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[v2,00/14] Provide core infrastructure for managing open/release

Message ID 0-v2-b6a5582525c9+ff96-vfio_reflck_jgg@nvidia.com (mailing list archive)
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Series Provide core infrastructure for managing open/release | expand


Jason Gunthorpe July 20, 2021, 5:42 p.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

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

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

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

 - 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/0-v1-eaf3ccbba33c+1add0-vfio_reflck_jgg@nvidia.com

Jason Gunthorpe (12):
  vfio/samples: Remove module get/put
  vfio/mbochs: Fix missing error unwind in mbochs_probe()
  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
  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             | 158 ++----
 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                   | 457 ++++++------------
 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                           | 151 +++++-
 include/linux/mdev.h                          |   9 +-
 include/linux/vfio.h                          |  26 +-
 samples/vfio-mdev/mbochs.c                    |  23 +-
 samples/vfio-mdev/mdpy.c                      |  40 +-
 samples/vfio-mdev/mtty.c                      |  40 +-
 18 files changed, 444 insertions(+), 626 deletions(-)