On Sun, 2010-07-11 at 23:12 +0300, Michael S. Tsirkin wrote: > On Sun, Jul 11, 2010 at 02:03:34PM -0600, Alex Williamson wrote: > > > What about threaded interrupts? > > Just to make the point, imagine a nested virt situation > which uses current kvm device assignment in guest. > Look at the interrupt handler we have there. Is the problem you're worried about this: guest masks qemu ioapic rte device interrupt host vfio DisINTx+ qemu vfio calls qemu_set_irq ... In that case, the qemu ioapic irr bit is only toggled by qemu_set_irq for level triggered interrupts, so the interrupt will be asserted in the guest when it gets unmasked and we'll get the eoi. I can't figure out where your other scenario can leave the DisINTx+: device asserts interrupt a) DisINTx+ via host vfio guest disables interrupt b) DisINTx+ via guest, already set eoi c) DisINTx- via qemu vfio driver clears interrupt guest enables interrupt d) DisINTx- via guest device asserts interrupt So between c) & d) we're potentially getting more interrupts than we want, but I can't see anywhere that we drop DisINTx. If you have a scenario, let me know. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
