[PATCH v12 03/17] 390/vfio-ap: use new AP bus interface to search for queue devices

[Tony Krowiak <akrowiak@xxxxxxxxxxxxx>]

This patch refactors the vfio_ap device driver to use the AP bus's
ap_get_qdev() function to retrieve the vfio_ap_queue struct containing
information about a queue that is bound to the vfio_ap device driver.
The bus's ap_get_qdev() function retrieves the queue device from a
hashtable keyed by APQN. This is much more efficient than looping over
the list of devices attached to the AP bus by several orders of
magnitude.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
---
 drivers/s390/crypto/vfio_ap_ops.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 31e39c1f6e56..8e6972495daa 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -33,36 +33,39 @@ static int match_apqn(struct device *dev, const void *data)
 	return (q->apqn == *(int *)(data)) ? 1 : 0;
 }
 
+
 /**
- * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list
+ * vfio_ap_get_queue: Retrieve a queue with a specific APQN.
  * @matrix_mdev: the associated mediated matrix
  * @apqn: The queue APQN
  *
- * Retrieve a queue with a specific APQN from the list of the
- * devices of the vfio_ap_drv.
- * Verify that the APID and the APQI are set in the matrix.
+ * Retrieve a queue with a specific APQN from the AP queue devices attached to
+ * the AP bus.
  *
- * Returns the pointer to the associated vfio_ap_queue
+ * Returns the pointer to the vfio_ap_queue with the specified APQN, or NULL.
  */
 static struct vfio_ap_queue *vfio_ap_get_queue(
 					struct ap_matrix_mdev *matrix_mdev,
 					int apqn)
 {
-	struct vfio_ap_queue *q;
-	struct device *dev;
+	struct ap_queue *queue;
+	struct vfio_ap_queue *q = NULL;
 
 	if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm))
 		return NULL;
 	if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm))
 		return NULL;
 
-	dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
-				 &apqn, match_apqn);
-	if (!dev)
+	queue = ap_get_qdev(apqn);
+	if (!queue)
 		return NULL;
-	q = dev_get_drvdata(dev);
-	q->matrix_mdev = matrix_mdev;
-	put_device(dev);
+
+	put_device(&queue->ap_dev.device);
+
+	if (queue->ap_dev.device.driver == &matrix_dev->vfio_ap_drv->driver) {
+		q = dev_get_drvdata(&queue->ap_dev.device);
+		q->matrix_mdev = matrix_mdev;
+	}
 
 	return q;
 }
-- 
2.21.1