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Subject: Re: [PATCH v7 02/15] s390/vfio-ap: manage link between queue struct
 and matrix mdev
To:     Cornelia Huck <cohuck@redhat.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
References: <20200407192015.19887-1-akrowiak@linux.ibm.com>
 <20200407192015.19887-3-akrowiak@linux.ibm.com>
 <20200409170602.4440be0f.cohuck@redhat.com>
From:   Tony Krowiak <akrowiak@linux.ibm.com>
Message-ID: <4bebfddc-9897-b56a-59cf-84f391df57d5@linux.ibm.com>
Date:   Fri, 10 Apr 2020 11:32:20 -0400
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On 4/9/20 11:06 AM, Cornelia Huck wrote:
> 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).

I like this idea, how about vfio_ap_link_mdev_to_queues()?


>
>> + *
>> + * @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.

How about vfio_ap_link_queue_to_mdevs()?

>
>> +{
>> +	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.
>