq);
> kvm_irq_delivery_to_apic_fast();
> kvm_irq_routing_update(kvm, new);
> synchronize_rcu()
> VCPU resumes execution
> enable_irq()
> receive stale irq

Adding a "disable/enable IRQs" looks like a relatively big change. But
perhaps it's not for some reason I'm missing.

Paolo