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Subject: Re: [PATCH v6 2/7] s390: ap: new vfio_ap_queue structure
To:     Pierre Morel <pmorel@linux.ibm.com>, borntraeger@de.ibm.com
Cc:     alex.williamson@redhat.com, cohuck@redhat.com,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        kvm@vger.kernel.org, frankja@linux.ibm.com, pasic@linux.ibm.com,
        david@redhat.com, schwidefsky@de.ibm.com,
        heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com
References: <1553265828-27823-1-git-send-email-pmorel@linux.ibm.com>
 <1553265828-27823-3-git-send-email-pmorel@linux.ibm.com>
From:   Tony Krowiak <akrowiak@linux.ibm.com>
Date:   Tue, 26 Mar 2019 16:45:21 -0400
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On 3/22/19 10:43 AM, Pierre Morel wrote:
> The AP interruptions are assigned on a queue basis and
> the GISA structure is handled on a VM basis, so that
> we need to add a structure we can retrieve from both side

s/side/sides/

> holding the information we need to handle PQAP/AQIC interception
> and setup the GISA.

s/setup/set up/

> 
> Since we can not add more information to the ap_device
> we add a new structure vfio_ap_queue, to hold per queue
> information useful to handle interruptions and set it as
> driver's data of the standard ap_queue device.
> 
> Usually, the device and the mediated device are linked together
> but in the vfio_ap driver design we have a bunch of "sub" devices
> (the ap_queue devices) belonging to the mediated device.
> 
> Linking these structure to the mediated device it is assigned to,
> with the help of the vfio_ap_queue structure will help us to
> retrieve the AP devices associated with the mediated devices
> during the mediated device operations.
> 
> ------------    -------------
> | AP queue |--> | AP_vfio_q |<----
> ------------    ------^------    |    ---------------
>                        |          <--->| matrix_mdev |
> ------------    ------v------    |    ---------------
> | AP queue |--> | AP_vfio_q |-----
> ------------    -------------
> 
> The vfio_ap_queue device will hold the following entries:
> - apqn: AP queue number (defined here)
> - isc : Interrupt subclass (defined later)
> - nib : notification information byte (defined later)
> - list: a list_head entry allowing to link this structure to a
> 	matrix mediated device it is assigned to.
> 
> The vfio_ap_queue structure is allocated when the vfio_ap_driver
> is probed and added as driver data to the ap_queue device.
> It is free on remove.
> 
> The structure is linked to the matrix_dev host device at the
> probe of the device building some kind of free list for the
> matrix mediated devices.
> 
> When the vfio_queue is associated to a matrix mediated device,
> during assign_adapter or assign_domain,
> the vfio_ap_queue device is linked to this matrix mediated device
> and unlinked when dissociated.
> 
> Queuing the devices on a list of free devices and testing the
> matrix_mdev pointer to the associated matrix allow us to know
> if the queue is associated to the matrix device and associated
> or not to a mediated device.
> 
> All the operation on the free_list must be protected by the
> VFIO AP matrix_dev lock.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>   drivers/s390/crypto/vfio_ap_drv.c     |  31 ++-
>   drivers/s390/crypto/vfio_ap_ops.c     | 423 ++++++++++++++++++----------------
>   drivers/s390/crypto/vfio_ap_private.h |   7 +
>   3 files changed, 266 insertions(+), 195 deletions(-)
> 
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index e9824c3..df6f21a 100644
> --- a/drivers/s390/crypto/vfio_ap_drv.c
> +++ b/drivers/s390/crypto/vfio_ap_drv.c
> @@ -40,14 +40,42 @@ static struct ap_device_id ap_queue_ids[] = {
>   
>   MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
>   
> +/**
> + * vfio_ap_queue_dev_probe:
> + *
> + * Allocate a vfio_ap_queue structure and associate it
> + * with the device as driver_data.
> + */
>   static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
>   {
> +	struct vfio_ap_queue *q;
> +
> +	q = kzalloc(sizeof(*q), GFP_KERNEL);
> +	if (!q)
> +		return -ENOMEM;
> +	dev_set_drvdata(&apdev->device, q);
> +	q->apqn = to_ap_queue(&apdev->device)->qid;
> +	INIT_LIST_HEAD(&q->list);
> +	mutex_lock(&matrix_dev->lock);
> +	list_add(&q->list, &matrix_dev->free_list);
> +	mutex_unlock(&matrix_dev->lock);
>   	return 0;
>   }
>   
> +/**
> + * vfio_ap_queue_dev_remove:
> + *
> + * Free the associated vfio_ap_queue structure
> + */
>   static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
>   {
> -	/* Nothing to do yet */
> +	struct vfio_ap_queue *q;
> +
> +	q = dev_get_drvdata(&apdev->device);
> +	mutex_lock(&matrix_dev->lock);
> +	list_del(&q->list);
> +	mutex_unlock(&matrix_dev->lock);
> +	kfree(q);
>   }
>   
>   static void vfio_ap_matrix_dev_release(struct device *dev)
> @@ -107,6 +135,7 @@ static int vfio_ap_matrix_dev_create(void)
>   	matrix_dev->device.bus = &matrix_bus;
>   	matrix_dev->device.release = vfio_ap_matrix_dev_release;
>   	matrix_dev->vfio_ap_drv = &vfio_ap_drv;
> +	INIT_LIST_HEAD(&matrix_dev->free_list);
>   
>   	ret = device_register(&matrix_dev->device);
>   	if (ret)
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 900b9cf..77f7bac 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -24,6 +24,68 @@
>   #define VFIO_AP_MDEV_TYPE_HWVIRT "passthrough"
>   #define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"
>   
> +/**
> + * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list
> + * @apqn: The queue APQN
> + *
> + * Retrieve a queue with a specific APQN from the list of the
> + * devices associated with a list.
> + *
> + * Returns the pointer to the associated vfio_ap_queue
> + */
> +struct vfio_ap_queue *vfio_ap_get_queue(int apqn, struct list_head *l)
> +{
> +	struct vfio_ap_queue *q;
> +
> +	list_for_each_entry(q, l, list)
> +		if (q->apqn == apqn)
> +			return q;
> +	return NULL;
> +}
> +
> +static int vfio_ap_find_any_card(int apid)
> +{
> +	struct vfio_ap_queue *q;
> +
> +	list_for_each_entry(q, &matrix_dev->free_list, list)
> +		if (AP_QID_CARD(q->apqn) == apid)
> +			return 1;
> +	return 0;
> +}
> +
> +static int vfio_ap_find_any_domain(int apqi)
> +{
> +	struct vfio_ap_queue *q;
> +
> +	list_for_each_entry(q, &matrix_dev->free_list, list)
> +		if (AP_QID_QUEUE(q->apqn) == apqi)
> +			return 1;
> +	return 0;
> +}
> +
> +static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
> +{
> +	struct ap_queue_status status;
> +	int retry = 1;
> +
> +	do {
> +		status = ap_zapq(q->apqn);
> +		switch (status.response_code) {
> +		case AP_RESPONSE_NORMAL:
> +			return 0;
> +		case AP_RESPONSE_RESET_IN_PROGRESS:
> +		case AP_RESPONSE_BUSY:
> +			msleep(20);
> +			break;
> +		default:
> +			/* things are really broken, give up */

