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author | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2016-03-18 15:11:07 +0100 |
---|---|---|
committer | David Vrabel <david.vrabel@citrix.com> | 2016-04-04 12:18:00 +0200 |
commit | ff1e22e7a638a0782f54f81a6c9cb139aca2da35 (patch) | |
tree | 6dad8a5e1792259b3ec1258d04fb35fd72987347 /drivers/xen/events | |
parent | Xen on ARM and ARM64: update MAINTAINERS info (diff) | |
download | linux-ff1e22e7a638a0782f54f81a6c9cb139aca2da35.tar.xz linux-ff1e22e7a638a0782f54f81a6c9cb139aca2da35.zip |
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>
Diffstat (limited to 'drivers/xen/events')
-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 488017a0806a..cb7138c97c69 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); } |