Index: sys/dev/xen/bus/xen_intr.c
===================================================================
--- sys/dev/xen/bus/xen_intr.c
+++ sys/dev/xen/bus/xen_intr.c
@@ -319,7 +319,6 @@
 
 		xen_intr_port_to_isrc[isrc->xi_port] = NULL;
 	}
-	isrc->xi_cpu = 0;
 	isrc->xi_type = EVTCHN_TYPE_UNBOUND;
 	isrc->xi_port = INVALID_EVTCHN;
 	mtx_unlock(&xen_intr_isrc_lock);
@@ -348,9 +347,10 @@
  *
  * \returns  0 on success, otherwise an errno.
  */
-#define BIND_PARAMS(type, ...) \
+#define BIND_PARAMS(type, cpu, ...) \
 {						\
 	.xi_type = (type),			\
+	.xi_cpu = (cpu),			\
 	.xi_cookie = NULL,			\
 	__VA_ARGS__				\
 }
@@ -361,6 +361,9 @@
 {
 	struct xenisrc *isrc;
 	int error;
+#ifdef SMP
+	u_int cpu;
+#endif
 
 	*isrcp = NULL;
 	if (port_handlep == NULL) {
@@ -372,6 +375,10 @@
 	if (isrc == NULL)
 		return (ENOSPC);
 	refcount_init(&isrc->xi_refcount, 1);
+#ifdef SMP
+	cpu = isrc->xi_cpu;
+#endif
+	isrc->xi_cpu = 0; /* initialize to the likely correct value */
 	mtx_lock(&xen_intr_isrc_lock);
 	xen_intr_port_to_isrc[isrc->xi_port] = isrc;
 	mtx_unlock(&xen_intr_isrc_lock);
@@ -382,13 +389,29 @@
 	/* ->xi_cookie is cleared in BIND_PARAMS() */
 
 #ifdef SMP
-	if (isrc->xi_type == EVTCHN_TYPE_PORT) {
+	if (cpu > mp_maxid) {
 		/*
 		 * By default all interrupts are assigned to vCPU#0
 		 * unless specified otherwise, so shuffle them to balance
 		 * the interrupt load.
 		 */
-		xen_intr_assign_cpu(isrc, intr_next_cpu(0));
+		cpu = intr_next_cpu(0);
+	}
+
+	error = xen_arch_intr_event_bind(isrc, cpu);
+	if (error != 0) { /* *very* unlikely */
+		xen_intr_release_isrc(isrc);
+		return (error);
+	}
+
+	if (isrc->xi_cpu != cpu) {
+		/*
+		 * Too early in the boot process for the generic interrupt
+		 * code to perform the binding.  Update our event channel
+		 * masks manually so events can't fire on the wrong cpu
+		 * during AP startup.
+		 */
+		xen_intr_assign_cpu(isrc, cpu);
 	}
 #endif
 
@@ -848,7 +871,7 @@
     enum intr_type flags, xen_intr_handle_t *port_handlep)
 {
 	struct xenisrc *isrc;
-	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_PORT,
+	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_PORT, ~0U,
 		.xi_port = local_port,
 		/*
 		 * The Event Channel API didn't open this port, so it is not
@@ -867,7 +890,7 @@
     enum intr_type flags, xen_intr_handle_t *port_handlep)
 {
 	struct xenisrc *isrc;
-	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_PORT);
+	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_PORT, ~0U);
 	struct evtchn_alloc_unbound alloc_unbound;
 	int error;
 
@@ -903,7 +926,7 @@
     void *arg, enum intr_type flags, xen_intr_handle_t *port_handlep)
 {
 	struct xenisrc *isrc;
-	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_PORT);
+	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_PORT, ~0U);
 	struct evtchn_bind_interdomain bind_interdomain;
 	int error;
 
@@ -944,7 +967,7 @@
 {
 	u_int vcpu_id = XEN_CPUID_TO_VCPUID(cpu);
 	struct xenisrc *isrc;
-	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_VIRQ,
+	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_VIRQ, cpu,
 		.xi_virq = virq,
 	);
 	struct evtchn_bind_virq bind_virq = { .virq = virq, .vcpu = vcpu_id };
@@ -964,11 +987,6 @@
 	error = xen_intr_bind_isrc(&isrc, &params, device_get_nameunit(dev),
 	    filter, handler, arg, flags, port_handlep);
 
-#ifdef SMP
-	if (error == 0)
-		error = xen_arch_intr_event_bind(isrc, cpu);
-#endif
-
 	if (error != 0) {
 		evtchn_close_t close = { .port = params.xi_port };
 
@@ -978,18 +996,6 @@
 		return (error);
 	}
 
-#ifdef SMP
-	if (isrc->xi_cpu != cpu) {
-		/*
-		 * Too early in the boot process for the generic interrupt
-		 * code to perform the binding.  Update our event channel
-		 * masks manually so events can't fire on the wrong cpu
-		 * during AP startup.
-		 */
-		xen_intr_assign_cpu(isrc, cpu);
-	}
-#endif
-
 	/*
 	 * The Event Channel API opened this port, so it is
 	 * responsible for closing it automatically on unbind.
@@ -1006,7 +1012,7 @@
 #ifdef SMP
 	u_int vcpu_id = XEN_CPUID_TO_VCPUID(cpu);
 	struct xenisrc *isrc;
-	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_IPI);
+	struct xenisrc params = BIND_PARAMS(EVTCHN_TYPE_IPI, cpu);
 	struct evtchn_bind_ipi bind_ipi = { .vcpu = vcpu_id };
 	/* Same size as the one used by intr_handler->ih_name. */
 	char name[MAXCOMLEN + 1];
@@ -1036,16 +1042,6 @@
 		return (error);
 	}
 
-	if (isrc->xi_cpu != cpu) {
-		/*
-		 * Too early in the boot process for the generic interrupt
-		 * code to perform the binding.  Update our event channel
-		 * masks manually so events can't fire on the wrong cpu
-		 * during AP startup.
-		 */
-		xen_intr_assign_cpu(isrc, cpu);
-	}
-
 	/*
 	 * The Event Channel API opened this port, so it is
 	 * responsible for closing it automatically on unbind.