1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index a58ac435a9a4..5e8be462aed5 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -348,7 +348,7 @@ static void init_evtchn_cpu_bindings(void)
 
         for_each_possible_cpu(i)
                 memset(per_cpu(cpu_evtchn_mask, i),
-                       (i == 0) ? ~0 : 0, sizeof(*per_cpu(cpu_evtchn_mask, i)));
+                       (i == 0) ? ~0 : 0, NR_EVENT_CHANNELS/8);
 }
 
 static inline void clear_evtchn(int port)
@@ -1493,8 +1493,10 @@ void rebind_evtchn_irq(int evtchn, int irq)
 /* Rebind an evtchn so that it gets delivered to a specific cpu */
 static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
 {
+        struct shared_info *s = HYPERVISOR_shared_info;
         struct evtchn_bind_vcpu bind_vcpu;
         int evtchn = evtchn_from_irq(irq);
+        int masked;
 
         if (!VALID_EVTCHN(evtchn))
                 return -1;
@@ -1511,6 +1513,12 @@ static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
         bind_vcpu.vcpu = tcpu;
 
         /*
+         * Mask the event while changing the VCPU binding to prevent
+         * it being delivered on an unexpected VCPU.
+         */
+        masked = sync_test_and_set_bit(evtchn, BM(s->evtchn_mask));
+
+        /*
          * If this fails, it usually just indicates that we're dealing with a
          * virq or IPI channel, which don't actually need to be rebound. Ignore
          * it, but don't do the xenlinux-level rebind in that case.
@@ -1518,6 +1526,9 @@ static int rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
         if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
                 bind_evtchn_to_cpu(evtchn, tcpu);
 
+        if (!masked)
+                unmask_evtchn(evtchn);
+
         return 0;
 }