Index: sys/xen/xen_intr.c
===================================================================
--- sys/xen/xen_intr.c
+++ sys/xen/xen_intr.c
@@ -281,7 +281,7 @@
 	isrc = xen_intr_find_unused_isrc(type);
 	if (isrc != NULL) {
 		mtx_unlock(&xen_intr_x86_lock);
-		return (isrc);
+		goto out;
 	}
 
 	if (xen_intr_auto_vector_count >= NR_EVENT_CHANNELS) {
@@ -311,6 +311,18 @@
 		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);
 }
 
@@ -390,6 +402,9 @@
 {
 	struct xenisrc *isrc;
 	int error;
+#ifdef SMP
+	u_int cpu;
+#endif
 
 	*isrcp = NULL;
 	if (port_handlep == NULL) {
@@ -402,6 +417,9 @@
 		return (ENOSPC);
 	isrc->xi_port = local_port;
 	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);
 	if (__predict_false(xen_intr_port_to_isrc[isrc->xi_port] != NULL)) {
@@ -421,7 +439,7 @@
 		 * 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