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

[Paolo Bonzini]

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