I'm not sure things are necessarily broken. We could end up here if
the AP is removed from the configuration via the SE or SCLP Deconfigure
Adjunct Processor command.

> +			return -EIO;
> +		}
> +	} while (retry--);
> +
> +	return -EBUSY;
> +}
> +
>   static void vfio_ap_matrix_init(struct ap_config_info *info,
>   				struct ap_matrix *matrix)
>   {
> @@ -45,6 +107,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>   		return -ENOMEM;
>   	}
>   
> +	INIT_LIST_HEAD(&matrix_mdev->qlist);
>   	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
>   	mdev_set_drvdata(mdev, matrix_mdev);
>   	mutex_lock(&matrix_dev->lock);
> @@ -113,162 +176,189 @@ static struct attribute_group *vfio_ap_mdev_type_groups[] = {
>   	NULL,
>   };
>   
> -struct vfio_ap_queue_reserved {
> -	unsigned long *apid;
> -	unsigned long *apqi;
> -	bool reserved;
> -};
> +static void vfio_ap_free_queue(int apqn, struct ap_matrix_mdev *matrix_mdev)
> +{
> +	struct vfio_ap_queue *q;
> +
> +	q = vfio_ap_get_queue(apqn, &matrix_mdev->qlist);
> +	if (!q)
> +		return;
> +	q->matrix_mdev = NULL;
> +	vfio_ap_mdev_reset_queue(q);

I'm wondering if it's necessary to reset the queue here. The only time
a queue is used is when a guest using the mdev device is started. When
that guest is terminated, the fd for the mdev device is closed and the
mdev device's release callback is invoked. The release callback resets
the queues assigned to the mdev device. Is it really necessary to
reset the queue again when it is unassigned even if there would have
been no subsequent activity?

