Date:   Mon, 17 Jun 2019 12:05:48 +0200
From:   Harald Freudenberger <freude@...ux.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     borntraeger@...ibm.com, cohuck@...hat.com, frankja@...ux.ibm.com,
        david@...hat.com, mjrosato@...ux.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, pmorel@...ux.ibm.com,
        pasic@...ux.ibm.com, alex.williamson@...hat.com,
        kwankhede@...dia.com
Subject: Re: [PATCH v4 5/7] s390: vfio-ap: allow assignment of unavailable AP
 resources to mdev device

On 13.06.19 21:39, Tony Krowiak wrote:
> The AP architecture does not preclude assignment of AP resources that are
> not available. Let's go ahead and implement this facet of the AP
> architecture for linux guests.
>
> The current implementation does not allow assignment of AP adapters or
> domains to an mdev device if the APQNs resulting from the assignment
> reference AP queue devices that are not bound to the vfio_ap device
> driver. This patch allows assignment of AP resources to the mdev device as
> long as the APQNs resulting from the assignment are not reserved by the AP
> BUS for use by the zcrypt device drivers and the APQNs are not assigned to
> another mdev device.
>
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> ---
>  drivers/s390/crypto/vfio_ap_ops.c | 231 ++++++++------------------------------
>  1 file changed, 44 insertions(+), 187 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 60efd3d7896d..9db86c0db52e 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -406,122 +406,6 @@ static struct attribute_group *vfio_ap_mdev_type_groups[] = {
>  	NULL,
>  };
>  
> -struct vfio_ap_queue_reserved {
> -	unsigned long *apid;
> -	unsigned long *apqi;
> -	bool reserved;
> -};
> -
> -/**
> - * vfio_ap_has_queue
> - *
> - * @dev: an AP queue device
> - * @data: a struct vfio_ap_queue_reserved reference
> - *
> - * Flags whether the AP queue device (@dev) has a queue ID containing the APQN,
> - * apid or apqi specified in @data:
> - *
> - * - 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.
> - */
> -static int vfio_ap_has_queue(struct device *dev, void *data)
> -{
> -	struct vfio_ap_queue_reserved *qres = data;
> -	struct ap_queue *ap_queue = to_ap_queue(dev);
> -	ap_qid_t qid;
> -	unsigned long id;
> -
> -	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;
> -	}
> -
> -	return 0;
> -}
> -
> -/**
> - * vfio_ap_verify_queue_reserved
> - *
> - * @matrix_dev: a mediated matrix device
> - * @apid: an AP adapter ID
> - * @apqi: an AP queue index
> - *
> - * Verifies that the AP queue with @apid/@...i is reserved by the VFIO AP device
> - * driver according to the following rules:
> - *
> - * - 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.
> - */
> -static int vfio_ap_verify_queue_reserved(unsigned long *apid,
> -					 unsigned long *apqi)
> -{
> -	int ret;
> -	struct vfio_ap_queue_reserved qres;
> -
> -	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;
> -
> -	if (qres.reserved)
> -		return 0;
> -
> -	return -EADDRNOTAVAIL;
> -}
> -
> -static int
> -vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev,
> -					     unsigned long apid)
> -{
> -	int ret;
> -	unsigned long apqi;
> -	unsigned long nbits = matrix_mdev->matrix.aqm_max + 1;
> -
> -	if (find_first_bit_inv(matrix_mdev->matrix.aqm, nbits) >= nbits)
> -		return vfio_ap_verify_queue_reserved(&apid, NULL);
> -
> -	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, nbits) {
> -		ret = vfio_ap_verify_queue_reserved(&apid, &apqi);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> -}
> -
>  /**
>   * vfio_ap_mdev_verify_no_sharing
>   *
> @@ -529,18 +413,26 @@ vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev,
>   * and AP queue indexes comprising the AP matrix are not configured for another
>   * mediated device. AP queue sharing is not allowed.
>   *
> - * @matrix_mdev: the mediated matrix device
> + * @mdev_apm: the mask identifying the adapters assigned to mdev
> + * @mdev_apm: the mask identifying the adapters assigned to mdev
I assume you wanted to write @mdev_aqm ... queues ... at the 2nd line.
>   *
>   * 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(unsigned long *mdev_apm,
> +					  unsigned long *mdev_aqm)
>  {
>  	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)
> +		/*
> +		 * If either of the input masks belongs to the mdev to which an
> +		 * AP resource is being assigned, then we don't need to verify
> +		 * that mdev's masks.
