Re: KVM devices assignment; PCIe AER?

[Etienne Martineau <etmartin101@gmail.com>]

On Wed, 27 Oct 2010, Alex Williamson wrote:
> KVM already has an internal IRQ ACK notifier (which is what current
> device assignment uses to do the same thing), it's just a matter of
> adding a callback that does a kvm_register_irq_ack_notifier that sends
> off the eventfd signal.  I've got this working and will probably send
> out the KVM patch this week.  For now the eventfd goes to userspace, but
> this is where I imagine we could steal some of the irqfd code to make
> VFIO consume the irqfd signal directly.  Thanks,

Thanks for the clarification. I must admit I was somewhat confuse about 
that irqfd mechanism until I realized that all it does is to consume an 
eventfd from kernel context (like you pointed out earlier...)
So from userspace I guess that it means that the same eventfd is going to be 
assigned to both VFIO and KVM right?

Going back to the original discussion, I think that devices assignment 
over VFIO is a great way to support PCIe AER for the assigned devices. I'm 
going to spend some time in that direction for sure. In the mean time I'll 
send some patches (shortly) that address the problem without any major 
surgery to the current implementation.

thanks,
-Etienne