diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index 09ec846fe01d..18b713a616de 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -4,7 +4,7 @@
  *
  * Module interface and handling of zfcp data structures.
  *
- * Copyright IBM Corp. 2002, 2018
+ * Copyright IBM Corp. 2002, 2020
  */
 
 /*
@@ -415,8 +415,7 @@ struct zfcp_adapter *zfcp_adapter_enqueue(struct ccw_device *ccw_device)
 
 	adapter->stat_read_buf_num = FSF_STATUS_READS_RECOM;
 
-	if (!zfcp_scsi_adapter_register(adapter))
-		return adapter;
+	return adapter;
 
 failed:
 	zfcp_adapter_unregister(adapter);
diff --git a/drivers/s390/scsi/zfcp_diag.h b/drivers/s390/scsi/zfcp_diag.h
index b9c93d15f67c..3852367f15f6 100644
--- a/drivers/s390/scsi/zfcp_diag.h
+++ b/drivers/s390/scsi/zfcp_diag.h
@@ -4,7 +4,7 @@
  *
  * Definitions for handling diagnostics in the the zfcp device driver.
  *
- * Copyright IBM Corp. 2018
+ * Copyright IBM Corp. 2018, 2020
  */
 
 #ifndef ZFCP_DIAG_H
@@ -56,11 +56,11 @@ struct zfcp_diag_adapter {
 
 	unsigned long	max_age;
 
-	struct {
+	struct zfcp_diag_adapter_port_data {
 		struct zfcp_diag_header		header;
 		struct fsf_qtcb_bottom_port	data;
 	} port_data;
-	struct {
+	struct zfcp_diag_adapter_config_data {
 		struct zfcp_diag_header		header;
 		struct fsf_qtcb_bottom_config	data;
 	} config_data;
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index 283bcb985655..db320dab1fee 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -14,6 +14,7 @@
 #include <linux/bug.h>
 #include "zfcp_ext.h"
 #include "zfcp_reqlist.h"
+#include "zfcp_diag.h"
 
 #define ZFCP_MAX_ERPS                   3
 
@@ -804,6 +805,59 @@ static enum zfcp_erp_act_result zfcp_erp_adapter_strategy_open_fsf_xport(
 	return ZFCP_ERP_SUCCEEDED;
 }
 
+static enum zfcp_erp_act_result
+zfcp_erp_adapter_strategy_alloc_shost(struct zfcp_adapter *const adapter)
+{
+	struct zfcp_diag_adapter_config_data *const config_data =
+		&adapter->diagnostics->config_data;
+	struct zfcp_diag_adapter_port_data *const port_data =
+		&adapter->diagnostics->port_data;
+	unsigned long flags;
+	int rc;
+
+	rc = zfcp_scsi_adapter_register(adapter);
+	if (rc == -EEXIST)
+		return ZFCP_ERP_SUCCEEDED;
+	else if (rc)
+		return ZFCP_ERP_FAILED;
+
+	/*
+	 * We allocated the shost for the first time. Before it was NULL,
+	 * and so we deferred all updates in the xconf- and xport-data
+	 * handlers. We need to make up for that now, and make all the updates
+	 * that would have been done before.
+	 *
+	 * We can be sure that xconf- and xport-data succeeded, because
+	 * otherwise this function is not called. But they might have been
+	 * incomplete.
+	 */
+
+	spin_lock_irqsave(&config_data->header.access_lock, flags);
+	zfcp_scsi_shost_update_config_data(adapter, &config_data->data,
+					   !!config_data->header.incomplete);
+	spin_unlock_irqrestore(&config_data->header.access_lock, flags);
+
+	if (adapter->adapter_features & FSF_FEATURE_HBAAPI_MANAGEMENT) {
+		spin_lock_irqsave(&port_data->header.access_lock, flags);
+		zfcp_scsi_shost_update_port_data(adapter, &port_data->data);
+		spin_unlock_irqrestore(&port_data->header.access_lock, flags);
+	}
+
+	/*
+	 * There is a remote possibility that the 'Exchange Port Data' request
+	 * reports a different connectivity status than 'Exchange Config Data'.
+	 * But any change to the connectivity status of the local optic that
+	 * happens after the initial xconf request is expected to be reported
+	 * to us, as soon as we post Status Read Buffers to the FCP channel
+	 * firmware after this function. So any resulting inconsistency will
+	 * only be momentary.
+	 */
+	if (config_data->header.incomplete)
+		zfcp_fsf_fc_host_link_down(adapter);
+
+	return ZFCP_ERP_SUCCEEDED;
+}
+
 static enum zfcp_erp_act_result zfcp_erp_adapter_strategy_open_fsf(
 	struct zfcp_erp_action *act)
 {
@@ -813,6 +867,10 @@ static enum zfcp_erp_act_result zfcp_erp_adapter_strategy_open_fsf(
 	if (zfcp_erp_adapter_strategy_open_fsf_xport(act) == ZFCP_ERP_FAILED)
 		return ZFCP_ERP_FAILED;
 
