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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,
        Tony Krowiak <akrowiak@linux.ibm.com>
Subject: [PATCH v17 04/15] s390/vfio-ap: manage link between queue struct and matrix mdev
Date:   Thu, 21 Oct 2021 11:23:21 -0400
Message-Id: <20211021152332.70455-5-akrowiak@linux.ibm.com>
In-Reply-To: <20211021152332.70455-1-akrowiak@linux.ibm.com>
References: <20211021152332.70455-1-akrowiak@linux.ibm.com>
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Let's create links between each queue device bound to the vfio_ap device
driver and the matrix mdev to which the queue's APQN is assigned. The idea
is to facilitate efficient retrieval of the objects representing the queue
devices and matrix mdevs as well as to verify that a queue assigned to
a matrix mdev is bound to the driver.

The links will be created as follows:

 * When the queue device is probed, if its APQN is assigned to a matrix
   mdev, the structures representing the queue device and the matrix mdev
   will be linked.

 * When an adapter or domain is assigned to a matrix mdev, for each new
   APQN assigned that references a queue device bound to the vfio_ap
   device driver, the structures representing the queue device and the
   matrix mdev will be linked.

The links will be removed as follows:

 * When the queue device is removed, if its APQN is assigned to a matrix
   mdev, the link from the structure representing the matrix mdev to the
   structure representing the queue will be removed. The link from the
   queue to the matrix mdev will be maintained because if the queue device
   is being removed due to a manual sysfs unbind, it may be needed after
   the queue is reset to clean up the IRQ resources allocated to enable AP
   interrupts for the KVM guest. Since the storage for the structure
   representing the queue device is ultimately freed by the remove
   callback, keeping the reference shouldn't be a problem.

 * When an adapter or domain is unassigned from a matrix mdev, for each
   APQN unassigned that references a queue device bound to the vfio_ap
   device driver, the structures representing the queue device and the
   matrix mdev will be unlinked.

 * When an mdev is removed, the link from any queues assigned to the mdev
   to the mdev will be removed.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_ops.c     | 192 +++++++++++++++++++++-----
 drivers/s390/crypto/vfio_ap_private.h |  14 ++
 2 files changed, 169 insertions(+), 37 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index cd2fe1586327..e2be29e9d310 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -29,32 +29,27 @@ static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
 static const struct vfio_device_ops vfio_ap_matrix_dev_ops;
 
 /**
- * vfio_ap_get_queue - retrieve a queue with a specific APQN from a list
- * @matrix_mdev: the associated mediated matrix
- * @apqn: The queue APQN
+ * vfio_ap_mdev_get_queue - retrieve a queue with a specific APQN from a
+ *			    hash table of queues assigned to a matrix mdev
+ * @matrix_mdev: the matrix mdev
+ * @apqn: The APQN of a queue device
  *
- * 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.
- *
- * Return: the pointer to the associated vfio_ap_queue
+ * Return: the pointer to the vfio_ap_queue struct representing the queue or
+ *	   NULL if the queue is not assigned to @matrix_mdev
  */
-static struct vfio_ap_queue *vfio_ap_get_queue(
+static struct vfio_ap_queue *vfio_ap_mdev_get_queue(
 					struct ap_matrix_mdev *matrix_mdev,
 					int apqn)
 {
 	struct vfio_ap_queue *q;
 
-	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;
-
-	q = vfio_ap_find_queue(apqn);
-	if (q)
-		q->matrix_mdev = matrix_mdev;
+	hash_for_each_possible(matrix_mdev->qtable.queues, q, mdev_qnode,
+			       apqn) {
+		if (q && q->apqn == apqn)
+			return q;
+	}
 
-	return q;
+	return NULL;
 }
 
 /**
@@ -172,7 +167,6 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
 		  status.response_code);
 end_free:
 	vfio_ap_free_aqic_resources(q);
-	q->matrix_mdev = NULL;
 	return status;
 }
 
