return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
 }
 
+static bool attach_deferred(struct device *dev)
+{
+       return dev->archdata.iommu == DEFER_DEVICE_DOMAIN_INFO;
+}
+
 /**
  * is_downstream_to_pci_bridge - test if a device belongs to the PCI
  *                              sub-hierarchy of a candidate PCI-PCI bridge
 {
        struct device_domain_info *info;
 
-       if (unlikely(dev->archdata.iommu == DEFER_DEVICE_DOMAIN_INFO ||
-                    dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO))
+       if (unlikely(attach_deferred(dev) || iommu_dummy(dev)))
                return NULL;
 
        if (dev_is_pci(dev))
 
 static struct dmar_domain *deferred_attach_domain(struct device *dev)
 {
-       if (unlikely(dev->archdata.iommu == DEFER_DEVICE_DOMAIN_INFO)) {
+       if (unlikely(attach_deferred(dev))) {
                struct iommu_domain *domain;
 
                dev->archdata.iommu = NULL;
 static bool intel_iommu_is_attach_deferred(struct iommu_domain *domain,
                                           struct device *dev)
 {
-       return dev->archdata.iommu == DEFER_DEVICE_DOMAIN_INFO;
+       return attach_deferred(dev);
 }
 
 static int