[PATCH v3 00/10] Move vfio_ccw to the new mdev API

[Jason Gunthorpe <jgg@nvidia.com>]

This addresses Cornelia's remark on the earlier patch that ccw has a
confusing lifecycle. While it doesn't seem like the original attempt was
functionally wrong, the result can be made better with a lot of further
work.

Reorganize the driver so that the mdev owns the private memory and
controls the lifecycle, not the css_driver. The memory associated with the
css_driver lifecycle is only the mdev_parent/mdev_type registration.

Along the way we change when the sch is quiescent or not to be linked to
the open/close_device lifetime of the vfio_device, which is sort of what
it was tring to do already, just not completely.

The troublesome racey lifecycle of the css_driver callbacks is made clear
with simple vfio_device refcounting so a callback is only delivered into a
registered vfio_device and has obvious correctness.

Move the only per-css_driver state, the "available instance" counter, into
the core code and share that logic with many of the other drivers. The
value is kept in the mdev_type memory.

This is on github: https://github.com/jgunthorpe/linux/commits/vfio_ccw

v3:
 - Rebase to Christoph's group work & rc3; use
   vfio_register_emulated_iommu_dev()
 - Remove GFP_DMA
 - Order mdev_unregister_driver() symmetrically with init
 - Rework what is considered a BROKEN event in fsm_close()
 - NOP both CCW_EVENT_OPEN/CLOSE
 - Documentation updates
 - Remane goto label to err_init vfio_ccw_mdev_probe()
 - Fix NULL pointer deref in mdev_device_create()
v2: https://lore.kernel.org/r/0-v2-7d3a384024cf+2060-ccw_mdev_jgg@nvidia.com
 - Clean up the lifecycle in ccw with 7 new patches
 - Rebase
v1: https://lore.kernel.org/all/7-v2-7667f42c9bad+935-vfio3_jgg@nvidia.com

Jason Gunthorpe (10):
  vfio/ccw: Remove unneeded GFP_DMA
  vfio/ccw: Use functions for alloc/free of the vfio_ccw_private
  vfio/ccw: Pass vfio_ccw_private not mdev_device to various functions
  vfio/ccw: Convert to use vfio_register_emulated_iommu_dev()
  vfio/ccw: Make the FSM complete and synchronize it to the mdev
  vfio/mdev: Consolidate all the device_api sysfs into the core code
  vfio/mdev: Add mdev available instance checking to the core
  vfio/ccw: Remove private->mdev
  vfio: Export vfio_device_try_get()
  vfio/ccw: Move the lifecycle of the struct vfio_ccw_private to the
    mdev

 .../driver-api/vfio-mediated-device.rst       |   8 +-
 drivers/gpu/drm/i915/gvt/kvmgt.c              |   9 +-
 drivers/s390/cio/vfio_ccw_drv.c               | 282 ++++++++----------
 drivers/s390/cio/vfio_ccw_fsm.c               | 158 +++++++---
 drivers/s390/cio/vfio_ccw_ops.c               | 240 +++++++--------
 drivers/s390/cio/vfio_ccw_private.h           |  42 ++-
 drivers/s390/crypto/vfio_ap_ops.c             |  41 +--
 drivers/s390/crypto/vfio_ap_private.h         |   2 -
 drivers/vfio/mdev/mdev_core.c                 |  13 +-
 drivers/vfio/mdev/mdev_private.h              |   2 +
 drivers/vfio/mdev/mdev_sysfs.c                |  64 +++-
 drivers/vfio/vfio.c                           |   3 +-
 include/linux/mdev.h                          |  13 +-
 include/linux/vfio.h                          |   1 +
 samples/vfio-mdev/mbochs.c                    |   9 +-
 samples/vfio-mdev/mdpy.c                      |  31 +-
 samples/vfio-mdev/mtty.c                      |  10 +-
 17 files changed, 482 insertions(+), 446 deletions(-)


base-commit: d9a0cd510c3383b61db6f70a84e0c3487f836a63
-- 
2.33.0