scsi: ibmvfc: Reinitialize sub-CRQs and perform channel enquiry after LPM

A live partition migration (LPM) results in a CRQ disconnect similar to a
hard reset. In this LPM case the hypervisor mostly preserves the CRQ
transport such that it simply needs to be reenabled. However, the
capabilities may have changed such as fewer channels, or no channels at
all. Further, its possible that there may be sub-CRQ support, but no
channel support. The CRQ reenable path currently doesn't take any of this
into consideration.

For simplicity release and reinitialize sub-CRQs during reenable, and set
do_enquiry and using_channels with the appropriate values to trigger
channel renegotiation.

Link: https://lore.kernel.org/r/20210302230543.9905-6-tyreld@linux.ibm.com
Fixes: 3034ebe2 ("scsi: ibmvfc: Add alloc/dealloc routines for SCSI Sub-CRQ Channels")
Reviewed-by: Brian King <brking@linux.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi/ibmvfc.c

@@ -903,6 +903,9 @@ static int ibmvfc_reenable_crq_queue(struct ibmvfc_host *vhost)
 {
 	int rc = 0;
 	struct vio_dev *vdev = to_vio_dev(vhost->dev);
+	unsigned long flags;
+
+	ibmvfc_release_sub_crqs(vhost);
 
 	/* Re-enable the CRQ */
 	do {
@@ -914,6 +917,15 @@ static int ibmvfc_reenable_crq_queue(struct ibmvfc_host *vhost)
 	if (rc)
 		dev_err(vhost->dev, "Error enabling adapter (rc=%d)\n", rc);
 
+	spin_lock_irqsave(vhost->host->host_lock, flags);
+	spin_lock(vhost->crq.q_lock);
+	vhost->do_enquiry = 1;
+	vhost->using_channels = 0;
+	spin_unlock(vhost->crq.q_lock);
+	spin_unlock_irqrestore(vhost->host->host_lock, flags);
+
+	ibmvfc_init_sub_crqs(vhost);
+
 	return rc;
 }