[PATCH v2 00/15] Tidy up vfio_device life cycle

[Kevin Tian]

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 anyay. Later once the ccw
mess is fixed a simple cleanup can be done by moving free from @release
to vfio core.

v2:
 - rebase to 6.0-rc3
 - fix build warnings (lkp)
 - patch1: remove unnecessary forward reference (Jason)
 - patch10: leave device_set released by vfio core (Jason)
 - patch13: add Suggested-by
 - patch15: add ABI file sysfs-devices-vfio-dev (Alex)
 - patch15: rename 'vfio' to 'vfio_group' in procfs (Jason)
v1: https://lore.kernel.org/lkml/20220827171037.30297-1-kevin.tian@xxxxxxxxx/

--
@Alex, before knowing your merging preference this is only rebased to
6.0-rc3.

There is no conflict with:

 - Remove private items from linux/vfio_pci_core.h
 - Break up ioctl dispatch functions to one function per ioctl

But conflict exists with Jason's two series:

 - Allow MMIO regions to be exported through dma-buf
 - vfio: Split the container code into a clean layer and dedicated file

Thanks
Kevin

[1] https://listman.redhat.com/archives/libvir-list/2022-August/233482.html
[2] https://lore.kernel.org/all/0ee29bd6583f17f0ee4ec0769fa50e8ea6703623.camel@xxxxxxxxxxxxx/

Kevin Tian (6):
  vfio: Add helpers for unifying vfio_device life cycle
  drm/i915/gvt: Use the new device life cycle helpers
  vfio/platform: Use the new device life cycle helpers
  vfio/amba: Use the new device life cycle helpers
  vfio/ccw: Use the new device life cycle helpers
  vfio: Rename vfio_device_put() and vfio_device_try_get()

Yi Liu (9):
  vfio/pci: Use the new device life cycle helpers
  vfio/mlx5: Use the new device life cycle helpers
  vfio/hisi_acc: Use the new device life cycle helpers
  vfio/mdpy: Use the new device life cycle helpers
  vfio/mtty: Use the new device life cycle helpers
  vfio/mbochs: Use the new device life cycle helpers
  vfio/ap: Use the new device life cycle helpers
  vfio/fsl-mc: Use the new device life cycle helpers
  vfio: Add struct device to vfio_device

 .../ABI/testing/sysfs-devices-vfio-dev        |   8 +
 drivers/gpu/drm/i915/gvt/gvt.h                |   5 +-
 drivers/gpu/drm/i915/gvt/kvmgt.c              |  52 ++++--
 drivers/gpu/drm/i915/gvt/vgpu.c               |  33 ++--
 drivers/s390/cio/vfio_ccw_ops.c               |  52 +++++-
 drivers/s390/cio/vfio_ccw_private.h           |   3 +
 drivers/s390/crypto/vfio_ap_ops.c             |  50 +++---
 drivers/vfio/fsl-mc/vfio_fsl_mc.c             |  85 +++++----
 .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    |  80 ++++-----
 drivers/vfio/pci/mlx5/main.c                  |  49 +++--
 drivers/vfio/pci/vfio_pci.c                   |  20 +--
 drivers/vfio/pci/vfio_pci_core.c              |  23 ++-
 drivers/vfio/platform/vfio_amba.c             |  72 ++++++--
 drivers/vfio/platform/vfio_platform.c         |  66 +++++--
 drivers/vfio/platform/vfio_platform_common.c  |  71 +++-----
 drivers/vfio/platform/vfio_platform_private.h |  18 +-
 drivers/vfio/vfio_main.c                      | 167 +++++++++++++++---
 include/linux/vfio.h                          |  28 ++-
 include/linux/vfio_pci_core.h                 |   6 +-
 samples/vfio-mdev/mbochs.c                    |  73 +++++---
 samples/vfio-mdev/mdpy.c                      |  81 +++++----
 samples/vfio-mdev/mtty.c                      |  67 ++++---
 22 files changed, 729 insertions(+), 380 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-vfio-dev


base-commit: b90cb1053190353cc30f0fef0ef1f378ccc063c5
-- 
2.21.3