Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Tony Krowiak <akrowiak@linux.ibm.com>
To:     linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     jjherne@linux.ibm.com, freude@linux.ibm.com,
        borntraeger@de.ibm.com, cohuck@redhat.com, mjrosato@linux.ibm.com,
        pasic@linux.ibm.com, alex.williamson@redhat.com,
        kwankhede@nvidia.com, fiuczy@linux.ibm.com
Subject: [PATCH 3/7] s390/vfio_ap: use TAPQ to verify reset in progress completes
Date:   Tue, 13 Dec 2022 10:44:33 -0500
Message-Id: <20221213154437.15480-4-akrowiak@linux.ibm.com>
In-Reply-To: <20221213154437.15480-1-akrowiak@linux.ibm.com>
References: <20221213154437.15480-1-akrowiak@linux.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

To eliminate the repeated calls to the PQAP(ZAPQ) function to verify that
a reset in progress completed successfully and ensure that error response
codes get appropriately logged, let's call the apq_reset_check() function
when the ZAPQ response code indicates that a reset that is already in
progress.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index a5530a46cf31..5bf2d93ae8af 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -33,7 +33,7 @@
 static int vfio_ap_mdev_reset_queues(struct ap_queue_table *qtable);
 static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
 static const struct vfio_device_ops vfio_ap_matrix_dev_ops;
-static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q, unsigned int retry);
+static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q);
 
 /**
  * get_update_locks_for_kvm: Acquire the locks required to dynamically update a
@@ -1632,8 +1632,7 @@ static int apq_reset_check(struct vfio_ap_queue *q)
 	return ret;
 }
 
-static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
-				    unsigned int retry)
+static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
 {
 	struct ap_queue_status status;
 	int ret;
@@ -1648,12 +1647,15 @@ static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
 		ret = 0;
 		break;
 	case AP_RESPONSE_RESET_IN_PROGRESS:
-		if (retry--) {
-			msleep(20);
-			goto retry_zapq;
-		}
-		ret = -EBUSY;
-		break;
+		/*
+		 * There is a reset issued by another process in progress. Let's wait
+		 * for that to complete. Since we have no idea whether it was a RAPQ or
+		 * ZAPQ, then if it completes successfully, let's issue the ZAPQ.
+		 */
+		ret = apq_reset_check(q);
+		if (ret)
+			break;
+		goto retry_zapq;
 	case AP_RESPONSE_Q_NOT_AVAIL:
 	case AP_RESPONSE_DECONFIGURED:
 	case AP_RESPONSE_CHECKSTOPPED:
@@ -1688,7 +1690,7 @@ static int vfio_ap_mdev_reset_queues(struct ap_queue_table *qtable)
 	struct vfio_ap_queue *q;
 
 	hash_for_each(qtable->queues, loop_cursor, q, mdev_qnode) {
-		ret = vfio_ap_mdev_reset_queue(q, 1);
+		ret = vfio_ap_mdev_reset_queue(q);
 		/*
 		 * Regardless whether a queue turns out to be busy, or
 		 * is not operational, we need to continue resetting
@@ -1931,7 +1933,7 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 		}
 	}
 
-	vfio_ap_mdev_reset_queue(q, 1);
+	vfio_ap_mdev_reset_queue(q);
 	dev_set_drvdata(&apdev->device, NULL);
 	kfree(q);
 	release_update_locks_for_mdev(matrix_mdev);
-- 
2.31.1