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.
v2: - 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 (9): 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_group_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
drivers/gpu/drm/i915/gvt/kvmgt.c | 9 +- drivers/s390/cio/vfio_ccw_drv.c | 282 +++++++++++--------------- drivers/s390/cio/vfio_ccw_fsm.c | 152 ++++++++++---- 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 +- 16 files changed, 470 insertions(+), 444 deletions(-)