module/bdev_virtio_scsi: use the correct num_queues value

Parameter `num_queues` for virtio_scsi PCI device means
maximum number of queues, it SHOULD include the `eventq`
and `controlq`, while for `vhost_user` RPC call, it means
the number of IO queues, so here we use it as `max_queues`
in lib/virtio and add the fixed number queues for `vhost_user`
SCSI device.

Also fix `vhost_fuzz` to get `num_queues` earlier than
negotiate the feature bits.

Change-Id: I41b3da5e4b4dc37127befd414226ea6eafcd9ad0
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/13791
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>

lib/virtio/virtio.c

@@ -161,34 +161,32 @@ virtio_free_queues(struct virtio_dev *dev)
 }
 
 static int
-virtio_alloc_queues(struct virtio_dev *dev, uint16_t request_vq_num, uint16_t fixed_vq_num)
+virtio_alloc_queues(struct virtio_dev *dev, uint16_t max_queues, uint16_t fixed_vq_num)
 {
-	uint16_t nr_vq;
 	uint16_t i;
 	int ret;
 
-	nr_vq = request_vq_num + fixed_vq_num;
-	if (nr_vq == 0) {
+	if (max_queues == 0) {
 		/* perfectly fine to have a device with no virtqueues. */
 		return 0;
 	}
 
 	assert(dev->vqs == NULL);
-	dev->vqs = calloc(1, sizeof(struct virtqueue *) * nr_vq);
+	dev->vqs = calloc(1, sizeof(struct virtqueue *) * max_queues);
 	if (!dev->vqs) {
-		SPDK_ERRLOG("failed to allocate %"PRIu16" vqs\n", nr_vq);
+		SPDK_ERRLOG("failed to allocate %"PRIu16" vqs\n", max_queues);
 		return -ENOMEM;
 	}
 
-	for (i = 0; i < nr_vq; i++) {
+	for (i = 0; i < max_queues; i++) {
 		ret = virtio_init_queue(dev, i);
 		if (ret < 0) {
 			virtio_free_queues(dev);
 			return ret;
 		}
 	}
 
-	dev->max_queues = nr_vq;
+	dev->max_queues = max_queues;
 	dev->fixed_queues_num = fixed_vq_num;
 	return 0;
 }

module/bdev/virtio/bdev_virtio_scsi.c

@@ -357,7 +357,7 @@ virtio_user_scsi_dev_create(const char *name, const char *path,
 
 	feature_bits = VIRTIO_SCSI_DEV_SUPPORTED_FEATURES;
 	feature_bits |= (1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
-	rc = virtio_scsi_dev_init(svdev, num_queues, feature_bits);
+	rc = virtio_scsi_dev_init(svdev, num_queues + SPDK_VIRTIO_SCSI_QUEUE_NUM_FIXED, feature_bits);
 	if (rc != 0) {
 		virtio_dev_destruct(vdev);
 		free(svdev);

test/app/fuzz/vhost_fuzz/vhost_fuzz.c

@@ -209,33 +209,6 @@ virtio_dev_init(struct virtio_dev *vdev, const char *socket_path, uint64_t flags
 static int
 blk_dev_init(struct virtio_dev *vdev, const char *socket_path, uint16_t max_queues)
 {
-	uint16_t host_max_queues;
-	int rc;
-
-	if (virtio_dev_has_feature(vdev, VIRTIO_BLK_F_MQ)) {
-		rc = virtio_dev_read_dev_config(vdev, offsetof(struct virtio_blk_config, num_queues),
-						&host_max_queues, sizeof(host_max_queues));
-		if (rc) {
-			fprintf(stderr, "%s: config read failed: %s\n", vdev->name, spdk_strerror(-rc));
-			return rc;
-		}
-	} else {
-		host_max_queues = 1;
-	}
-
-	if (max_queues == 0) {
-		fprintf(stderr, "%s: requested 0 request queues (%"PRIu16" available).\n",
-			vdev->name, host_max_queues);
-		return -EINVAL;
-	}
-
-	if (max_queues > host_max_queues) {
-		fprintf(stderr, "%s: requested %"PRIu16" request queues "
-			"but only %"PRIu16" available.\n",
-			vdev->name, max_queues, host_max_queues);
-		max_queues = host_max_queues;
-	}
-
 	return virtio_dev_init(vdev, socket_path, VIRTIO_BLK_DEV_SUPPORTED_FEATURES, max_queues);
 }