RE: [Xen-devel] [PATCH][RFC] pv-ops: fix shared irq device passthrough

["Kay, Allen M" <allen.m.kay@xxxxxxxxx>]

> With this patch you can share the PCI devices on the same IRQ, correct? Will
> this mean that you can assign to a guest a USB controller, while
> Dom0 has controller of the PCI NIC (and assuming that both of those
> share the same interrupt line)? If so, won't the Dom0 start throwing
> a fit b/c there are unhandled IRQs and eventually disable the IRQ line?

No, interrupts are injected to both domains sharing the same IRQ.
See arch/x86/irq.c/__do_IRQ_guest() for details.

> Or even the guest decide that there are too many IRQs and decided to
> disable the IRQ line?

Note that in __do_IRQ_guest(), interrupt handling control flow for PCI 
passthrough case
Is the same for PV event channel case.  Guest doesn't disable the IRQ line 
unless
there is a malfunction.

Allen

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