diff options
| author | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2016-03-18 10:11:07 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-20 15:41:56 +0900 |
| commit | 0cc60c58ba3fcbc8467a3d56b98c664b0fc7d9bb (patch) | |
| tree | 4f54b26a6603b2375354335684d51d331f9a5259 /drivers/xen | |
| parent | 40a8f74321fb892dec5757ca44ec3850bde26a24 (diff) | |
xen/events: Mask a moving irq
commit ff1e22e7a638a0782f54f81a6c9cb139aca2da35 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/events/events_base.c | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 524c22146429..44367783f07a 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -484,9 +484,19 @@ static void eoi_pirq(struct irq_data *data) struct physdev_eoi eoi = { .irq = pirq_from_irq(data->irq) }; int rc = 0; - irq_move_irq(data); + if (!VALID_EVTCHN(evtchn)) + return; - if (VALID_EVTCHN(evtchn)) + if (unlikely(irqd_is_setaffinity_pending(data))) { + int masked = test_and_set_mask(evtchn); + + clear_evtchn(evtchn); + + irq_move_masked_irq(data); + + if (!masked) + unmask_evtchn(evtchn); + } else clear_evtchn(evtchn); if (pirq_needs_eoi(data->irq)) { @@ -1357,9 +1367,19 @@ static void ack_dynirq(struct irq_data *data) { int evtchn = evtchn_from_irq(data->irq); - irq_move_irq(data); + if (!VALID_EVTCHN(evtchn)) + return; - if (VALID_EVTCHN(evtchn)) + if (unlikely(irqd_is_setaffinity_pending(data))) { + int masked = test_and_set_mask(evtchn); + + clear_evtchn(evtchn); + + irq_move_masked_irq(data); + + if (!masked) + unmask_evtchn(evtchn); + } else clear_evtchn(evtchn); } |