s390x/pci: fix failures of dma map/unmap

In commit d78c19b5, vfio code stores
the IOMMU's offset_within_address_space and adjusts the IOVA before
calling vfio_dma_map/vfio_dma_unmap. But s390_translate_iommu already
considers the base address of an IOMMU memory region.

Thus we use pal as the size and 0x0 as the base address to initialize
IOMMU memory subregion.
Signed-off-by: NYi Min Zhao <zyimin@linux.vnet.ibm.com>
Reviewed-by: NPierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

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;
 }