On Wed, 21 Sep 2022 18:43:46 +0800 Kevin Tian <kevin.tian@xxxxxxxxx> wrote: > The idea is to let vfio core manage the vfio_device life cycle instead > of duplicating the logic cross drivers. Besides cleaner code in driver > side this also allows adding struct device to vfio_device as the first > step toward adding cdev uAPI in the future. Another benefit is that > user can now look at sysfs to decide whether a device is bound to > vfio [1], e.g.: > > /sys/devices/pci0000\:6f/0000\:6f\:01.0/vfio-dev/vfio0 > > Though most drivers can fit the new model naturally: > > - vfio_alloc_device() to allocate and initialize vfio_device > - vfio_put_device() to release vfio_device > - dev_ops->init() for driver private initialization > - dev_ops->release() for driver private cleanup > > vfio-ccw is the only exception due to a life cycle mess that its private > structure mixes both parent and mdev info hence must be alloc/freed > outside of the life cycle of vfio device. > > Per prior discussions this won't be fixed in short term by IBM folks [2]. > > Instead of waiting this series introduces a few tricks to move forward: > > - vfio_init_device() to initialize a pre-allocated device structure; > > - require *EVERY* driver to implement @release and free vfio_device > inside. Then vfio-ccw can use a completion mechanism to delay the > free to css driver; > > The second trick is not a real burden to other drivers because they > all require a @release for private cleanup anyway. Later once the ccw > mess is fixed a simple cleanup can be done by moving free from @release > to vfio core. > > Thanks > Kevin > > [1] https://listman.redhat.com/archives/libvir-list/2022-August/233482.html > [2] https://lore.kernel.org/all/0ee29bd6583f17f0ee4ec0769fa50e8ea6703623.camel@xxxxxxxxxxxxx/ > > v4: > - fix use-after-free issue in @release of mtty/mbochs and also change > mdpy/ap to free vfio-device as the last thing in @release (Alex) > - revert the rename from 'vfio' to 'vfio_group' in procfs (Alex) Applied to vfio next branch for v6.1. Thanks, Alex
