diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c
index 5d77acbd1c87..6a8da1b742ae 100644
--- a/arch/s390/pci/pci_bus.c
+++ b/arch/s390/pci/pci_bus.c
@@ -145,9 +145,6 @@ int zpci_bus_scan_bus(struct zpci_bus *zbus)
 	struct zpci_dev *zdev;
 	int devfn, rc, ret = 0;
 
-	if (!zbus->function[0])
-		return 0;
-
 	for (devfn = 0; devfn < ZPCI_FUNCTIONS_PER_BUS; devfn++) {
 		zdev = zbus->function[devfn];
 		if (zdev && zdev->state == ZPCI_FN_STATE_CONFIGURED) {
@@ -184,26 +181,26 @@ void zpci_bus_scan_busses(void)
 
 /* zpci_bus_create_pci_bus - Create the PCI bus associated with this zbus
  * @zbus: the zbus holding the zdevices
- * @f0: function 0 of the bus
+ * @fr: PCI root function that will determine the bus's domain, and bus speeed
  * @ops: the pci operations
  *
- * Function zero is taken as a parameter as this is used to determine the
- * domain, multifunction property and maximum bus speed of the entire bus.
+ * The PCI function @fr determines the domain (its UID), multifunction property
+ * and maximum bus speed of the entire bus.
  *
  * Return: 0 on success, an error code otherwise
  */
-static int zpci_bus_create_pci_bus(struct zpci_bus *zbus, struct zpci_dev *f0, struct pci_ops *ops)
+static int zpci_bus_create_pci_bus(struct zpci_bus *zbus, struct zpci_dev *fr, struct pci_ops *ops)
 {
 	struct pci_bus *bus;
 	int domain;
 
-	domain = zpci_alloc_domain((u16)f0->uid);
+	domain = zpci_alloc_domain((u16)fr->uid);
 	if (domain < 0)
 		return domain;
 
 	zbus->domain_nr = domain;
-	zbus->multifunction = f0->rid_available;
-	zbus->max_bus_speed = f0->max_bus_speed;
+	zbus->multifunction = fr->rid_available;
+	zbus->max_bus_speed = fr->max_bus_speed;
 
 	/*
 	 * Note that the zbus->resources are taken over and zbus->resources
@@ -303,47 +300,6 @@ void pcibios_bus_add_device(struct pci_dev *pdev)
 	}
 }
 
-/* zpci_bus_create_hotplug_slots - Add hotplug slot(s) for device added to bus
- * @zdev: the zPCI device that was newly added
- *
- * Add the hotplug slot(s) for the newly added PCI function. Normally this is
- * simply the slot for the function itself. If however we are adding the
- * function 0 on a zbus, it might be that we already registered functions on
- * that zbus but could not create their hotplug slots yet so add those now too.
- *
- * Return: 0 on success, an error code otherwise
- */
-static int zpci_bus_create_hotplug_slots(struct zpci_dev *zdev)
-{
-	struct zpci_bus *zbus = zdev->zbus;
-	int devfn, rc = 0;
-
-	rc = zpci_init_slot(zdev);
-	if (rc)
-		return rc;
-	zdev->has_hp_slot = 1;
-
-	if (zdev->devfn == 0 && zbus->multifunction) {
-		/* Now that function 0 is there we can finally create the
-		 * hotplug slots for those functions with devfn != 0 that have
-		 * been parked in zbus->function[] waiting for us to be able to
-		 * create the PCI bus.
-		 */
-		for  (devfn = 1; devfn < ZPCI_FUNCTIONS_PER_BUS; devfn++) {
-			zdev = zbus->function[devfn];
-			if (zdev && !zdev->has_hp_slot) {
-				rc = zpci_init_slot(zdev);
-				if (rc)
-					return rc;
-				zdev->has_hp_slot = 1;
-			}
-		}
-
-	}
-
-	return rc;
-}
-
 static int zpci_bus_add_device(struct zpci_bus *zbus, struct zpci_dev *zdev)
 {
 	int rc = -EINVAL;
@@ -352,21 +308,19 @@ static int zpci_bus_add_device(struct zpci_bus *zbus, struct zpci_dev *zdev)
 		pr_err("devfn %04x is already assigned\n", zdev->devfn);
 		return rc;
 	}
+
 	zdev->zbus = zbus;
 	zbus->function[zdev->devfn] = zdev;
 	zpci_nb_devices++;
 
-	if (zbus->bus) {
-		if (zbus->multifunction && !zdev->rid_available) {
-			WARN_ONCE(1, "rid_available not set for multifunction\n");
-			goto error;
-		}
-
-		zpci_bus_create_hotplug_slots(zdev);
-	} else {
-		/* Hotplug slot will be created once function 0 appears */
-		zbus->multifunction = 1;
+	if (zbus->multifunction && !zdev->rid_available) {
+		WARN_ONCE(1, "rid_available not set for multifunction\n");
+		goto error;
 	}
+	rc = zpci_init_slot(zdev);
+	if (rc)
+		goto error;
+	zdev->has_hp_slot = 1;
 
 	return 0;
 
@@ -400,7 +354,11 @@ int zpci_bus_device_register(struct zpci_dev *zdev, struct pci_ops *ops)
 			return -ENOMEM;
 	}
 
-	if (zdev->devfn == 0) {
+	if (!zbus->bus) {
+		/* The UID of the first PCI function registered with a zpci_bus
+		 * is used as the domain number for that bus. Currently there
+		 * is exactly one zpci_bus per domain.
+		 */
 		rc = zpci_bus_create_pci_bus(zbus, zdev, ops);
 		if (rc)
 			goto error;