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authorBoris Ostrovsky <boris.ostrovsky@oracle.com>2016-03-18 10:11:07 -0400
committerDavid Vrabel <david.vrabel@citrix.com>2016-04-04 11:18:00 +0100
commitff1e22e7a638a0782f54f81a6c9cb139aca2da35 (patch)
tree6dad8a5e1792259b3ec1258d04fb35fd72987347
parent85d1a29de8e4e5bce20ca02103acf1082a6e530a (diff)
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>
-rw-r--r--drivers/xen/events/events_base.c28
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);
}