diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index b1c29529514f..5cb84864b89b 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -10,6 +10,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <xen/bitops.h>
 #include <xen/types.h>
 #include <xen/init.h>
 #include <xen/guest_access.h>
@@ -2243,6 +2244,96 @@ int dt_get_pci_domain_nr(struct dt_device_node *node)
     return (u16)domain;
 }
 
+int dt_map_id(const struct dt_device_node *np, uint32_t id,
+              const char *map_name, const char *map_mask_name,
+              struct dt_device_node **target, uint32_t *id_out)
+{
+    uint32_t map_mask, masked_id, map_len;
+    const __be32 *map = NULL;
+
+    if ( !np || !map_name || (!target && !id_out) )
+        return -EINVAL;
+
+    map = dt_get_property(np, map_name, &map_len);
+    if ( !map )
+    {
+        if ( target )
+            return -ENODEV;
+
+        /* Otherwise, no map implies no translation */
+        *id_out = id;
+        return 0;
+    }
+
+    if ( !map_len || (map_len % (4 * sizeof(*map))) )
+    {
+        printk(XENLOG_ERR "%s(): %s: Error: Bad %s length: %u\n", __func__,
+               np->full_name, map_name, map_len);
+        return -EINVAL;
+    }
+
+    /* The default is to select all bits. */
+    map_mask = GENMASK(31, 0);
+
+    /*
+     * Can be overridden by "{iommu,msi}-map-mask" property.
+     * If dt_property_read_u32() fails, the default is used.
+     */
+    if ( map_mask_name )
+        dt_property_read_u32(np, map_mask_name, &map_mask);
+
+    masked_id = map_mask & id;
+    for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4 )
+    {
+        struct dt_device_node *phandle_node;
+        uint32_t id_base = be32_to_cpup(map + 0);
+        uint32_t phandle = be32_to_cpup(map + 1);
+        uint32_t out_base = be32_to_cpup(map + 2);
+        uint32_t id_len = be32_to_cpup(map + 3);
+
+        if ( id_base & ~map_mask )
+        {
+            printk(XENLOG_ERR "%s(): %s: Invalid %s translation - %s-mask (0x%"PRIx32") ignores id-base (0x%"PRIx32")\n",
+                   __func__, np->full_name, map_name, map_name, map_mask,
+                   id_base);
+            return -EFAULT;
+        }
+
+        if ( (masked_id < id_base) || (masked_id >= (id_base + id_len)) )
+            continue;
+
+        phandle_node = dt_find_node_by_phandle(phandle);
+        if ( !phandle_node )
+            return -ENODEV;
+
+        if ( target )
+        {
+            if ( !*target )
+                *target = phandle_node;
+
+            if ( *target != phandle_node )
+                continue;
+        }
+
+        if ( id_out )
+            *id_out = masked_id - id_base + out_base;
+
+        dprintk(XENLOG_DEBUG, "%s: %s, using mask %08"PRIx32", id-base: %08"PRIx32", out-base: %08"PRIx32", length: %08"PRIx32", id: %08"PRIx32" -> %08"PRIx32"\n",
+               np->full_name, map_name, map_mask, id_base, out_base, id_len, id,
+               masked_id - id_base + out_base);
+        return 0;
+    }
+
+    dprintk(XENLOG_DEBUG, "%s: no %s translation for id 0x%"PRIx32" on %s\n",
+           np->full_name, map_name, id,
+           (target && *target) ? (*target)->full_name : NULL);
+
+    if ( id_out )
+        *id_out = id;
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/drivers/passthrough/device_tree.c b/xen/drivers/passthrough/device_tree.c
index 159ace9856c9..5ee81132cb4d 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -161,6 +161,48 @@ static int iommu_dt_xlate(struct device *dev,
     return ops->dt_xlate(dev, iommu_spec);
 }
 
