Index: sys/xen/xen_intr.c
===================================================================
--- sys/xen/xen_intr.c
+++ sys/xen/xen_intr.c
@@ -281,7 +281,7 @@
 
 	if (isrc != NULL) {
 		mtx_unlock(&xen_intr_x86_lock);
-		return (isrc);
+		goto out;
 	}
 
 	if (xen_intr_auto_vector_count >= NR_EVENT_CHANNELS) {
@@ -309,6 +309,18 @@
 		return (NULL);
 	}
 
+out:
+#ifdef SMP
+	if (type == EVTCHN_TYPE_PORT) {
+		/*
+		 * By default all interrupts are assigned to vCPU#0
+		 * unless specified otherwise, so shuffle them to balance
+		 * the interrupt load.
+		 */
+		isrc->xi_cpu = intr_next_cpu(0);
+	}
+#endif
+
 	return (isrc);
 }
 
@@ -410,12 +422,15 @@
 
 #ifdef SMP
 	if (type == EVTCHN_TYPE_PORT) {
+		u_int cpu = isrc->xi_cpu;
+
+		isrc->xi_cpu = 0;
 		/*
 		 * 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));
+		xen_intr_assign_cpu(isrc, cpu);
 	}
 #endif