[V2,00/12] Introduce vfio_pci_core subsystem

Message

Yishai Hadas Aug. 18, 2021, 3:15 p.m. UTC

Prologue:

This is the second series of three to send the "mlx5_vfio_pci" driver
that has been discussed on the list for a while now. It comes on top of
the first series (i.e. Reorganize reflck to support splitting vfio_pci)
that was merged already.

 - Split vfio_pci into vfio_pci/vfio_pci_core and provide infrastructure
   for non-generic VFIO PCI drivers.
 - The new driver mlx5_vfio_pci that is a full implementation of
   suspend/resume functionality for mlx5 devices.

A preview of the third series for mlx5_vfio_pci can be seen here:
https://github.com/jgunthorpe/linux/commits/mlx5_vfio_pci
=====================

From Max Gurtovoy:
====================
This series splits the vfio_pci driver into two parts, a PCI driver and
a subsystem driver that will also be library of code. The main PCI
driver, vfio_pci.ko, will remain as before and it will use the library
module vfio_pci_core.ko to help create the vfio_device.

This series is intended to solve the issues that were raised in the
previous attempts for extending vfio-pci for device specific
functionality:

1.
https://lore.kernel.org/kvm/[e-mail]
   by Yan Zhao
2.
https://lore.kernel.org/kvm/[e-mail]
   by Longfang Liu

Also to support proposed future changes to virtio and other common
protocols to support migration:

https://lists.oasis-open.org/archives/virtio-comment/202106/msg00044.html

This subsystem framework will also ease adding new device specific
functionality to VFIO devices in the future by allowing another module
to provide the pci_driver that can setup a number of details before
registering to the VFIO subsystem, such as injecting its own operations.

This series also extends the "driver_override" mechanism. A flag is
added for PCI drivers that will declare themselves as "driver_override"
capable which sends their match table to the modules.alias file but
otherwise leaves them outside of the normal driver core auto-binding
world, like vfio_pci.

In order to get the best match for "driver_override" drivers, one can
create a userspace program to inspect the modules.alias, an example can
be found at:

https://github.com/maxgurtovoy/linux_tools/blob/main/vfio/bind_vfio_pci_driver.py

Which finds the 'best match' according to a simple algorithm: "the
driver with the fewest '*' matches wins."

For example, the vfio-pci driver will match to any pci device. So it
will have the maximal '*' matches.

In case we are looking for a match to a mlx5 based device, we'll have a
match to vfio-pci.ko and mlx5-vfio-pci.ko. We'll prefer mlx5-vfio-pci.ko
since it will have less '*' matches (probably vendor and device IDs will
match). This will work in the future for NVMe/Virtio devices that can
match according to a class code or other criteria.

v2:
Patch #6:
- Drop DRIVER_VERSION as it's useless and not required any more.

Patch #9:
- Follow Bjorn Helgaas suggestion to enable having "vfio_" prefix in
  modules.alias file without the unnecessary VFIO connection in
  pci_match_device.

- Add the sequence of commands/algorithm that is required by
  userspace to discover the matching driver to the commit message to let the
  patch documentation be self-contained.

Patch #12:
- Save compatibility with Kconfig as was asked in the mailing list.
- Drop DRIVER_VERSION as it's useless and not required any more.

Yishai

Jason Gunthorpe (2):
  vfio: Use select for eventfd
  vfio: Use kconfig if XX/endif blocks instead of repeating 'depends on'

Max Gurtovoy (9):
  vfio/pci: Rename vfio_pci.c to vfio_pci_core.c
  vfio/pci: Rename vfio_pci_private.h to vfio_pci_core.h
  vfio/pci: Rename vfio_pci_device to vfio_pci_core_device
  vfio/pci: Rename ops functions to fit core namings
  vfio/pci: Include vfio header in vfio_pci_core.h
  vfio/pci: Split the pci_driver code out of vfio_pci_core.c
  vfio/pci: Move igd initialization to vfio_pci.c
  PCI: Add 'override_only' bitmap to struct pci_device_id
  vfio/pci: Introduce vfio_pci_core.ko

Yishai Hadas (1):
  vfio/pci: Move module parameters to vfio_pci.c

 Documentation/PCI/pci.rst                     |    1 +
 drivers/pci/pci-driver.c                      |   27 +-
 drivers/vfio/Kconfig                          |   29 +-
 drivers/vfio/fsl-mc/Kconfig                   |    3 +-
 drivers/vfio/mdev/Kconfig                     |    1 -
 drivers/vfio/pci/Kconfig                      |   40 +-
 drivers/vfio/pci/Makefile                     |    8 +-
 drivers/vfio/pci/vfio_pci.c                   | 2262 +----------------
 drivers/vfio/pci/vfio_pci_config.c            |   70 +-
 drivers/vfio/pci/vfio_pci_core.c              | 2159 ++++++++++++++++
 drivers/vfio/pci/vfio_pci_igd.c               |   19 +-
 drivers/vfio/pci/vfio_pci_intrs.c             |   42 +-
 drivers/vfio/pci/vfio_pci_rdwr.c              |   18 +-
 drivers/vfio/pci/vfio_pci_zdev.c              |    4 +-
 drivers/vfio/platform/Kconfig                 |    6 +-
 drivers/vfio/platform/reset/Kconfig           |    4 +-
 include/linux/mod_devicetable.h               |    6 +
 include/linux/pci.h                           |   28 +
 .../linux/vfio_pci_core.h                     |   89 +-
 scripts/mod/devicetable-offsets.c             |    1 +
 scripts/mod/file2alias.c                      |    8 +-
 21 files changed, 2515 insertions(+), 2310 deletions(-)
 create mode 100644 drivers/vfio/pci/vfio_pci_core.c
 rename drivers/vfio/pci/vfio_pci_private.h => include/linux/vfio_pci_core.h (56%)