@@ -292,7 +286,7 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
 	if (!matrix_mdev || !matrix_mdev->kvm)
 		goto out_unlock;
 
-	q = vfio_ap_get_queue(matrix_mdev, apqn);
+	q = vfio_ap_mdev_get_queue(matrix_mdev, apqn);
 	if (!q)
 		goto out_unlock;
 
@@ -338,6 +332,8 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
 
 	matrix_mdev->mdev = mdev;
 	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
+	hash_init(matrix_mdev->qtable.queues);
+	mdev_set_drvdata(mdev, matrix_mdev);
 	mutex_lock(&matrix_dev->lock);
 	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
 	mutex_unlock(&matrix_dev->lock);
@@ -359,6 +355,55 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
 	return ret;
 }
 
+static void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev,
+				    struct vfio_ap_queue *q)
+{
+	if (q) {
+		q->matrix_mdev = matrix_mdev;
+		hash_add(matrix_mdev->qtable.queues, &q->mdev_qnode, q->apqn);
+	}
+}
+
+static void vfio_ap_mdev_link_apqn(struct ap_matrix_mdev *matrix_mdev, int apqn)
+{
+	struct vfio_ap_queue *q;
+
+	q = vfio_ap_find_queue(apqn);
+	vfio_ap_mdev_link_queue(matrix_mdev, q);
+}
+
+static void vfio_ap_unlink_queue_fr_mdev(struct vfio_ap_queue *q)
+{
+	hash_del(&q->mdev_qnode);
+}
+
+static void vfio_ap_unlink_mdev_fr_queue(struct vfio_ap_queue *q)
+{
+	q->matrix_mdev = NULL;
+}
+
+static void vfio_ap_mdev_unlink_queue(struct vfio_ap_queue *q)
+{
+	vfio_ap_unlink_queue_fr_mdev(q);
+	vfio_ap_unlink_mdev_fr_queue(q);
+}
+
+static void vfio_ap_mdev_unlink_fr_queues(struct ap_matrix_mdev *matrix_mdev)
+{
+	struct vfio_ap_queue *q;
+	unsigned long apid, apqi;
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
+		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
+				     AP_DOMAINS) {
+			q = vfio_ap_mdev_get_queue(matrix_mdev,
+						   AP_MKQID(apid, apqi));
+			if (q)
+				q->matrix_mdev = NULL;
+		}
+	}
+}
+
 static void vfio_ap_mdev_remove(struct mdev_device *mdev)
 {
 	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(&mdev->dev);
@@ -367,6 +412,7 @@ static void vfio_ap_mdev_remove(struct mdev_device *mdev)
 
 	mutex_lock(&matrix_dev->lock);
 	vfio_ap_mdev_reset_queues(matrix_mdev);
+	vfio_ap_mdev_unlink_fr_queues(matrix_mdev);
 	list_del(&matrix_mdev->node);
 	mutex_unlock(&matrix_dev->lock);
 	vfio_uninit_group_dev(&matrix_mdev->vdev);
@@ -575,6 +621,16 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
 	return 0;
 }
 
+static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev,
+				      unsigned long apid)
+{
+	unsigned long apqi;
+
+	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS)
+		vfio_ap_mdev_link_apqn(matrix_mdev,
+				       AP_MKQID(apid, apqi));
+}
+
 /**
  * assign_adapter_store - parses the APID from @buf and sets the
  * corresponding bit in the mediated matrix device's APM
@@ -645,6 +701,7 @@ static ssize_t assign_adapter_store(struct device *dev,
 	if (ret)
 		goto share_err;
 
+	vfio_ap_mdev_link_adapter(matrix_mdev, apid);
 	ret = count;
 	goto done;
 
@@ -657,6 +714,20 @@ static ssize_t assign_adapter_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(assign_adapter);
 
