xen/events: Mask a moving irq
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> Cc: stable@vger.kernel.org Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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@ -484,9 +484,19 @@ static void eoi_pirq(struct irq_data *data)
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struct physdev_eoi eoi = { .irq = pirq_from_irq(data->irq) };
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int rc = 0;
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irq_move_irq(data);
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if (!VALID_EVTCHN(evtchn))
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return;
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if (VALID_EVTCHN(evtchn))
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if (unlikely(irqd_is_setaffinity_pending(data))) {
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int masked = test_and_set_mask(evtchn);
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clear_evtchn(evtchn);
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irq_move_masked_irq(data);
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if (!masked)
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unmask_evtchn(evtchn);
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} else
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clear_evtchn(evtchn);
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if (pirq_needs_eoi(data->irq)) {
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@ -1357,9 +1367,19 @@ static void ack_dynirq(struct irq_data *data)
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{
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int evtchn = evtchn_from_irq(data->irq);
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irq_move_irq(data);
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if (!VALID_EVTCHN(evtchn))
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return;
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if (VALID_EVTCHN(evtchn))
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if (unlikely(irqd_is_setaffinity_pending(data))) {
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int masked = test_and_set_mask(evtchn);
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clear_evtchn(evtchn);
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irq_move_masked_irq(data);
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if (!masked)
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unmask_evtchn(evtchn);
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} else
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clear_evtchn(evtchn);
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}
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