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);
 }
 
@@ -386,6 +398,7 @@
     xen_intr_handle_t *port_handlep)
 {
 	struct xenisrc *isrc;
+	u_int cpu;
 	int error;
 
 	*isrcp = NULL;
@@ -398,11 +411,13 @@
 	if (isrc == NULL)
 		return (ENOSPC);
 	isrc->xi_port = local_port;
+	cpu = isrc->xi_cpu;
 	mtx_lock(&xen_intr_isrc_lock);
 	if (xen_intr_port_to_isrc[isrc->xi_port] != NULL) {
 		xen_intr_port_to_isrc[isrc->xi_port]->xi_port = ~0U;
 		isrc->xi_cpu = xen_intr_port_to_isrc[isrc->xi_port]->xi_cpu;
-	}
+	} else
+		isrc->xi_cpu = 0;
 	xen_intr_port_to_isrc[isrc->xi_port] = isrc;
 	refcount_init(&isrc->xi_refcount, 1);
 	mtx_unlock(&xen_intr_isrc_lock);
@@ -417,7 +432,7 @@
 		 * 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