diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index d5712ae754..98c726cfcd 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -308,7 +308,7 @@ static IOMMUTLBEntry s390_translate_iommu(MemoryRegion *iommu, hwaddr addr,
 {
     uint64_t pte;
     uint32_t flags;
-    S390PCIBusDevice *pbdev = container_of(iommu, S390PCIBusDevice, mr);
+    S390PCIBusDevice *pbdev = container_of(iommu, S390PCIBusDevice, iommu_mr);
     S390pciState *s;
     IOMMUTLBEntry ret = {
         .target_as = &address_space_memory,
@@ -454,14 +454,32 @@ static const MemoryRegionOps s390_msi_ctrl_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
+void s390_pcihost_iommu_configure(S390PCIBusDevice *pbdev, bool enable)
+{
+    pbdev->configured = false;
+
+    if (enable) {
+        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);
+    } else {
+        memory_region_del_subregion(&pbdev->mr, &pbdev->iommu_mr);
+    }
+
+    pbdev->configured = true;
+}
+
 static void s390_pcihost_init_as(S390pciState *s)
 {
     int i;
+    S390PCIBusDevice *pbdev;
 
     for (i = 0; i < PCI_SLOT_MAX; i++) {
-        memory_region_init_iommu(&s->pbdev[i].mr, OBJECT(s),
-                                 &s390_iommu_ops, "iommu-s390", UINT64_MAX);
-        address_space_init(&s->pbdev[i].as, &s->pbdev[i].mr, "iommu-pci");
+        pbdev = &s->pbdev[i];
+        memory_region_init(&pbdev->mr, OBJECT(s),
+                           "iommu-root-s390", UINT64_MAX);
+        address_space_init(&pbdev->as, &pbdev->mr, "iommu-pci");
     }
 
     memory_region_init_io(&s->msix_notify_mr, OBJECT(s),
diff --git a/hw/s390x/s390-pci-bus.h b/hw/s390x/s390-pci-bus.h
index 464a92eedf..80345dacb1 100644
--- a/hw/s390x/s390-pci-bus.h
+++ b/hw/s390x/s390-pci-bus.h
@@ -231,6 +231,7 @@ typedef struct S390PCIBusDevice {
     AdapterRoutes routes;
     AddressSpace as;
     MemoryRegion mr;
+    MemoryRegion iommu_mr;
 } S390PCIBusDevice;
 
 typedef struct S390pciState {
@@ -244,6 +245,7 @@ typedef struct S390pciState {
 int chsc_sei_nt2_get_event(void *res);
 int chsc_sei_nt2_have_event(void);
 void s390_pci_sclp_configure(int configure, SCCB *sccb);
+void s390_pcihost_iommu_configure(S390PCIBusDevice *pbdev, bool enable);
 S390PCIBusDevice *s390_pci_find_dev_by_idx(uint32_t idx);
 S390PCIBusDevice *s390_pci_find_dev_by_fh(uint32_t fh);
 S390PCIBusDevice *s390_pci_find_dev_by_fid(uint32_t fid);
diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
index f9151a9afb..8c1dc82b1f 100644
--- a/hw/s390x/s390-pci-inst.c
+++ b/hw/s390x/s390-pci-inst.c
@@ -528,7 +528,7 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2)
         goto out;
     }
 
-    mr = pci_device_iommu_address_space(pbdev->pdev)->root;
+    mr = &pbdev->iommu_mr;
     while (start < end) {
         entry = mr->iommu_ops->translate(mr, start, 0);
 
@@ -689,6 +689,9 @@ static int reg_ioat(CPUS390XState *env, S390PCIBusDevice *pbdev, ZpciFib fib)
     pbdev->pba = pba;
     pbdev->pal = pal;
     pbdev->g_iota = g_iota;
+
+    s390_pcihost_iommu_configure(pbdev, true);
+
     return 0;
 }
 
@@ -697,6 +700,8 @@ static void dereg_ioat(S390PCIBusDevice *pbdev)
     pbdev->pba = 0;
     pbdev->pal = 0;
     pbdev->g_iota = 0;
+
+    s390_pcihost_iommu_configure(pbdev, false);
 }
 
 int mpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar)