[RFC 3/7] s390/vfio-ap: do not reset queue removed from host config

[Tony Krowiak <akrowiak@linux.ibm.com>]

When a queue is unbound from the vfio_ap device driver, it is reset to
ensure its crypto data is not leaked when it is bound to another device
driver. If the queue is unbound due to the fact that the adapter or domain
was removed from the host's AP configuration, then attempting to reset it
will fail with response code 01 (APID not valid) getting returned from the
reset command. Let's ensure that the queue is assigned to the host's
configuration before resetting it.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Fixes: eeb386aeb5b7 ("s390/vfio-ap: handle config changed and scan complete notification")
Cc: <stable@vger.kernel.org>
---
 drivers/s390/crypto/vfio_ap_ops.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 4e40e226ce62..08d612dfc506 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2125,13 +2125,12 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 	q = dev_get_drvdata(&apdev->device);
 	get_update_locks_for_queue(q);
 	matrix_mdev = q->matrix_mdev;
+	apid = AP_QID_CARD(q->apqn);
+	apqi = AP_QID_QUEUE(q->apqn);
 
 	if (matrix_mdev) {
 		vfio_ap_unlink_queue_fr_mdev(q);
 
-		apid = AP_QID_CARD(q->apqn);
-		apqi = AP_QID_QUEUE(q->apqn);
-
 		/*
 		 * If the queue is assigned to the guest's APCB, then remove
 		 * the adapter's APID from the APCB and hot it into the guest.
@@ -2143,8 +2142,17 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 		}
 	}
 
-	vfio_ap_mdev_reset_queue(q);
-	flush_work(&q->reset_work);
+	/*
+	 * If the queue is not in the host's AP configuration, then resetting
+	 * it will fail with response code 01, (APQN not valid); so, let's make
+	 * sure it is in the host's config.
+	 */
+	if (test_bit_inv(apid, (unsigned long *)matrix_dev->info.apm) &&
+	    test_bit_inv(apqi, (unsigned long *)matrix_dev->info.aqm)) {
+		vfio_ap_mdev_reset_queue(q);
+		flush_work(&q->reset_work);
+	}
+
 	dev_set_drvdata(&apdev->device, NULL);
 	kfree(q);
 	release_update_locks_for_mdev(matrix_mdev);
-- 
2.41.0