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Date:   Thu, 9 Apr 2020 17:06:02 +0200
From:   Cornelia Huck <cohuck@redhat.com>
To:     Tony Krowiak <akrowiak@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, freude@linux.ibm.com, borntraeger@de.ibm.com,
        mjrosato@linux.ibm.com, pmorel@linux.ibm.com, pasic@linux.ibm.com,
        alex.williamson@redhat.com, kwankhede@nvidia.com,
        jjherne@linux.ibm.com, fiuczy@linux.ibm.com
Subject: Re: [PATCH v7 02/15] s390/vfio-ap: manage link between queue struct
 and matrix mdev
Message-ID: <20200409170602.4440be0f.cohuck@redhat.com>
In-Reply-To: <20200407192015.19887-3-akrowiak@linux.ibm.com>
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        <20200407192015.19887-3-akrowiak@linux.ibm.com>
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On Tue,  7 Apr 2020 15:20:02 -0400
Tony Krowiak <akrowiak@linux.ibm.com> wrote:

> A vfio_ap_queue structure is created for each queue device probed. To
> ensure that the matrix mdev to which a queue's APQN is assigned is linked
> to the queue structure as long as the queue device is bound to the vfio_ap
> device driver, let's go ahead and manage these links when the queue device
> is probed and removed as well as whenever an adapter or domain is assigned
> to or unassigned from the matrix mdev.
> 
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
>  drivers/s390/crypto/vfio_ap_ops.c | 75 ++++++++++++++++++++++++++++---
>  1 file changed, 70 insertions(+), 5 deletions(-)

(...)

> @@ -536,6 +531,31 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
>  	return 0;
>  }
>  
> +/**
> + * vfio_ap_mdev_qlinks_for_apid

Hm... maybe the function name should express that there's some actual
(un)linking going on?

vfio_ap_mdev_link_by_apid?

Or make this vfio_ap_mdev_link_queues() and pass in an indicator whether
the passed value is an apid or an aqid? Both function names look so
very similar to be easily confused (at least to me).

> + *
> + * @matrix_mdev: a matrix mediated device
> + * @apqi:	 the APID of one or more APQNs assigned to @matrix_mdev
> + *
> + * Set the link to @matrix_mdev for each queue device bound to the vfio_ap
> + * device driver with an APQN assigned to @matrix_mdev with the specified @apid.
> + *
> + * Note: If @matrix_mdev is NULL, the link to @matrix_mdev will be severed.
> + */
> +static void vfio_ap_mdev_qlinks_for_apid(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,
> +			     matrix_mdev->matrix.aqm_max + 1) {
> +		q = vfio_ap_get_queue(AP_MKQID(apid, apqi));
> +		if (q)
> +			q->matrix_mdev = matrix_mdev;
> +	}
> +}
> +
>  /**
>   * assign_adapter_store
>   *

(...)

> @@ -682,6 +704,31 @@ vfio_ap_mdev_verify_queues_reserved_for_apqi(struct ap_matrix_mdev *matrix_mdev,
>  	return 0;
>  }
>  
> +/**
> + * vfio_ap_mdev_qlinks_for_apqi

See my comment above.

> + *
> + * @matrix_mdev: a matrix mediated device
> + * @apqi:	 the APQI of one or more APQNs assigned to @matrix_mdev
> + *
> + * Set the link to @matrix_mdev for each queue device bound to the vfio_ap
> + * device driver with an APQN assigned to @matrix_mdev with the specified @apqi.
> + *
> + * Note: If @matrix_mdev is NULL, the link to @matrix_mdev will be severed.
> + */
> +static void vfio_ap_mdev_qlinks_for_apqi(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,
> +			     matrix_mdev->matrix.apm_max + 1) {
> +		q = vfio_ap_get_queue(AP_MKQID(apid, apqi));
> +		if (q)
> +			q->matrix_mdev = matrix_mdev;
> +	}
> +}
> +
>  /**
>   * assign_domain_store
>   *

(...)

> @@ -1270,6 +1319,21 @@ void vfio_ap_mdev_unregister(void)
>  	mdev_unregister_device(&matrix_dev->device);
>  }
>  
> +static void vfio_ap_mdev_for_queue(struct vfio_ap_queue *q)

vfio_ap_queue_link_mdev()? It is the other direction from the linking
above.

> +{
> +	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)) {
> +			q->matrix_mdev = matrix_mdev;
> +			break;
> +		}
> +	}
> +}
> +
>  int vfio_ap_mdev_probe_queue(struct ap_queue *queue)
>  {
>  	struct vfio_ap_queue *q;
> @@ -1282,6 +1346,7 @@ int vfio_ap_mdev_probe_queue(struct ap_queue *queue)
>  	dev_set_drvdata(&queue->ap_dev.device, q);
>  	q->apqn = queue->qid;
>  	q->saved_isc = VFIO_AP_ISC_INVALID;
> +	vfio_ap_mdev_for_queue(q);
>  	hash_add(matrix_dev->qtable, &q->qnode, q->apqn);
>  	mutex_unlock(&matrix_dev->lock);
>  

In general, looks sane.