diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 71f307a572e9..d228da641367 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2503,7 +2503,7 @@ static int __init handle_device(struct domain *d, struct dt_device_node *dev,
             return res;
         }
 
-        if ( dt_device_is_protected(dev) )
+        if ( device_is_protected(dt_to_dev(dev)) )
         {
             dt_dprintk("%s setup iommu\n", dt_node_full_name(dev));
             res = iommu_assign_dt_device(d, dev);
@@ -3003,7 +3003,7 @@ static int __init handle_passthrough_prop(struct kernel_info *kinfo,
         return res;
 
     /* If xen_force, we allow assignment of devices without IOMMU protection. */
-    if ( xen_force && !dt_device_is_protected(node) )
+    if ( xen_force && !device_is_protected(dt_to_dev(node)) )
         return 0;
 
     return iommu_assign_dt_device(kinfo->d, node);
diff --git a/xen/arch/arm/include/asm/device.h b/xen/arch/arm/include/asm/device.h
index b5d451e08776..086dde13eb6b 100644
--- a/xen/arch/arm/include/asm/device.h
+++ b/xen/arch/arm/include/asm/device.h
@@ -1,6 +1,8 @@
 #ifndef __ASM_ARM_DEVICE_H
 #define __ASM_ARM_DEVICE_H
 
+#include <xen/types.h>
+
 enum device_type
 {
     DEV_DT,
@@ -20,6 +22,7 @@ struct device
 #endif
     struct dev_archdata archdata;
     struct iommu_fwspec *iommu_fwspec; /* per-device IOMMU instance data */
+    bool is_protected; /* Shows that device is protected by IOMMU */
 };
 
 typedef struct device device_t;
@@ -94,6 +97,16 @@ int device_init(struct dt_device_node *dev, enum device_class class,
  */
 enum device_class device_get_class(const struct dt_device_node *dev);
 
+static inline void device_set_protected(struct device *device)
+{
+    device->is_protected = true;
+}
+
+static inline bool device_is_protected(const struct device *device)
+{
+    return device->is_protected;
+}
+
 #define DT_DEVICE_START(_name, _namestr, _class)                    \
 static const struct device_desc __dev_desc_##_name __used           \
 __section(".dev.info") = {                                          \
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 6c9712ab7bda..1d5d7cb5f01b 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -1874,7 +1874,7 @@ static unsigned long __init unflatten_dt_node(const void *fdt,
         /* By default dom0 owns the device */
         np->used_by = 0;
         /* By default the device is not protected */
-        np->is_protected = false;
+        np->dev.is_protected = false;
         INIT_LIST_HEAD(&np->domain_list);
 
         if ( new_format )
diff --git a/xen/drivers/passthrough/arm/ipmmu-vmsa.c b/xen/drivers/passthrough/arm/ipmmu-vmsa.c
index 091f09b21752..039212a3a990 100644
--- a/xen/drivers/passthrough/arm/ipmmu-vmsa.c
+++ b/xen/drivers/passthrough/arm/ipmmu-vmsa.c
@@ -1288,14 +1288,8 @@ static int ipmmu_add_device(u8 devfn, struct device *dev)
     if ( !to_ipmmu(dev) )
         return -ENODEV;
 
-    if ( dt_device_is_protected(dev_to_dt(dev)) )
-    {
-        dev_err(dev, "Already added to IPMMU\n");
-        return -EEXIST;
-    }
-
     /* Let Xen know that the master device is protected by an IOMMU. */
-    dt_device_set_protected(dev_to_dt(dev));
+    device_set_protected(dev);
 
     dev_info(dev, "Added master device (IPMMU %s micro-TLBs %u)\n",
              dev_name(fwspec->iommu_dev), fwspec->num_ids);
diff --git a/xen/drivers/passthrough/arm/smmu-v3.c b/xen/drivers/passthrough/arm/smmu-v3.c
index 4ca55d400a7b..f5910e79922f 100644
--- a/xen/drivers/passthrough/arm/smmu-v3.c
+++ b/xen/drivers/passthrough/arm/smmu-v3.c
@@ -1521,13 +1521,8 @@ static int arm_smmu_add_device(u8 devfn, struct device *dev)
 	 */
 	arm_smmu_enable_pasid(master);
 