> +	list_move(&q->list, &matrix_dev->free_list);
> +}
>   
>   /**
> - * vfio_ap_has_queue
> - *
> - * @dev: an AP queue device
> - * @data: a struct vfio_ap_queue_reserved reference
> + * vfio_ap_put_all_domains:
>    *
> - * Flags whether the AP queue device (@dev) has a queue ID containing the APQN,
> - * apid or apqi specified in @data:
> + * @matrix_mdev: the matrix mediated device for which we want to associate
> + *		 all available queues with a given apqi.
> + * @apid:	 The apid which associated with all defined APQI of the
> + *		 mediated device will define a AP queue.
>    *
> - * - If @data contains both an apid and apqi value, then @data will be flagged
> - *   as reserved if the APID and APQI fields for the AP queue device matches
> - *
> - * - If @data contains only an apid value, @data will be flagged as
> - *   reserved if the APID field in the AP queue device matches
> - *
> - * - If @data contains only an apqi value, @data will be flagged as
> - *   reserved if the APQI field in the AP queue device matches
> - *
> - * Returns 0 to indicate the input to function succeeded. Returns -EINVAL if
> - * @data does not contain either an apid or apqi.
> + * We remove the queue from the list of queues associated with the
> + * mediated device and put them back to the free list of the matrix
> + * device and clear the matrix_mdev pointer.
>    */
> -static int vfio_ap_has_queue(struct device *dev, void *data)
> +static void vfio_ap_put_all_domains(struct ap_matrix_mdev *matrix_mdev,
> +				    int apid)
>   {
> -	struct vfio_ap_queue_reserved *qres = data;
> -	struct ap_queue *ap_queue = to_ap_queue(dev);
> -	ap_qid_t qid;
> -	unsigned long id;
> +	int apqi, apqn;
>   
> -	if (qres->apid && qres->apqi) {
> -		qid = AP_MKQID(*qres->apid, *qres->apqi);
> -		if (qid == ap_queue->qid)
> -			qres->reserved = true;
> -	} else if (qres->apid && !qres->apqi) {
> -		id = AP_QID_CARD(ap_queue->qid);
> -		if (id == *qres->apid)
> -			qres->reserved = true;
> -	} else if (!qres->apid && qres->apqi) {
> -		id = AP_QID_QUEUE(ap_queue->qid);
> -		if (id == *qres->apqi)
> -			qres->reserved = true;
> -	} else {
> -		return -EINVAL;
> +	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
> +		apqn = AP_MKQID(apid, apqi);
> +		vfio_ap_free_queue(apqn, matrix_mdev);
>   	}
> -
> -	return 0;
>   }
>   
>   /**
> - * vfio_ap_verify_queue_reserved
> - *
> - * @matrix_dev: a mediated matrix device
> - * @apid: an AP adapter ID
> - * @apqi: an AP queue index
> + * vfio_ap_put_all_cards:
>    *
> - * Verifies that the AP queue with @apid/@apqi is reserved by the VFIO AP device
> - * driver according to the following rules:
> + * @matrix_mdev: the matrix mediated device for which we want to associate
> + *		 all available queues with a given apqi.
> + * @apqi:	 The apqi which associated with all defined APID of the
> + *		 mediated device will define a AP queue.
>    *
> - * - If both @apid and @apqi are not NULL, then there must be an AP queue
> - *   device bound to the vfio_ap driver with the APQN identified by @apid and
> - *   @apqi
> - *
> - * - If only @apid is not NULL, then there must be an AP queue device bound
> - *   to the vfio_ap driver with an APQN containing @apid
> - *
> - * - If only @apqi is not NULL, then there must be an AP queue device bound
> - *   to the vfio_ap driver with an APQN containing @apqi
> - *
