[PATCH v8 05/16] s390/vfio-ap: implement in-use callback for vfio_ap driver

[Tony Krowiak <akrowiak@linux.ibm.com>]

Let's implement the callback to indicate when an APQN
is in use by the vfio_ap device driver. The callback is
invoked whenever a change to the apmask or aqmask would
result in one or more queue devices being removed from the driver. The
vfio_ap device driver will indicate a resource is in use
if the APQN of any of the queue devices to be removed are assigned to
any of the matrix mdevs under the driver's control.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_drv.c     |  1 +
 drivers/s390/crypto/vfio_ap_ops.c     | 68 ++++++++++++++++++++-------
 drivers/s390/crypto/vfio_ap_private.h |  2 +
 3 files changed, 53 insertions(+), 18 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 59233cf7419d..86fc83701e05 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -173,6 +173,7 @@ static int __init vfio_ap_init(void)
 	memset(&vfio_ap_drv, 0, sizeof(vfio_ap_drv));
 	vfio_ap_drv.probe = vfio_ap_queue_dev_probe;
 	vfio_ap_drv.remove = vfio_ap_queue_dev_remove;
+	vfio_ap_drv.in_use = vfio_ap_mdev_resource_in_use;
 	vfio_ap_drv.ids = ap_queue_ids;
 
 	ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 21b98a392f36..2eebb2b6d2d4 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -501,18 +501,36 @@ vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev,
 	return 0;
 }
 
+#define MDEV_SHARING_ERR "Userspace may not re-assign queue %02lx.%04lx " \
+			 "already assigned to %s"
+
+static void vfio_ap_mdev_log_sharing_err(const char *mdev_name,
+					 unsigned long *apm,
+					 unsigned long *aqm)
+{
+	unsigned long apid, apqi;
+
+	for_each_set_bit_inv(apid, apm, AP_DEVICES)
+		for_each_set_bit_inv(apqi, aqm, AP_DOMAINS)
+			pr_err(MDEV_SHARING_ERR, apid, apqi, mdev_name);
+}
+
 /**
  * vfio_ap_mdev_verify_no_sharing
  *
  * Verifies that the APQNs derived from the cross product of the AP adapter IDs
- * and AP queue indexes comprising the AP matrix are not configured for another
+ * and AP queue indexes comprising an AP matrix are not assigned to another
  * mediated device. AP queue sharing is not allowed.
  *
  * @matrix_mdev: the mediated matrix device
+ * @mdev_apm: mask indicating the APIDs of the APQNs to be verified
+ * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified
  *
  * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE.
  */
-static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
+static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev,
+					  unsigned long *mdev_apm,
+					  unsigned long *mdev_aqm)
 {
 	struct ap_matrix_mdev *lstdev;
 	DECLARE_BITMAP(apm, AP_DEVICES);
@@ -529,14 +547,15 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
 		 * We work on full longs, as we can only exclude the leftover
 		 * bits in non-inverse order. The leftover is all zeros.
 		 */
-		if (!bitmap_and(apm, matrix_mdev->matrix.apm,
-				lstdev->matrix.apm, AP_DEVICES))
+		if (!bitmap_and(apm, mdev_apm, lstdev->matrix.apm, AP_DEVICES))
 			continue;
 
-		if (!bitmap_and(aqm, matrix_mdev->matrix.aqm,
-				lstdev->matrix.aqm, AP_DOMAINS))
+		if (!bitmap_and(aqm, mdev_aqm, lstdev->matrix.aqm, AP_DOMAINS))
 			continue;
 
+		vfio_ap_mdev_log_sharing_err(dev_name(mdev_dev(lstdev->mdev)),
+					     apm, aqm);
+
 		return -EADDRINUSE;
 	}
 
@@ -642,6 +661,7 @@ static ssize_t assign_adapter_store(struct device *dev,
 {
 	int ret;
 	unsigned long apid;
+	DECLARE_BITMAP(apm, AP_DEVICES);
 	struct mdev_device *mdev = mdev_from_dev(dev);
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
@@ -667,18 +687,18 @@ static ssize_t assign_adapter_store(struct device *dev,
 	if (ret)
 		goto done;
 
-	set_bit_inv(apid, matrix_mdev->matrix.apm);
+	memset(apm, 0, sizeof(apm));
+	set_bit_inv(apid, apm);
 
-	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
+	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev, apm,
+					     matrix_mdev->matrix.aqm);
 	if (ret)
-		goto share_err;
+		goto done;
 
+	set_bit_inv(apid, matrix_mdev->matrix.apm);
 	vfio_ap_mdev_link_queues(matrix_mdev, LINK_APID, apid);
 	ret = count;
-	goto done;
 
-share_err:
-	clear_bit_inv(apid, matrix_mdev->matrix.apm);
 done:
 	mutex_unlock(&matrix_dev->lock);
 
@@ -790,6 +810,7 @@ static ssize_t assign_domain_store(struct device *dev,
 {
 	int ret;
 	unsigned long apqi;
+	DECLARE_BITMAP(aqm, AP_DOMAINS);
 	struct mdev_device *mdev = mdev_from_dev(dev);
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
@@ -810,18 +831,18 @@ static ssize_t assign_domain_store(struct device *dev,
 	if (ret)
 		goto done;
 
-	set_bit_inv(apqi, matrix_mdev->matrix.aqm);
+	memset(aqm, 0, sizeof(aqm));
+	set_bit_inv(apqi, aqm);
 
-	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
+	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev,
+					     matrix_mdev->matrix.apm, aqm);
 	if (ret)
-		goto share_err;
+		goto done;
 
+	set_bit_inv(apqi, matrix_mdev->matrix.aqm);
 	vfio_ap_mdev_link_queues(matrix_mdev, LINK_APQI, apqi);
 	ret = count;
-	goto done;
 
-share_err:
-	clear_bit_inv(apqi, matrix_mdev->matrix.aqm);
 done:
 	mutex_unlock(&matrix_dev->lock);
 
@@ -1397,3 +1418,14 @@ void vfio_ap_mdev_remove_queue(struct ap_queue *queue)
 	kfree(q);
 	mutex_unlock(&matrix_dev->lock);
 }
+
+bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm)
+{
+	bool in_use;
+
+	mutex_lock(&matrix_dev->lock);
+	in_use = !!vfio_ap_mdev_verify_no_sharing(NULL, apm, aqm);
+	mutex_unlock(&matrix_dev->lock);
+
+	return in_use;
+}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index a2aa05bec718..ad2d5b6a2851 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -103,4 +103,6 @@ struct vfio_ap_queue {
 int vfio_ap_mdev_probe_queue(struct ap_queue *queue);
 void vfio_ap_mdev_remove_queue(struct ap_queue *queue);
 
+bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm);
+
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.21.1