Message-Id: <d46abd0d-d365-299e-0ca7-8bae13e440d6@linux.ibm.com>
Date:   Wed, 27 Feb 2019 10:29:12 +0100
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>, borntraeger@...ibm.com
Cc:     alex.williamson@...hat.com, cohuck@...hat.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, frankja@...ux.ibm.com, pasic@...ux.ibm.com,
        david@...hat.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, freude@...ux.ibm.com, mimu@...ux.ibm.com
Subject: Re: [PATCH v4 3/7] s390: ap: associate a ap_vfio_queue and a matrix
 mdev

On 26/02/2019 19:14, Tony Krowiak wrote:
> On 2/22/19 10:29 AM, Pierre Morel wrote:
>> We need to associate the ap_vfio_queue, which will hold the
>> per queue information for interrupt with a matrix mediated device
>> which hold the configuration and the way to the CRYCB.
>>
>> Let's do this when assigning a APID or a APQI to the mediated device
>> and clear the relation when unassigning.
>>
>> 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.
>>
>> When resetting an AP queue we must wait until there are no more
>> messages in the message queue before considering the queue is really
>> in a clean state.
>>
>> Let's do it and wait until the status response code indicate the
>> queue is empty after issuing a PAPQ/ZAPQ instruction.
>>
>> Being at work on the reset function, let's simplify
>> vfio_ap_mdev_reset_queue and vfio_ap_mdev_reset_queues by using the
>> vfio_ap_queue structure as parameter.
>>
>> Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
>> ---
>>   drivers/s390/crypto/vfio_ap_ops.c | 385 
>> +++++++++++++++++++-------------------
>>   1 file changed, 189 insertions(+), 196 deletions(-)

...snip...

>> +static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
>> +{
>> +    struct ap_queue_status status;
>> +    int retry = 20;
>> +
>> +    do {
>> +        status = ap_zapq(q->apqn);
>> +        switch (status.response_code) {
>> +        case AP_RESPONSE_NORMAL:
>> +            while (!status.queue_empty && retry--) {
>> +                msleep(20);
>> +                status = ap_tapq(q->apqn, NULL);
>> +            }
> 
> I am not sure the above is necessary. I have an email out to the author
> of the architecture doc to verify.

I do not know the question you asked but the documentation is very clear 
on the reset behavior: a queue is completely reseted only after the RC 
of reset/zapq is 0 and the queue_empty bit is set.

> 
>> +            if (retry <= 0)
>> +                pr_warn("%s: queue 0x%04x not empty\n",

...snip...

>> + * @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 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)
> 
> I would prefer this be named:
> 
>      vfio_ap_mdev_free_queues_with_apid()
> 
> get/put is typically used to increment/decrement reference counters.
> What you are doing in this function freeing all queues connected to 
> specified card.

OK, I can change this function name and the further one you mentioned.

> 
>>   {
>> -    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);
>>       }
> 
> Maybe you should clear the bit corresponding to apid from the APM here?

I do not think so, this is pure list handling, the APM bit is already 
cleared in the unassign_adapter_store function.

I only answered once for all comments on naming and bit mask but will 
treat them the same way.
Thanks for comments.

Regards,
Pierre



-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany

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