[PATCH V3 00/13] Introduce vfio_pci_core subsystem

Yishai Hadas
2021-08-22T14:36:58Z

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/20200518024202.13996-1-yan.y.zhao@intel.com
by Yan Zhao
2.
https://lore.kernel.org/kvm/20210702095849.1610-1-shameerali.kolothum.thodi@huawei.com
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.

v3:
Patch #6:
- Upon error flow, print PF driver name instead of hard-coded vfio-pci.
Patch #9:
- Split into two patches and follow the notes given by Bjorn Helgaas.

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 (10):
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' field to struct pci_device_id
PCI / VFIO: Add 'override_only' support for VFIO PCI sub system
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 | 28 +-
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 | 2160 ++++++++++++++++
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 | 29 +
.../linux/vfio_pci_core.h | 89 +-
scripts/mod/devicetable-offsets.c | 1 +
scripts/mod/file2alias.c | 8 +-
21 files changed, 2518 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%)

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2.18.1