+	if (zfcp_erp_adapter_strategy_alloc_shost(act->adapter) ==
+	    ZFCP_ERP_FAILED)
+		return ZFCP_ERP_FAILED;
+
 	zfcp_erp_adapter_strategy_open_ptp_port(act->adapter);
 
 	if (mempool_resize(act->adapter->pool.sr_data,
diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h
index 5dc9bdc5803f..3ef5d74331c3 100644
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -135,6 +135,7 @@ extern int zfcp_fsf_send_els(struct zfcp_adapter *, u32,
 			     struct zfcp_fsf_ct_els *, unsigned int);
 extern int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *);
 extern void zfcp_fsf_req_free(struct zfcp_fsf_req *);
+extern void zfcp_fsf_fc_host_link_down(struct zfcp_adapter *adapter);
 extern struct zfcp_fsf_req *zfcp_fsf_fcp_task_mgmt(struct scsi_device *sdev,
 						   u8 tm_flags);
 extern struct zfcp_fsf_req *zfcp_fsf_abort_fcp_cmnd(struct scsi_cmnd *);
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 8c4b690e329e..c795f22249d8 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -120,7 +120,7 @@ static void zfcp_fsf_status_read_port_closed(struct zfcp_fsf_req *req)
 	read_unlock_irqrestore(&adapter->port_list_lock, flags);
 }
 
-static void zfcp_fsf_fc_host_link_down(struct zfcp_adapter *adapter)
+void zfcp_fsf_fc_host_link_down(struct zfcp_adapter *adapter)
 {
 	struct Scsi_Host *shost = adapter->scsi_host;
 
diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c
index f98e4015a0ed..d58bf79892f2 100644
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -451,26 +451,39 @@ static struct scsi_host_template zfcp_scsi_host_template = {
 };
 
 /**
- * zfcp_scsi_adapter_register - Register SCSI and FC host with SCSI midlayer
+ * zfcp_scsi_adapter_register() - Allocate and register SCSI and FC host with
+ *				  SCSI midlayer
  * @adapter: The zfcp adapter to register with the SCSI midlayer
+ *
+ * Allocates the SCSI host object for the given adapter, sets basic properties
+ * (such as the transport template, QDIO limits, ...), and registers it with
+ * the midlayer.
+ *
+ * During registration with the midlayer the corresponding FC host object for
+ * the referenced transport class is also implicitely allocated.
+ *
+ * Upon success adapter->scsi_host is set, and upon failure it remains NULL. If
+ * adapter->scsi_host is already set, nothing is done.
+ *
+ * Return:
+ * * 0	     - Allocation and registration was successful
+ * * -EEXIST - SCSI and FC host did already exist, nothing was done, nothing
+ *	       was changed
+ * * -EIO    - Allocation or registration failed
  */
 int zfcp_scsi_adapter_register(struct zfcp_adapter *adapter)
 {
 	struct ccw_dev_id dev_id;
 
 	if (adapter->scsi_host)
-		return 0;
+		return -EEXIST;
 
 	ccw_device_get_id(adapter->ccw_device, &dev_id);
 	/* register adapter as SCSI host with mid layer of SCSI stack */
 	adapter->scsi_host = scsi_host_alloc(&zfcp_scsi_host_template,
 					     sizeof (struct zfcp_adapter *));
-	if (!adapter->scsi_host) {
-		dev_err(&adapter->ccw_device->dev,
-			"Registering the FCP device with the "
-			"SCSI stack failed\n");
-		return -EIO;
-	}
+	if (!adapter->scsi_host)
+		goto err_out;
 
 	/* tell the SCSI stack some characteristics of this adapter */
 	adapter->scsi_host->max_id = 511;
@@ -480,14 +493,23 @@ int zfcp_scsi_adapter_register(struct zfcp_adapter *adapter)
 	adapter->scsi_host->max_cmd_len = 16; /* in struct fcp_cmnd */
 	adapter->scsi_host->transportt = zfcp_scsi_transport_template;
 
+	/* make all basic properties known at registration time */
+	zfcp_qdio_shost_update(adapter, adapter->qdio);
+	zfcp_scsi_set_prot(adapter);
+
 	adapter->scsi_host->hostdata[0] = (unsigned long) adapter;
 
 	if (scsi_add_host(adapter->scsi_host, &adapter->ccw_device->dev)) {
 		scsi_host_put(adapter->scsi_host);
-		return -EIO;
+		goto err_out;
 	}
 
 	return 0;
+err_out:
+	adapter->scsi_host = NULL;
+	dev_err(&adapter->ccw_device->dev,
+		"Registering the FCP device with the SCSI stack failed\n");
+	return -EIO;
 }
 
 /**