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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, akrowiak@linux.ibm.com,
        pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com,
        heiko.carstens@de.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:   Harald Freudenberger <freude@linux.ibm.com>
Date:   Mon, 25 Mar 2019 09:05:39 +0100
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On 22.03.19 15:43, 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
> holding the information we need to handle PQAP/AQIC interception
> and setup the GISA.
>
> 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);
I'd add a check if q != NULL here.
> +	mutex_lock(&matrix_dev->lock);
> +	list_del(&q->list);
> +	mutex_unlock(&matrix_dev->lock);
> +	kfree(q);
I would add a line:
    dev_set_drvdata(&apdev->device, NULL);
>  }
>  
>  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 */
> +			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);
> +	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) {
> +			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) {
> +			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_ */