diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index a77c10ce9e..8f03b82469 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -498,11 +498,9 @@ static const MemoryRegionOps s390_msi_ctrl_ops = {
 
 void s390_pci_iommu_enable(S390PCIBusDevice *pbdev)
 {
-    uint64_t size = pbdev->pal - pbdev->pba + 1;
-
     memory_region_init_iommu(&pbdev->iommu_mr, OBJECT(&pbdev->mr),
-                             &s390_iommu_ops, "iommu-s390", size);
-    memory_region_add_subregion(&pbdev->mr, pbdev->pba, &pbdev->iommu_mr);
+                             &s390_iommu_ops, "iommu-s390", pbdev->pal + 1);
+    memory_region_add_subregion(&pbdev->mr, 0, &pbdev->iommu_mr);
     pbdev->iommu_enabled = true;
 }