Index: sys/arm64/arm64/gicv3_its.c
===================================================================
--- sys/arm64/arm64/gicv3_its.c
+++ sys/arm64/arm64/gicv3_its.c
@@ -1411,10 +1411,13 @@
 	struct gicv3_its_irqsrc *girq;
 
 	sc = device_get_softc(dev);
-	girq = (struct gicv3_its_irqsrc *)isrc;
 
 	*addr = vtophys(rman_get_virtual(sc->sc_its_res)) + GITS_TRANSLATER;
-	*data = girq->gi_id;
+
+	if (isrc != NULL && data != NULL) {
+		girq = (struct gicv3_its_irqsrc *)isrc;
+		*data = girq->gi_id;
+	}
 
 	return (0);
 }
Index: sys/kern/subr_intr.c
===================================================================
--- sys/kern/subr_intr.c
+++ sys/kern/subr_intr.c
@@ -1441,9 +1441,12 @@
 	    ("%s: Found a non-MSI controller: %s", __func__,
 	     device_get_name(pic->pic_dev)));
 
-	isrc = intr_map_get_isrc(irq);
-	if (isrc == NULL)
-		return (EINVAL);
+	if (irq >= 0) {
+		isrc = intr_map_get_isrc(irq);
+		if (isrc == NULL)
+			return (EINVAL);
+	} else
+		isrc = NULL;
 
 	err = MSI_MAP_MSI(pic->pic_dev, child, isrc, addr, data);
 	return (err);