Re: [PATCH v4 3/7] s390: ap: associate a ap_vfio_queue and a matrix mdev

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On 2/27/19 4:29 AM, Pierre Morel wrote:
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@xxxxxxxxxxxxx>
---
  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.

You may want to check your email once in a while. I copied you on the
email I sent to the doc author. What you say is true and you may very
well be right, but I found the doc to be confusing in the way it was
worded. I would like to get confirmation of the need for this. Notice
that I started my sentence off with I AM NOT SURE, so I clearly wasn't
saying it is definitely not necessary.



+            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







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