-	if (dt_device_is_protected(dev_to_dt(dev))) {
-		dev_err(dev, "Already added to SMMUv3\n");
-		return -EEXIST;
-	}
-
 	/* Let Xen know that the master device is protected by an IOMMU. */
-	dt_device_set_protected(dev_to_dt(dev));
+	device_set_protected(dev);
 
 	dev_info(dev, "Added master device (SMMUv3 %s StreamIds %u)\n",
 			dev_name(fwspec->iommu_dev), fwspec->num_ids);
diff --git a/xen/drivers/passthrough/arm/smmu.c b/xen/drivers/passthrough/arm/smmu.c
index 0a514821b336..5b6024d579a8 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -838,7 +838,7 @@ static int arm_smmu_dt_add_device_legacy(struct arm_smmu_device *smmu,
 	master->of_node = dev_node;
 
 	/* Xen: Let Xen know that the device is protected by an SMMU */
-	dt_device_set_protected(dev_node);
+	device_set_protected(dev);
 
 	for (i = 0; i < fwspec->num_ids; ++i) {
 		if (!(smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) &&
diff --git a/xen/drivers/passthrough/device_tree.c b/xen/drivers/passthrough/device_tree.c
index 1c32d7b50cce..b5bd13393b56 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -34,7 +34,7 @@ int iommu_assign_dt_device(struct domain *d, struct dt_device_node *dev)
     if ( !is_iommu_enabled(d) )
         return -EINVAL;
 
-    if ( !dt_device_is_protected(dev) )
+    if ( !device_is_protected(dt_to_dev(dev)) )
         return -EINVAL;
 
     spin_lock(&dtdevs_lock);
@@ -65,7 +65,7 @@ int iommu_deassign_dt_device(struct domain *d, struct dt_device_node *dev)
     if ( !is_iommu_enabled(d) )
         return -EINVAL;
 
-    if ( !dt_device_is_protected(dev) )
+    if ( !device_is_protected(dt_to_dev(dev)) )
         return -EINVAL;
 
     spin_lock(&dtdevs_lock);
@@ -87,7 +87,7 @@ static bool_t iommu_dt_device_is_assigned(const struct dt_device_node *dev)
 {
     bool_t assigned = 0;
 
-    if ( !dt_device_is_protected(dev) )
+    if ( !device_is_protected(dt_to_dev(dev)) )
         return 0;
 
     spin_lock(&dtdevs_lock);
@@ -141,12 +141,15 @@ int iommu_add_dt_device(struct dt_device_node *np)
         return -EINVAL;
 
     /*
-     * The device may already have been registered. As there is no harm in
-     * it just return success early.
+     * This is needed in case a device has both the iommus property and
+     * also appears in the mmu-masters list.
      */
-    if ( dev_iommu_fwspec_get(dev) )
+    if ( device_is_protected(dev) )
         return 0;
 
+    if ( dev_iommu_fwspec_get(dev) )
+        return -EEXIST;
+
     /*
      * According to the Documentation/devicetree/bindings/iommu/iommu.txt
      * from Linux.
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index 19a74909cece..c1e4751a581f 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -90,9 +90,6 @@ struct dt_device_node {
     struct dt_device_node *next; /* TODO: Remove it. Only use to know the last children */
     struct dt_device_node *allnext;
 
-    /* IOMMU specific fields */
-    bool is_protected;
-
     /* HACK: Remove this if there is a need of space */
     bool_t static_evtchn_created;
 
@@ -302,16 +299,6 @@ static inline domid_t dt_device_used_by(const struct dt_device_node *device)
     return device->used_by;
 }
 
-static inline void dt_device_set_protected(struct dt_device_node *device)
-{
-    device->is_protected = true;
-}
-
-static inline bool dt_device_is_protected(const struct dt_device_node *device)
-{
-    return device->is_protected;
-}
-
 static inline bool_t dt_property_name_is_equal(const struct dt_property *pp,
                                                const char *name)
 {
