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

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On 3/3/19 9:09 PM, Halil Pasic wrote:
On Fri, 22 Feb 2019 16:29:56 +0100
Pierre Morel <pmorel@xxxxxxxxxxxxx> 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.
[..]
+static int vfio_ap_get_all_domains(struct ap_matrix_mdev *matrix_mdev, int apid)
+{
+	int apqi, apqn;
+	int ret = 0;
+	struct vfio_ap_queue *q;
+	struct list_head q_list;
+
+	INIT_LIST_HEAD(&q_list);
+
+	for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
+		apqn = AP_MKQID(apid, apqi);
+		q = vfio_ap_get_queue(apqn, &matrix_dev->free_list);
+		if (!q) {
+			ret = -EADDRNOTAVAIL;
+			goto rewind;
+		}
+		if (q->matrix_mdev) {
+			ret = -EADDRINUSE;

You tried to get the q from matrix_dev->free_list thus modulo races
q->matrix_mdev should be 0. This change breaks the error codes in a
sense that it becomes impossible to provoke EADDRINUSE (the proper
error code for taken by another matrix_mdev).

I don't understand what you are saying here. AFIU, the idea here is to
pull the q from the free list. If there is no q for the apqn on the free
list, then that would indicate the queue has not been bound to a driver
in which case the appropriate rc is EADDRNOTAVAIL. If the queue has
been bound, then a check is done to see whether the queue has been
associated with an mdev device. If so, the rc is -EADDRINUSE, which is
also appropriate. What am I missing?


+			goto rewind;
+		}
+		list_move(&q->list, &q_list);
+	}
+	move_and_set(&q_list, &matrix_mdev->qlist, matrix_mdev);
  	return 0;
+rewind:
+	move_and_set(&q_list, &matrix_dev->free_list, NULL);
+	return ret;
  }
-
  /**
- * vfio_ap_mdev_verify_no_sharing
+ * vfio_ap_get_all_cards:
   *
- * Verifies that the APQNs derived from the cross product of the AP adapter IDs
- * and AP queue indexes comprising the AP matrix are not configured for another
- * mediated device. AP queue sharing is not allowed.
+ * @matrix_mdev: the matrix mediated device for which we want to associate
+ *		 all available queues with a given apqi.
+ * @apqi:	 The apqi which associated with all defined APID of the
+ *		 mediated device will define a AP queue.
   *
- * @matrix_mdev: the mediated matrix device
+ * We define a local list to put all queues we find on the matrix device
+ * free list when associating the apqi with all already defined apid for
+ * this matrix mediated device.
   *
- * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE.
+ * If we can get all the devices we roll them to the mediated device list
+ * If we get errors we unroll them to the free list.
   */
-static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
+static int vfio_ap_get_all_cards(struct ap_matrix_mdev *matrix_mdev, int apqi)
  {
-	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)
-			continue;
-
-		memset(apm, 0, sizeof(apm));
-		memset(aqm, 0, sizeof(aqm));
-
-		/*
-		 * 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))
-			continue;
-
-		if (!bitmap_and(aqm, matrix_mdev->matrix.aqm,
-				lstdev->matrix.aqm, AP_DOMAINS))
-			continue;
-
-		return -EADDRINUSE;
+	int apid, apqn;
+	int ret = 0;
+	struct vfio_ap_queue *q;
+	struct list_head q_list;
+	struct ap_matrix_mdev *tmp = NULL;
+
+	INIT_LIST_HEAD(&q_list);
+
+	for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
+		apqn = AP_MKQID(apid, apqi);
+		q = vfio_ap_get_queue(apqn, &matrix_dev->free_list);
+		if (!q) {
+			ret = -EADDRNOTAVAIL;
+			goto rewind;
+		}
+		if (q->matrix_mdev) {
+			ret = -EADDRINUSE;

Same here!

Regards,
Halil

+			goto rewind;
+		}
+		list_move(&q->list, &q_list);
  	}

[..]





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