[PATCH v1 5/6] s390/vfio-ap: reset queues associated with adapter for queue unbound from driver

[Tony Krowiak]

When a queue is unbound from the vfio_ap device driver, if that queue is
assigned to a guest's AP configuration, its associated adapter is removed
because queues are defined to a guest via a matrix of adapters and
domains; so, it is not possible to remove a single queue.

If an adapter is removed from the guest's AP configuration, all associated
queues must be reset to prevent leaking crypto data should any of them be
assigned to a different guest or device driver. The one caveat is that if
the queue is being removed because the adapter or domain has been removed
from the host's AP configuration, then an attempt to reset the queue will
fail with response code 01, AP-queue number not valid; so resetting these
queues should be skipped.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Fixes: 09d31ff78793 ("s390/vfio-ap: hot plug/unplug of AP devices when probed/removed")
Cc: <stable@xxxxxxxxxxxxxxx>
---
 drivers/s390/crypto/vfio_ap_ops.c | 39 ++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index f08321385058..5db11d50b4b0 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -2187,6 +2187,23 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 	return ret;
 }
 
+static void reset_queues_for_apid(struct ap_matrix_mdev *matrix_mdev,
+				  unsigned long apid)
+{
+	DECLARE_BITMAP(apm_reset, AP_DEVICES);
+
+	/*
+	 * If the adapter is not in the host's AP configuration, then resetting
+	 * any queue for that adapter will fail with response code 01, (APQN not
+	 * valid).
+	 */
+	if (test_bit_inv(apid, (unsigned long *)matrix_dev->info.apm)) {
+		bitmap_clear(apm_reset, 0, AP_DEVICES);
+		set_bit_inv(apid, apm_reset);
+		reset_queues_for_apids(matrix_mdev, apm_reset);
+	}
+}
+
 void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 {
 	unsigned long apid, apqi;
@@ -2199,24 +2216,28 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 	matrix_mdev = q->matrix_mdev;
 
 	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.
-		 */
+		/* If the queue is assigned to the guest's AP configuration */
 		if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm) &&
 		    test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) {
+			/*
+			 * Since the queues are defined via a matrix of adapters
+			 * and domains, it is not possible to hot unplug a
+			 * single queue; so, let's unplug the adapter.
+			 */
 			clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm);
 			vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+			reset_queues_for_apid(matrix_mdev, apid);
+			goto done;
 		}
 	}
 
 	vfio_ap_mdev_reset_queue(q);
 	flush_work(&q->reset_work);
+
+done:
+	if (matrix_mdev)
+		vfio_ap_unlink_queue_fr_mdev(q);
+
 	dev_set_drvdata(&apdev->device, NULL);
 	kfree(q);
 	release_update_locks_for_mdev(matrix_mdev);
-- 
2.43.0