+#ifdef CONFIG_HAS_PCI
+int iommu_add_dt_pci_sideband_ids(struct pci_dev *pdev)
+{
+    const struct iommu_ops *ops = iommu_get_ops();
+    struct dt_phandle_args iommu_spec = { .args_count = 1 };
+    struct device *dev = pci_to_dev(pdev);
+    const struct dt_device_node *np;
+    int rc;
+
+    if ( !iommu_enabled )
+        return NO_IOMMU;
+
+    if ( !ops )
+        return -EINVAL;
+
+    if ( dev_iommu_fwspec_get(dev) )
+        return -EEXIST;
+
+    np = pci_find_host_bridge_node(pdev);
+    if ( !np )
+        return -ENODEV;
+
+    /*
+     * According to the Documentation/devicetree/bindings/pci/pci-iommu.txt
+     * from Linux.
+     */
+    rc = dt_map_id(np, PCI_BDF(pdev->bus, pdev->devfn), "iommu-map",
+                   "iommu-map-mask", &iommu_spec.np, iommu_spec.args);
+    if ( rc )
+        return (rc == -ENODEV) ? NO_IOMMU : rc;
+
+    rc = iommu_dt_xlate(dev, &iommu_spec);
+    if ( rc < 0 )
+    {
+        iommu_fwspec_free(dev);
+        return -EINVAL;
+    }
+
+    return rc;
+}
+#endif /* CONFIG_HAS_PCI */
+
 int iommu_remove_dt_device(struct dt_device_node *np)
 {
     const struct iommu_ops *ops = iommu_get_ops();
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index a262bba2edaf..14ec3f565976 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -939,6 +939,29 @@ int dt_count_phandle_with_args(const struct dt_device_node *np,
  */
 int dt_get_pci_domain_nr(struct dt_device_node *node);
 
+/**
+ * dt_map_id - Translate an ID through a downstream mapping.
+ * @np: root complex device node.
+ * @id: device ID to map.
+ * @map_name: property name of the map to use.
+ * @map_mask_name: optional property name of the mask to use.
+ * @target: optional pointer to a target device node.
+ * @id_out: optional pointer to receive the translated ID.
+ *
+ * Given a device ID, look up the appropriate implementation-defined
+ * platform ID and/or the target device which receives transactions on that
+ * ID, as per the "iommu-map" and "msi-map" bindings. Either of @target or
+ * @id_out may be NULL if only the other is required. If @target points to
+ * a non-NULL device node pointer, only entries targeting that node will be
+ * matched; if it points to a NULL value, it will receive the device node of
+ * the first matching target phandle, with a reference held.
+ *
+ * Return: 0 on success or a standard error code on failure.
+ */
+int dt_map_id(const struct dt_device_node *np, uint32_t id,
+              const char *map_name, const char *map_mask_name,
+              struct dt_device_node **target, uint32_t *id_out);
+
 struct dt_device_node *dt_find_node_by_phandle(dt_phandle handle);
 
 #ifdef CONFIG_DEVICE_TREE_DEBUG
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 8cd4b9a6bfb2..2f081a8cea62 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -27,6 +27,9 @@
 #include <xen/errno.h>
 #include <public/domctl.h>
 #include <public/hvm/ioreq.h>
+#ifdef CONFIG_ACPI
+#include <asm/acpi.h>
+#endif
 #include <asm/device.h>
 
 TYPE_SAFE(uint64_t, dfn);
@@ -222,7 +225,8 @@ int iommu_dt_domain_init(struct domain *d);
 int iommu_release_dt_devices(struct domain *d);
 
 /*
- * Helper to add master device to the IOMMU using generic IOMMU DT bindings.
+ * Helpers to add master device to the IOMMU using generic (PCI-)IOMMU
+ * DT bindings.
  *
  * Return values:
  *  0 : device is protected by an IOMMU
@@ -231,6 +235,7 @@ int iommu_release_dt_devices(struct domain *d);
  *      (IOMMU is not enabled/present or device is not connected to it).
  */
 int iommu_add_dt_device(struct dt_device_node *np);
+int iommu_add_dt_pci_sideband_ids(struct pci_dev *pdev);
 
 int iommu_do_dt_domctl(struct xen_domctl *domctl, struct domain *d,
                        XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl);
@@ -247,8 +252,25 @@ int iommu_remove_dt_device(struct dt_device_node *np);
 
 #define NO_IOMMU    1
 
+#else /* !HAS_DEVICE_TREE */
+static inline int iommu_add_dt_pci_sideband_ids(struct pci_dev *pdev)
+{
+    return -ENOSYS;
+}
 #endif /* HAS_DEVICE_TREE */
 
+static inline int iommu_add_pci_sideband_ids(struct pci_dev *pdev)
+{
+    int ret = -ENOSYS;
+
+#ifdef CONFIG_ACPI
+    if ( acpi_disabled )
+#endif
+        ret = iommu_add_dt_pci_sideband_ids(pdev);
+
+    return ret;
+}
+
 struct page_info;
 
 /*
