Re: [PATCH 10/10] KVM: MSI to INTx translate

[Avi Kivity <avi@redhat.com>]

Sheng Yang wrote:
> Yes, in theory, we got a little trouble, but not that much.
>
> The mechanism based on a assumption: every time guest got a interrupt, it 
> would deassert the interrupt source sooner or later. So we take the Ack action 
> as the same as deassert the IRQ line here (unmasked the IRQ).
>
> So the biggest known issue is, after guest got the interrupt, rather than 
> deassert it, guest driver took the advantage of level triggered interrupt, and 
> just want to deassert after it receive it for e.g. 10 times. Then we would got 
> the trouble. But it's so tricky and we don't know any device by now take this 
> way yet. Of course they can, so we also suggest to use a whitelist/blacklist 
> for this approach. But this should work in most condition.
>
> Yeah, it's aggressive, but we think it's reasonable, and tested OK (in my 
> limited environment). Also I heard that Hyper-V or Vmware did this.
>
> Any more concerns? Hope we didn't neglect something.
>   

Please add a module parameter to disable msi->pciirq conversion in that 
case.  So if someone runs into trouble, we can try out the alternative.

-- 
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