linux-kernel - [PATCH v16 02/14] s390/vfio-ap: use new AP bus interface to search for queue devices

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Message-Id: <20210510164423.346858-3-akrowiak@linux.ibm.com>
Date:   Mon, 10 May 2021 12:44:11 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     jjherne@...ux.ibm.com, freude@...ux.ibm.com,
        borntraeger@...ibm.com, cohuck@...hat.com, mjrosato@...ux.ibm.com,
        pasic@...ux.ibm.com, alex.williamson@...hat.com,
        kwankhede@...dia.com, fiuczy@...ux.ibm.com,
        Tony Krowiak <akrowiak@...ux.ibm.com>
Subject: [PATCH v16 02/14] s390/vfio-ap: use new AP bus interface to search for queue devices

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@...ux.ibm.com>
Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 757166da947e..8a50aa650b65 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -27,13 +27,6 @@
 static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
 static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
 
-static int match_apqn(struct device *dev, const void *data)
-{
-	struct vfio_ap_queue *q = dev_get_drvdata(dev);
-
-	return (q->apqn == *(int *)(data)) ? 1 : 0;
-}
-
 /**
  * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list
  * @matrix_mdev: the associated mediated matrix
@@ -1253,15 +1246,17 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
 
 static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
 {
-	struct device *dev;
+	struct ap_queue *queue;
 	struct vfio_ap_queue *q = NULL;
 
-	dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
-				 &apqn, match_apqn);
-	if (dev) {
-		q = dev_get_drvdata(dev);
-		put_device(dev);
-	}
+	queue = ap_get_qdev(apqn);
+	if (!queue)
+		return NULL;
+
+	if (queue->ap_dev.device.driver == &matrix_dev->vfio_ap_drv->driver)
+		q = dev_get_drvdata(&queue->ap_dev.device);
+
+	put_device(&queue->ap_dev.device);
 
 	return q;
 }
-- 
2.30.2