[v3,00/14] Provide core infrastructure for managing open/release

Message

Jason Gunthorpe July 29, 2021, 12:49 a.m. UTC

This is in support of Max's series to split vfio-pci. For that to work the
reflck concept embedded in vfio-pci needs to be sharable across all of the
new VFIO PCI drivers which motivated re-examining how this is
implemented.

Another significant issue is how the VFIO PCI core includes code like:

   if (pci_dev_driver(pdev) != &vfio_pci_driver)

Which is not scalable if there are going to be multiple different driver
types.

This series takes the approach of moving the "reflck" mechanism into the
core code as a "device set". Each vfio_device driver can specify how
vfio_devices are grouped into the set using a key and the set comes along
with a set-global mutex. The core code manages creating per-device set
memory and associating it with each vfio_device.

In turn this allows the core code to provide an open/close_device()
operation that is called only for the first/last FD, and is called under
the global device set lock.

Review of all the drivers show that they are either already open coding
the first/last semantic or are buggy and missing it. All drivers are
migrated/fixed to the new open/close_device ops and the unused per-FD
open()/release() ops are deleted.

The special behavior of PCI around the bus/slot "reset group" is recast in
terms of the device set which conslidates the reflck, eliminates two
touches of pci_dev_driver(), and allows the reset mechanism to share
across all VFIO PCI drivers. PCI is changed to acquire devices directly
from the device set instead of trying to work backwards from the struct
pci_device.

Overall a few minor bugs are squashed and quite a bit of code is removed
through consolidation.

v3:
 - Atomic conversion of mbochs_used_mbytes
 - Add missing vfio_uninit_group_dev in error unwind of mbochs
 - Reorganize vfio_assign_device_set()
 - Move the dev_set_list hunks to the introduction of the dev_set
 - Use if instead of ?: in fsl
 - Add a comment about the whole bus reset in vfio_pci_probe()
 - Rename vfio_pci_check_all_devices_bound() to
   vfio_pci_is_device_in_set()
 - Move logic from vfio_pci_try_bus_reset() into vfio_pci_find_reset_target()
v2: https://lore.kernel.org/r/[e-mail]
 - Reorder fsl and mbochs vfio_uninit_group_dev
 - Fix missing error unwind in mbochs
 - Return 0 from mdev open_device if there is no op
 - Fix style for else {}
 - Spelling fix for singleton
 - Acquire cur_mem under lock
 - Always use error unwind flow for vfio_pci_check_all_devices_bound()
v1: https://lore.kernel.org/r/[e-mail]

Jason Gunthorpe (12):
  vfio/samples: Remove module get/put
  vfio/mbochs: Fix missing error unwind of mbochs_used_mbytes
  vfio: Provide better generic support for open/release vfio_device_ops
  vfio/samples: Delete useless open/close
  vfio/fsl: Move to the device set infrastructure
  vfio/platform: Use open_device() instead of open coding a refcnt
    scheme
  vfio/pci: Change vfio_pci_try_bus_reset() to use the dev_set
  vfio/pci: Reorganize VFIO_DEVICE_PCI_HOT_RESET to use the device set
  vfio/mbochs: Fix close when multiple device FDs are open
  vfio/ap,ccw: Fix open/close when multiple device FDs are open
  vfio/gvt: Fix open/close when multiple device FDs are open
  vfio: Remove struct vfio_device_ops open/release

Max Gurtovoy (1):
  vfio: Introduce a vfio_uninit_group_dev() API call

Yishai Hadas (1):
  vfio/pci: Move to the device set infrastructure

 Documentation/driver-api/vfio.rst             |   4 +-
 drivers/gpu/drm/i915/gvt/kvmgt.c              |   8 +-
 drivers/s390/cio/vfio_ccw_ops.c               |   8 +-
 drivers/s390/crypto/vfio_ap_ops.c             |   8 +-
 drivers/vfio/fsl-mc/vfio_fsl_mc.c             | 159 +-----
 drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c        |   6 +-
 drivers/vfio/fsl-mc/vfio_fsl_mc_private.h     |   7 -
 drivers/vfio/mdev/vfio_mdev.c                 |  31 +-
 drivers/vfio/pci/vfio_pci.c                   | 487 +++++++-----------
 drivers/vfio/pci/vfio_pci_private.h           |   7 -
 drivers/vfio/platform/vfio_platform_common.c  |  86 ++--
 drivers/vfio/platform/vfio_platform_private.h |   1 -
 drivers/vfio/vfio.c                           | 144 +++++-
 include/linux/mdev.h                          |   9 +-
 include/linux/vfio.h                          |  26 +-
 samples/vfio-mdev/mbochs.c                    |  40 +-
 samples/vfio-mdev/mdpy.c                      |  40 +-
 samples/vfio-mdev/mtty.c                      |  40 +-
 18 files changed, 468 insertions(+), 643 deletions(-)