diff --git a/xen/arch/arm/domctl.c b/xen/arch/arm/domctl.c
index 6245af6d0b..1baf25c3d9 100644
--- a/xen/arch/arm/domctl.c
+++ b/xen/arch/arm/domctl.c
@@ -176,16 +176,7 @@ long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
         return rc;
     }
     default:
-    {
-        int rc;
-
-        rc = subarch_do_domctl(domctl, d, u_domctl);
-
-        if ( rc == -ENOSYS )
-            rc = iommu_do_domctl(domctl, d, u_domctl);
-
-        return rc;
-    }
+        return subarch_do_domctl(domctl, d, u_domctl);
     }
 }
 
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index c20ab43527..1c62046c01 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1370,7 +1370,7 @@ long arch_do_domctl(
         break;
 
     default:
-        ret = iommu_do_domctl(domctl, d, u_domctl);
+        ret = -ENOSYS;
         break;
     }
 
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 5879117580..0a866e3132 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -871,6 +871,13 @@ long cf_check do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
             copyback = 1;
         break;
 
+    case XEN_DOMCTL_assign_device:
+    case XEN_DOMCTL_test_assign_device:
+    case XEN_DOMCTL_deassign_device:
+    case XEN_DOMCTL_get_device_group:
+        ret = iommu_do_domctl(op, d, u_domctl);
+        break;
+
     default:
         ret = arch_do_domctl(op, d, u_domctl);
         break;
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index f7e8d5f287..db72d9e644 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -342,8 +342,17 @@ struct domain_iommu {
 /* Does the IOMMU pagetable need to be kept synchronized with the P2M */
 #ifdef CONFIG_HAS_PASSTHROUGH
 #define need_iommu_pt_sync(d)     (dom_iommu(d)->need_sync)
+
+int iommu_do_domctl(struct xen_domctl *domctl, struct domain *d,
+                    XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl);
 #else
 #define need_iommu_pt_sync(d)     ({ (void)(d); false; })
+
+static inline int iommu_do_domctl(struct xen_domctl *domctl, struct domain *d,
+                                  XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
+{
+    return -ENOSYS;
+}
 #endif
 
 int __must_check iommu_suspend(void);
@@ -357,9 +366,6 @@ int iommu_do_pci_domctl(struct xen_domctl *, struct domain *d,
                         XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
 #endif
 
-int iommu_do_domctl(struct xen_domctl *, struct domain *d,
-                    XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
-
 void iommu_dev_iotlb_flush_timeout(struct domain *d, struct pci_dev *pdev);
 
 /*