> - * Returns 0 if the AP queue is reserved; otherwise, returns -EADDRNOTAVAIL.
> + * We remove the queue from the list of queues associated with the
> + * mediated device and put them back to the free list of the matrix
> + * device and clear the matrix_mdev pointer.
>    */
> -static int vfio_ap_verify_queue_reserved(unsigned long *apid,
> -					 unsigned long *apqi)
> +static void vfio_ap_put_all_cards(struct ap_matrix_mdev *matrix_mdev, int apqi)
>   {
> -	int ret;
> -	struct vfio_ap_queue_reserved qres;
> +	int apid, apqn;
>   
> -	qres.apid = apid;
> -	qres.apqi = apqi;
> -	qres.reserved = false;
> -
> -	ret = driver_for_each_device(&matrix_dev->vfio_ap_drv->driver, NULL,
> -				     &qres, vfio_ap_has_queue);
> -	if (ret)
> -		return ret;
> +	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
> +		apqn = AP_MKQID(apid, apqi);
> +		vfio_ap_free_queue(apqn, matrix_mdev);
> +	}
> +}
>   
> -	if (qres.reserved)
> -		return 0;
> +static void move_and_set(struct list_head *src, struct list_head *dst,
> +			 struct ap_matrix_mdev *matrix_mdev)
> +{
> +	struct vfio_ap_queue *q, *qtmp;
>   
> -	return -EADDRNOTAVAIL;
> +	list_for_each_entry_safe(q, qtmp, src, list) {
> +		list_move(&q->list, dst);
> +		q->matrix_mdev = matrix_mdev;
> +	}
>   }
>   
> -static int
> -vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev,
> -					     unsigned long apid)
> +static int vfio_ap_queue_match(struct device *dev, void *data)
>   {
> -	int ret;
> -	unsigned long apqi;
> -	unsigned long nbits = matrix_mdev->matrix.aqm_max + 1;
> +	struct ap_queue *ap;
>   
> -	if (find_first_bit_inv(matrix_mdev->matrix.aqm, nbits) >= nbits)
> -		return vfio_ap_verify_queue_reserved(&apid, NULL);
> +	ap = to_ap_queue(dev);
> +	return ap->qid == *(int *)data;
> +}
>   
> -	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, nbits) {
> -		ret = vfio_ap_verify_queue_reserved(&apid, &apqi);
> -		if (ret)
> -			return ret;
> -	}
> +static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
> +{
> +	struct device *dev;
> +	struct vfio_ap_queue *q;
> +
> +	dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
> +				 &apqn, vfio_ap_queue_match);
> +	if (!dev)
> +		return NULL;
> +	q = dev_get_drvdata(dev);
> +	put_device(dev);
> +	return q;
> +}
>   
> +/**
> + * vfio_ap_get_all_domains:
> + *
> + * @matrix_mdev: the matrix mediated device for which we want to associate
> + *		 all available queues with a given apqi.
> + * @apqi:	 The apqi which associated with all defined APID of the
> + *		 mediated device will define a AP queue.
> + *
> + * We define a local list to put all queues we find on the matrix driver
> + * device list when associating the apqi with all already defined apid for
> + * this matrix mediated device.
> + *
> + * If we can get all the devices we roll them to the mediated device list
> + * If we get errors we unroll them to the free list.
> + */
> +static int vfio_ap_get_all_domains(struct ap_matrix_mdev *matrix_mdev, int apid)
> +{
> +	int apqi, apqn;
> +	int ret = 0;
> +	struct vfio_ap_queue *q;
> +	struct list_head q_list;
> +
> +	if (!vfio_ap_find_any_card(apid))
> +		return -EADDRNOTAVAIL;
> +
> +	INIT_LIST_HEAD(&q_list);
> +
> +	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
> +		apqn = AP_MKQID(apid, apqi);
> +		q = vfio_ap_find_queue(apqn);
> +		if (!q) {
> +			ret = -EADDRNOTAVAIL;
> +			goto rewind;
> +		}
> +		if (q->matrix_mdev) {