+static void vfio_ap_mdev_unlink_adapter(struct ap_matrix_mdev *matrix_mdev,
+					unsigned long apid)
+{
+	unsigned long apqi;
+	struct vfio_ap_queue *q;
+
+	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
+		q = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi));
+
+		if (q)
+			vfio_ap_mdev_unlink_queue(q);
+	}
+}
+
 /**
  * unassign_adapter_store - parses the APID from @buf and clears the
  * corresponding bit in the mediated matrix device's APM
@@ -698,6 +769,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
 	}
 
 	clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
+	vfio_ap_mdev_unlink_adapter(matrix_mdev, apid);
 	ret = count;
 done:
 	mutex_unlock(&matrix_dev->lock);
@@ -725,6 +797,16 @@ vfio_ap_mdev_verify_queues_reserved_for_apqi(struct ap_matrix_mdev *matrix_mdev,
 	return 0;
 }
 
+static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev,
+				      unsigned long apqi)
+{
+	unsigned long apid;
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES)
+		vfio_ap_mdev_link_apqn(matrix_mdev,
+				       AP_MKQID(apid, apqi));
+}
+
 /**
  * assign_domain_store - parses the APQI from @buf and sets the
  * corresponding bit in the mediated matrix device's AQM
@@ -790,6 +872,7 @@ static ssize_t assign_domain_store(struct device *dev,
 	if (ret)
 		goto share_err;
 
+	vfio_ap_mdev_link_domain(matrix_mdev, apqi);
 	ret = count;
 	goto done;
 
@@ -802,6 +885,19 @@ static ssize_t assign_domain_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(assign_domain);
 
+static void vfio_ap_mdev_unlink_domain(struct ap_matrix_mdev *matrix_mdev,
+				       unsigned long apqi)
+{
+	unsigned long apid;
+	struct vfio_ap_queue *q;
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
+		q = vfio_ap_mdev_get_queue(matrix_mdev, AP_MKQID(apid, apqi));
+
+		if (q)
+			vfio_ap_mdev_unlink_queue(q);
+	}
+}
 
 /**
  * unassign_domain_store - parses the APQI from @buf and clears the
@@ -844,6 +940,7 @@ static ssize_t unassign_domain_store(struct device *dev,
 	}
 
 	clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
+	vfio_ap_mdev_unlink_domain(matrix_mdev, apqi);
 	ret = count;
 
 done:
@@ -1243,25 +1340,18 @@ static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q, unsigned int retry)
 
 static int vfio_ap_mdev_reset_queues(struct ap_matrix_mdev *matrix_mdev)
 {
-	int ret;
-	int rc = 0;
-	unsigned long apid, apqi;
+	int ret, bkt, rc = 0;
 	struct vfio_ap_queue *q;
 
-	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm,
-			     matrix_mdev->matrix.apm_max + 1) {
-		for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
-				     matrix_mdev->matrix.aqm_max + 1) {
-			q = vfio_ap_find_queue(AP_MKQID(apid, apqi));
-			ret = vfio_ap_mdev_reset_queue(q, 1);
-			/*
-			 * Regardless whether a queue turns out to be busy, or
-			 * is not operational, we need to continue resetting
-			 * the remaining queues.
-			 */
-			if (ret)
-				rc = ret;
-		}
+	hash_for_each(matrix_mdev->qtable.queues, bkt, q, mdev_qnode) {
+		ret = vfio_ap_mdev_reset_queue(q, 1);
+		/*
+		 * Regardless whether a queue turns out to be busy, or
+		 * is not operational, we need to continue resetting
+		 * the remaining queues.
+		 */
+		if (ret)
+			rc = ret;
 	}
 
 	return rc;
@@ -1410,6 +1500,28 @@ void vfio_ap_mdev_unregister(void)
 	mdev_unregister_driver(&vfio_ap_matrix_driver);
 }
 
