[PATCH v20 13/20] s390/vfio-ap: hot plug/unplug of AP devices when probed/removed

[Tony Krowiak]

When an AP queue device is probed or removed, if the mediated device is
attached to a KVM guest, the mediated device's adapter, domain and
control domain bitmaps must be filtered to update the guest's APCB and if
any changes are detected, the guest's APCB must then be hot plugged into
the guest to reflect those changes to the guest.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reviewed-by: Jason J. Herne <jjherne@xxxxxxxxxxxxx>
---
 drivers/s390/crypto/vfio_ap_ops.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 93e932458590..090e033cff69 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1782,9 +1782,11 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 
 	if (matrix_mdev) {
 		vfio_ap_mdev_link_queue(matrix_mdev, q);
-		vfio_ap_mdev_filter_matrix(matrix_mdev->matrix.apm,
-					   matrix_mdev->matrix.aqm,
-					   matrix_mdev);
+
+		if (vfio_ap_mdev_filter_matrix(matrix_mdev->matrix.apm,
+					       matrix_mdev->matrix.aqm,
+					       matrix_mdev))
+			vfio_ap_mdev_update_guest_apcb(matrix_mdev);
 	}
 	dev_set_drvdata(&apdev->device, q);
 	release_update_locks_for_mdev(matrix_mdev);
@@ -1794,7 +1796,7 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 
 void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 {
-	unsigned long apid;
+	unsigned long apid, apqi;
 	struct vfio_ap_queue *q;
 	struct ap_matrix_mdev *matrix_mdev;
 
@@ -1807,8 +1809,17 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 		vfio_ap_unlink_queue_fr_mdev(q);
 
 		apid = AP_QID_CARD(q->apqn);
-		if (test_bit_inv(apid, q->matrix_mdev->shadow_apcb.apm))
-			clear_bit_inv(apid, q->matrix_mdev->shadow_apcb.apm);
+		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 (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm) &&
+		    test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) {
+			clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm);
+			vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+		}
 	}
 
 	vfio_ap_mdev_reset_queue(q, 1);
-- 
2.35.3