If somebody assigns the same adapter a second time, the assignment will
fail because the matrix_mdev will already have been associated with the
queue. I don't think it is appropriate to fail the assignment if the
q->matrix_mdev is the same as the input matrix_mdev. This should be
changed to:

	if (q->matrix_mdev != matrix_mdev)

> +			ret = -EADDRINUSE;
> +			goto rewind;
> +		}
> +		list_move(&q->list, &q_list);
> +	}
> +	move_and_set(&q_list, &matrix_mdev->qlist, matrix_mdev);
>   	return 0;
> +rewind:
> +	move_and_set(&q_list, &matrix_dev->free_list, NULL);
> +	return ret;
>   }
> -
>   /**
> - * vfio_ap_mdev_verify_no_sharing
> + * vfio_ap_get_all_cards:
>    *
> - * 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
> - * mediated device. AP queue sharing is not allowed.
> + * @matrix_mdev: the matrix mediated device for which we want to associate
> + *		 all available queues with a given apqi.
> + * @apqi:	 The apqi which associated with all defined APID of the
> + *		 mediated device will define a AP queue.
>    *
> - * @matrix_mdev: the mediated matrix device
> + * We define a local list to put all queues we find on the matrix device
> + * free list when associating the apqi with all already defined apid for
> + * this matrix mediated device.
>    *
> - * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE.
> + * If we can get all the devices we roll them to the mediated device list
> + * If we get errors we unroll them to the free list.
>    */
> -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
> +static int vfio_ap_get_all_cards(struct ap_matrix_mdev *matrix_mdev, int apqi)
>   {
> -	struct ap_matrix_mdev *lstdev;
> -	DECLARE_BITMAP(apm, AP_DEVICES);
> -	DECLARE_BITMAP(aqm, AP_DOMAINS);
> -
> -	list_for_each_entry(lstdev, &matrix_dev->mdev_list, node) {
> -		if (matrix_mdev == lstdev)
> -			continue;
> -
> -		memset(apm, 0, sizeof(apm));
> -		memset(aqm, 0, sizeof(aqm));
> -
> -		/*
> -		 * 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))
> -			continue;
> -
> -		if (!bitmap_and(aqm, matrix_mdev->matrix.aqm,
> -				lstdev->matrix.aqm, AP_DOMAINS))
> -			continue;
> -
> -		return -EADDRINUSE;
> +	int apid, apqn;
> +	int ret = 0;
> +	struct vfio_ap_queue *q;
> +	struct list_head q_list;
> +	struct ap_matrix_mdev *tmp = NULL;
> +
> +	if (!vfio_ap_find_any_domain(apqi))
> +		return -EADDRNOTAVAIL;
> +
> +	INIT_LIST_HEAD(&q_list);
> +
> +	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
> +		apqn = AP_MKQID(apid, apqi);
> +		q = vfio_ap_find_queue(apqn);
> +		if (!q) {
> +			ret = -EADDRNOTAVAIL;
> +			goto rewind;
> +		}
> +		if (q->matrix_mdev) {

If somebody assigns the same domain a second time, the assignment will
fail because the matrix_mdev will already have been associated with the
queue. I don't think it is appropriate to fail the assignment if the
q->matrix_mdev is the same as the input matrix_mdev. This should be
changed to:

	if (q->matrix_mdev != matrix_mdev)

