Messages in this thread | | | Subject | Re: [PATCH v2 6/6] kvm: Level IRQ de-assert for KVM_IRQFD | From | Alex Williamson <> | Date | Fri, 29 Jun 2012 09:39:51 -0600 |
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On Thu, 2012-06-28 at 15:59 +0300, Avi Kivity wrote: > On 06/27/2012 08:10 AM, Alex Williamson wrote: > > This is an alternate level irqfd de-assert mode that's potentially > > useful for emulated drivers. It's included here to show how easy it > > is to implement with the new level irqfd and eoifd support. It's > > possible this mode might also prove interesting for device-assignment > > where we inject via level irqfd, receive an EOI (w/o de-assert), and > > use the level de-assert irqfd here. > > This use case is racy. The guest driver will have shut down the > interrupt before EOI, but with what you describe, it will fire again > until the eoifd/deassertfd sequence completes.
Hmm, that's a good point. We'll continue asserting the interrupt in the indeterminate gap between eoifd and de-assert-irqfd which could fire enough times for the guest to disable it. Oh well. Thanks,
Alex
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