diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 78552886612e..3b4cacb7bc47 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2856,6 +2856,15 @@ static void vfio_ap_mdev_hot_plug_cfg(struct ap_matrix_mdev *matrix_mdev)
 	DECLARE_BITMAP(apm_filtered, AP_DEVICES);
 	bool filter_domains, filter_adapters, filter_cdoms, do_hotplug = false;
 
+	/*
+	 * Zero out the apm_filtered bitmap in case there are no adapters or
+	 * domains to be added, but only control domains. In that case,
+	 * vfio_ap_mdev_filter_matrix() - which initializes apm_filtered - will
+	 * not get called and the reset_queues_for_apids will crash because it
+	 * will access an uninitialized bitmap.
+	 */
+	bitmap_zero(apm_filtered, AP_DEVICES);
+
 	filter_adapters = bitmap_intersects(matrix_mdev->matrix.apm,
 					    matrix_mdev->apm_add, AP_DEVICES);
 	filter_domains = bitmap_intersects(matrix_mdev->matrix.aqm,