> +			ret = -EADDRINUSE;
> +			goto rewind;
> +		}
> +		list_move(&q->list, &q_list);
>   	}
> -
> +	tmp = matrix_mdev;
> +	move_and_set(&q_list, &matrix_mdev->qlist, matrix_mdev);
>   	return 0;
> +rewind:
> +	move_and_set(&q_list, &matrix_dev->free_list, NULL);
> +	return ret;
>   }
>   
>   /**
> @@ -330,21 +420,15 @@ static ssize_t assign_adapter_store(struct device *dev,
>   	 */
>   	mutex_lock(&matrix_dev->lock);
>   
> -	ret = vfio_ap_mdev_verify_queues_reserved_for_apid(matrix_mdev, apid);
> +	ret = vfio_ap_get_all_domains(matrix_mdev, apid);
>   	if (ret)
>   		goto done;
>   
>   	set_bit_inv(apid, matrix_mdev->matrix.apm);
>   
> -	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
> -	if (ret)
> -		goto share_err;
> -
>   	ret = count;
>   	goto done;
>   
> -share_err:
> -	clear_bit_inv(apid, matrix_mdev->matrix.apm);
>   done:
>   	mutex_unlock(&matrix_dev->lock);
>   
> @@ -391,32 +475,13 @@ static ssize_t unassign_adapter_store(struct device *dev,
>   
>   	mutex_lock(&matrix_dev->lock);
>   	clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
> +	vfio_ap_put_all_domains(matrix_mdev, apid);
>   	mutex_unlock(&matrix_dev->lock);
>   
>   	return count;
>   }
>   static DEVICE_ATTR_WO(unassign_adapter);
>   
> -static int
> -vfio_ap_mdev_verify_queues_reserved_for_apqi(struct ap_matrix_mdev *matrix_mdev,
> -					     unsigned long apqi)
> -{
> -	int ret;
> -	unsigned long apid;
> -	unsigned long nbits = matrix_mdev->matrix.apm_max + 1;
> -
> -	if (find_first_bit_inv(matrix_mdev->matrix.apm, nbits) >= nbits)
> -		return vfio_ap_verify_queue_reserved(NULL, &apqi);
> -
> -	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, nbits) {
> -		ret = vfio_ap_verify_queue_reserved(&apid, &apqi);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> -}
> -
>   /**
>    * assign_domain_store
>    *
> @@ -471,21 +536,15 @@ static ssize_t assign_domain_store(struct device *dev,
>   
>   	mutex_lock(&matrix_dev->lock);
>   
> -	ret = vfio_ap_mdev_verify_queues_reserved_for_apqi(matrix_mdev, apqi);
> +	ret = vfio_ap_get_all_cards(matrix_mdev, apqi);
>   	if (ret)
>   		goto done;
>   
>   	set_bit_inv(apqi, matrix_mdev->matrix.aqm);
>   
> -	ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
> -	if (ret)
> -		goto share_err;
> -
>   	ret = count;
>   	goto done;
>   
> -share_err:
> -	clear_bit_inv(apqi, matrix_mdev->matrix.aqm);
>   done:
>   	mutex_unlock(&matrix_dev->lock);
>   
> @@ -533,6 +592,7 @@ static ssize_t unassign_domain_store(struct device *dev,
>   
>   	mutex_lock(&matrix_dev->lock);
>   	clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
> +	vfio_ap_put_all_cards(matrix_mdev, apqi);
>   	mutex_unlock(&matrix_dev->lock);
>   
>   	return count;
> @@ -790,49 +850,22 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
>   	return NOTIFY_OK;
>   }
>   
> -static int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
> -				    unsigned int retry)
> -{
> -	struct ap_queue_status status;
> -
> -	do {
> -		status = ap_zapq(AP_MKQID(apid, apqi));
> -		switch (status.response_code) {
> -		case AP_RESPONSE_NORMAL:
> -			return 0;
> -		case AP_RESPONSE_RESET_IN_PROGRESS:
> -		case AP_RESPONSE_BUSY:
> -			msleep(20);
> -			break;
> -		default:
> -			/* things are really broken, give up */
> -			return -EIO;
> -		}
> -	} while (retry--);
> -
> -	return -EBUSY;
> -}
> -
>   static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
>   {
>   	int ret;
>   	int rc = 0;
> -	unsigned long apid, apqi;
>   	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
> +	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) {
> -			ret = vfio_ap_mdev_reset_queue(apid, apqi, 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;
> -		}
> +	list_for_each_entry(q, &matrix_mdev->qlist, list) {
> +		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
> +		 * the remaining queues but notice the last error code.
> +		 */
> +		if (ret)
> +			rc = ret;
>   	}
>   
>   	return rc;
> @@ -868,10 +901,10 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
>   	if (matrix_mdev->kvm)
>   		kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
>   
> +	matrix_mdev->kvm = NULL;
>   	vfio_ap_mdev_reset_queues(mdev);
>   	vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
>   				 &matrix_mdev->group_notifier);
> -	matrix_mdev->kvm = NULL;
>   	module_put(THIS_MODULE);
>   }
>   
> @@ -905,7 +938,9 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
>   		ret = vfio_ap_mdev_get_device_info(arg);
>   		break;
>   	case VFIO_DEVICE_RESET:
> +		mutex_lock(&matrix_dev->lock);
>   		ret = vfio_ap_mdev_reset_queues(mdev);
> +		mutex_unlock(&matrix_dev->lock);
>   		break;
>   	default:
>   		ret = -EOPNOTSUPP;
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index a910be1..3e6940c 100644
> --- a/drivers/s390/crypto/vfio_ap_private.h
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -40,6 +40,7 @@ struct ap_matrix_dev {
>   	atomic_t available_instances;
>   	struct ap_config_info info;
>   	struct list_head mdev_list;
> +	struct list_head free_list;
>   	struct mutex lock;
>   	struct ap_driver  *vfio_ap_drv;
>   };
> @@ -83,9 +84,15 @@ struct ap_matrix_mdev {
>   	struct notifier_block group_notifier;
>   	struct kvm *kvm;
>   	struct kvm_s390_module_hook pqap_hook;
> +	struct list_head qlist;
>   };
>   
>   extern int vfio_ap_mdev_register(void);
>   extern void vfio_ap_mdev_unregister(void);
>   
> +struct vfio_ap_queue {
> +	struct list_head list;
> +	struct ap_matrix_mdev *matrix_mdev;
> +	int	apqn;
> +};
>   #endif /* _VFIO_AP_PRIVATE_H_ */
>