> +		 */
> +		if ((mdev_apm == lstdev->matrix.apm) ||
> +		    (mdev_aqm == lstdev->matrix.aqm))
>  			continue;
>  
>  		memset(apm, 0, sizeof(apm));
> @@ -550,12 +442,10 @@ 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;
>  
>  		return -EADDRINUSE;
> @@ -564,6 +454,17 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
>  	return 0;
>  }
>  
> +static int vfio_ap_mdev_validate_masks(unsigned long *apm, unsigned long *aqm)
> +{
> +	int ret;
> +
> +	ret = ap_apqn_in_matrix_owned_by_def_drv(apm, aqm);
> +	if (ret)
> +		return (ret == 1) ? -EADDRNOTAVAIL : ret;
> +
> +	return vfio_ap_mdev_verify_no_sharing(apm, aqm);
> +}
> +
>  /**
>   * assign_adapter_store
>   *
> @@ -602,6 +503,7 @@ 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);
>  
> @@ -616,32 +518,19 @@ static ssize_t assign_adapter_store(struct device *dev,
>  	if (apid > matrix_mdev->matrix.apm_max)
>  		return -ENODEV;
>  
> -	/*
> -	 * Set the bit in the AP mask (APM) corresponding to the AP adapter
> -	 * number (APID). The bits in the mask, from most significant to least
> -	 * significant bit, correspond to APIDs 0-255.
> -	 */
> -	mutex_lock(&matrix_dev->lock);
> -
> -	ret = vfio_ap_mdev_verify_queues_reserved_for_apid(matrix_mdev, apid);
> -	if (ret)
> -		goto done;
> +	memset(apm, 0, ARRAY_SIZE(apm) * sizeof(*apm));
What about just memset(apm, 0, sizeof(apm));
> +	set_bit_inv(apid, apm);
>  
> +	mutex_lock(&matrix_dev->lock);
> +	ret = vfio_ap_mdev_validate_masks(apm, matrix_mdev->matrix.aqm);
> +	if (ret) {
> +		mutex_unlock(&matrix_dev->lock);
> +		return ret;
> +	}
>  	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);
>  
> -	return ret;
> +	return count;
>  }
>  static DEVICE_ATTR_WO(assign_adapter);
>  
> @@ -690,26 +579,6 @@ static ssize_t unassign_adapter_store(struct device *dev,
>  }
>  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
>   *
> @@ -748,6 +617,7 @@ static ssize_t assign_domain_store(struct device *dev,
>  {
>  	int ret;
>  	unsigned long apqi;
> +	DECLARE_BITMAP(aqm, AP_DEVICES);
AP_DEVICES -> 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;
> @@ -762,27 +632,19 @@ static ssize_t assign_domain_store(struct device *dev,
>  	if (apqi > max_apqi)
>  		return -ENODEV;
>  
> -	mutex_lock(&matrix_dev->lock);
> -
> -	ret = vfio_ap_mdev_verify_queues_reserved_for_apqi(matrix_mdev, apqi);
> -	if (ret)
> -		goto done;
> +	memset(aqm, 0, ARRAY_SIZE(aqm) * sizeof(*aqm));
memset(aqm, 0, sizeof(aqm));
> +	set_bit_inv(apqi, aqm);
>  
> +	mutex_lock(&matrix_dev->lock);
> +	ret = vfio_ap_mdev_validate_masks(matrix_mdev->matrix.apm, aqm);
> +	if (ret) {
> +		mutex_unlock(&matrix_dev->lock);
> +		return ret;
> +	}
>  	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);
>  
> -	return ret;
> +	return count;
>  }
>  static DEVICE_ATTR_WO(assign_domain);
>  
> @@ -868,11 +730,6 @@ static ssize_t assign_control_domain_store(struct device *dev,
>  	if (id > matrix_mdev->matrix.adm_max)
>  		return -ENODEV;
>  
> -	/* Set the bit in the ADM (bitmask) corresponding to the AP control
> -	 * domain number (id). The bits in the mask, from most significant to
> -	 * least significant, correspond to IDs 0 up to the one less than the
> -	 * number of control domains that can be assigned.
> -	 */
>  	mutex_lock(&matrix_dev->lock);
>  	set_bit_inv(id, matrix_mdev->matrix.adm);
>  	mutex_unlock(&matrix_dev->lock);

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