+/*
+ * vfio_ap_queue_link_mdev
+ *
+ * @q: The queue to link with the matrix mdev.
+ *
+ * Links @q with the matrix mdev to which the queue's APQN is assigned.
+ */
+static void vfio_ap_queue_link_mdev(struct vfio_ap_queue *q)
+{
+	unsigned long apid = AP_QID_CARD(q->apqn);
+	unsigned long apqi = AP_QID_QUEUE(q->apqn);
+	struct ap_matrix_mdev *matrix_mdev;
+
+	list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
+		if (test_bit_inv(apid, matrix_mdev->matrix.apm) &&
+		    test_bit_inv(apqi, matrix_mdev->matrix.aqm)) {
+			vfio_ap_mdev_link_queue(matrix_mdev, q);
+			break;
+		}
+	}
+}
+
 int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 {
 	struct vfio_ap_queue *q;
@@ -1417,9 +1529,11 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
 	q = kzalloc(sizeof(*q), GFP_KERNEL);
 	if (!q)
 		return -ENOMEM;
+
 	mutex_lock(&matrix_dev->lock);
 	q->apqn = to_ap_queue(&apdev->device)->qid;
 	q->saved_isc = VFIO_AP_ISC_INVALID;
+	vfio_ap_queue_link_mdev(q);
 	dev_set_drvdata(&apdev->device, q);
 	mutex_unlock(&matrix_dev->lock);
 
@@ -1432,6 +1546,10 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
 
 	mutex_lock(&matrix_dev->lock);
 	q = dev_get_drvdata(&apdev->device);
+
+	if (q->matrix_mdev)
+		vfio_ap_unlink_queue_fr_mdev(q);
+
 	vfio_ap_mdev_reset_queue(q, 1);
 	dev_set_drvdata(&apdev->device, NULL);
 	kfree(q);
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index e3f0d42b094c..c1f57f89973e 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -19,6 +19,7 @@
 #include <linux/mutex.h>
 #include <linux/kvm_host.h>
 #include <linux/vfio.h>
+#include <linux/hashtable.h>
 
 #include "ap_bus.h"
 
@@ -74,6 +75,15 @@ struct ap_matrix {
 	DECLARE_BITMAP(adm, 256);
 };
 
+/**
+ * struct ap_queue_table - a table of queue objects.
+ *
+ * @queues: a hashtable of queues (struct vfio_ap_queue).
+ */
+struct ap_queue_table {
+	DECLARE_HASHTABLE(queues, 8);
+};
+
 /**
  * struct ap_matrix_mdev - Contains the data associated with a matrix mediated
  *			   device.
@@ -89,6 +99,7 @@ struct ap_matrix {
  * @pqap_hook:	the function pointer to the interception handler for the
  *		PQAP(AQIC) instruction.
  * @mdev:	the mediated device
+ * @qtable:	table of queues (struct vfio_ap_queue) assigned to the mdev
  */
 struct ap_matrix_mdev {
 	struct vfio_device vdev;
@@ -98,6 +109,7 @@ struct ap_matrix_mdev {
 	struct notifier_block iommu_notifier;
 	struct kvm *kvm;
 	struct mdev_device *mdev;
+	struct ap_queue_table qtable;
 };
 
 /**
@@ -107,6 +119,7 @@ struct ap_matrix_mdev {
  * @saved_pfn: the guest PFN pinned for the guest
  * @apqn: the APQN of the AP queue device
  * @saved_isc: the guest ISC registered with the GIB interface
+ * @mdev_qnode: allows the vfio_ap_queue struct to be added to a hashtable
  */
 struct vfio_ap_queue {
 	struct ap_matrix_mdev *matrix_mdev;
@@ -114,6 +127,7 @@ struct vfio_ap_queue {
 	int	apqn;
 #define VFIO_AP_ISC_INVALID 0xff
 	unsigned char saved_isc;
+	struct hlist_node mdev_qnode;
 };
 
 int vfio_ap_mdev_register(void);
-- 
2.31.1