s390/vfio-ap: improve reaction to response code 07 from PQAP(AQIC) command

Let's improve the vfio_ap driver's reaction to reception of response code
07 from the PQAP(AQIC) command when enabling interrupts on behalf of a
guest:

* Unregister the guest's ISC before the pages containing the notification
  indicator bytes are unpinned.

* Capture the return code from the kvm_s390_gisc_unregister function and
  log a DBF warning if it fails.
Suggested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20231109164427.460493-4-akrowiak@linux.ibm.comSigned-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

drivers/s390/crypto/vfio_ap_ops.c

@@ -476,8 +476,11 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
 		break;
 	case AP_RESPONSE_OTHERWISE_CHANGED:
 		/* We could not modify IRQ settings: clear new configuration */
+		ret = kvm_s390_gisc_unregister(kvm, isc);
+		if (ret)
+			VFIO_AP_DBF_WARN("%s: kvm_s390_gisc_unregister: rc=%d isc=%d, apqn=%#04x\n",
+					 __func__, ret, isc, q->apqn);
 		vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1);
-		kvm_s390_gisc_unregister(kvm, isc);
 		break;
 	default:
 		pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn,