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Boris Ostrovsky authored
commit ff1e22e7 upstream. Moving an unmasked irq may result in irq handler being invoked on both source and target CPUs. With 2-level this can happen as follows: On source CPU: evtchn_2l_handle_events() -> generic_handle_irq() -> handle_edge_irq() -> eoi_pirq(): irq_move_irq(data); /***** WE ARE HERE *****/ if (VALID_EVTCHN(evtchn)) clear_evtchn(evtchn); If at this moment target processor is handling an unrelated event in evtchn_2l_handle_events()'s loop it may pick up our event since target's cpu_evtchn_mask claims that this event belongs to it *and* the event is unmasked and still pending. At the same time, source CPU will continue executing its own handle_edge_irq(). With FIFO interrupt the scenario is similar: irq_move_irq() may result in a EVTCHNOP_unmask hypercall which, in turn, may make the event pending on the target CPU. We can avoid this situation by moving and clearing the event while keeping event masked. Signed-off-by:
Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by:
David Vrabel <david.vrabel@citrix.com> Signed-off-by:
Ben Hutchings <ben@decadent.org.uk>
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