diff --git a/xen/drivers/Kconfig b/xen/drivers/Kconfig
index db94393f47..780490cf8e 100644
--- a/xen/drivers/Kconfig
+++ b/xen/drivers/Kconfig
@@ -15,4 +15,8 @@ source "drivers/video/Kconfig"
 config HAS_VPCI
 	bool
 
+config HAS_VPCI_GUEST_SUPPORT
+	bool
+	depends on HAS_VPCI
+
 endmenu
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index 8865c1580e..c92f2d7bc3 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -36,6 +36,49 @@ extern vpci_register_init_t *const __start_vpci_array[];
 extern vpci_register_init_t *const __end_vpci_array[];
 #define NUM_VPCI_INIT (__end_vpci_array - __start_vpci_array)
 
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+static int add_virtual_device(struct pci_dev *pdev)
+{
+    struct domain *d = pdev->domain;
+    unsigned int new_dev_number;
+
+    if ( is_hardware_domain(d) )
+        return 0;
+
+    ASSERT(rw_is_write_locked(&pdev->domain->pci_lock));
+
+    /*
+     * Each PCI bus supports 32 devices/slots at max or up to 256 when
+     * there are multi-function ones which are not yet supported.
+     */
+    if ( pdev->info.is_extfn && !pdev->info.is_virtfn )
+    {
+        gdprintk(XENLOG_ERR, "%pp: only function 0 passthrough supported\n",
+                 &pdev->sbdf);
+        return -EOPNOTSUPP;
+    }
+    new_dev_number = find_first_zero_bit(d->vpci_dev_assigned_map,
+                                         VPCI_MAX_VIRT_DEV);
+    if ( new_dev_number == VPCI_MAX_VIRT_DEV )
+        return -ENOSPC;
+
+    __set_bit(new_dev_number, &d->vpci_dev_assigned_map);
+
+    /*
+     * Both segment and bus number are 0:
+     *  - we emulate a single host bridge for the guest, e.g. segment 0
+     *  - with bus 0 the virtual devices are seen as embedded
+     *    endpoints behind the root complex
+     *
+     * TODO: add support for multi-function devices.
+     */
+    pdev->vpci->guest_sbdf = PCI_SBDF(0, 0, new_dev_number, 0);
+
+    return 0;
+}
+
+#endif /* CONFIG_HAS_VPCI_GUEST_SUPPORT */
+
 void vpci_deassign_device(struct pci_dev *pdev)
 {
     unsigned int i;
@@ -45,6 +88,12 @@ void vpci_deassign_device(struct pci_dev *pdev)
     if ( !has_vpci(pdev->domain) || !pdev->vpci )
         return;
 
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+    if ( pdev->vpci->guest_sbdf.sbdf != ~0 )
+        __clear_bit(pdev->vpci->guest_sbdf.dev,
+                    &pdev->domain->vpci_dev_assigned_map);
+#endif
+
     spin_lock(&pdev->vpci->lock);
     while ( !list_empty(&pdev->vpci->handlers) )
     {
@@ -101,6 +150,13 @@ int vpci_assign_device(struct pci_dev *pdev)
     INIT_LIST_HEAD(&pdev->vpci->handlers);
     spin_lock_init(&pdev->vpci->lock);
 
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+    pdev->vpci->guest_sbdf.sbdf = ~0;
+    rc = add_virtual_device(pdev);
+    if ( rc )
+        goto out;
+#endif
+
     for ( i = 0; i < NUM_VPCI_INIT; i++ )
     {
         rc = __start_vpci_array[i](pdev);
@@ -108,6 +164,7 @@ int vpci_assign_device(struct pci_dev *pdev)
             break;
     }
 
+ out: __maybe_unused;
     if ( rc )
         vpci_deassign_device(pdev);
 
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 57391e74b6..84e608f670 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -462,6 +462,14 @@ struct domain
 #ifdef CONFIG_HAS_PCI
     struct list_head pdev_list;
     rwlock_t pci_lock;
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+    /*
+     * The bitmap which shows which device numbers are already used by the
+     * virtual PCI bus topology and is used to assign a unique SBDF to the
+     * next passed through virtual PCI device.
+     */
+    DECLARE_BITMAP(vpci_dev_assigned_map, VPCI_MAX_VIRT_DEV);
+#endif
 #endif
 
 #ifdef CONFIG_HAS_PASSTHROUGH
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index a50dad6968..6a06267ef2 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -21,6 +21,13 @@ typedef int vpci_register_init_t(struct pci_dev *dev);
 
 #define VPCI_ECAM_BDF(addr)     (((addr) & 0x0ffff000) >> 12)
 
+/*
+ * Maximum number of devices supported by the virtual bus topology:
+ * each PCI bus supports 32 devices/slots at max or up to 256 when
+ * there are multi-function ones which are not yet supported.
+ */
+#define VPCI_MAX_VIRT_DEV       (PCI_SLOT(~0) + 1)
+
 #define REGISTER_VPCI_INIT(x, p)                \
   static vpci_register_init_t *const x##_entry  \
                __used_section(".data.vpci." p) = x
@@ -155,6 +162,10 @@ struct vpci {
             struct vpci_arch_msix_entry arch;
         } entries[];
     } *msix;
+#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
+    /* Guest SBDF of the device. */
+    pci_sbdf_t guest_sbdf;
+#endif
 #endif
 };
 
