On Thu, 17 Oct 2019 18:48:35 +0800 Jason Wang jasowang@redhat.com wrote:
This patch introduces a new mdev transport for virtio. This is used to use kernel virtio driver to drive the mediated device that is capable of populating virtqueue directly.
A new virtio-mdev driver will be registered to the mdev bus, when a new virtio-mdev device is probed, it will register the device with mdev based config ops. This means it is a software transport between mdev driver and mdev device. The transport was implemented through device specific ops which is a part of mdev_parent_ops now.
Signed-off-by: Jason Wang jasowang@redhat.com
drivers/virtio/Kconfig | 7 + drivers/virtio/Makefile | 1 + drivers/virtio/virtio_mdev.c | 409 +++++++++++++++++++++++++++++++++++ 3 files changed, 417 insertions(+)
(...)
+static int virtio_mdev_probe(struct device *dev) +{
- struct mdev_device *mdev = mdev_from_dev(dev);
- const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(mdev);
- struct virtio_mdev_device *vm_dev;
- int rc;
- vm_dev = devm_kzalloc(dev, sizeof(*vm_dev), GFP_KERNEL);
- if (!vm_dev)
return -ENOMEM;- vm_dev->vdev.dev.parent = dev;
- vm_dev->vdev.dev.release = virtio_mdev_release_dev;
- vm_dev->vdev.config = &virtio_mdev_config_ops;
- vm_dev->mdev = mdev;
- INIT_LIST_HEAD(&vm_dev->virtqueues);
- spin_lock_init(&vm_dev->lock);
- vm_dev->version = ops->get_mdev_features(mdev);
- if (vm_dev->version != VIRTIO_MDEV_F_VERSION_1) {
dev_err(dev, "VIRTIO_MDEV_F_VERSION_1 is mandatory\n");return -ENXIO;- }
Hm, so how is that mdev features interface supposed to work? If VIRTIO_MDEV_F_VERSION_1 is a bit, I would expect this code to test for its presence, and not for identity.
What will happen if we come up with a version 2? If this is backwards compatible, will both version 2 and version 1 be set?
- vm_dev->vdev.id.device = ops->get_device_id(mdev);
- if (vm_dev->vdev.id.device == 0)
return -ENODEV;- vm_dev->vdev.id.vendor = ops->get_vendor_id(mdev);
- rc = register_virtio_device(&vm_dev->vdev);
- if (rc)
put_device(dev);- else
dev_set_drvdata(dev, vm_dev);- return rc;
+}
(...)