Re: [PATCH 00/12] Introduce vfio_pci_core subsystem

[Yishai Hadas <yishaih@nvidia.com>]

On 7/21/2021 7:15 PM, Yishai Hadas wrote:
> 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 sent already and pending merge [1].
>
>   - 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 all the patches can be seen here:
> https://github.com/jgunthorpe/linux/commits/mlx5_vfio_pci
>
> [1] https://lore.kernel.org/dri-devel/0-v2-b6a5582525c9+ff96-vfio_reflck_jgg@nvidia.com/T/#t
> =====================
>
>  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.
>
> 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 a PCI_ID_F_VFIO_DRIVER_OVERRIDE flag 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                      |   25 +-
>   drivers/vfio/Kconfig                          |   29 +-
>   drivers/vfio/fsl-mc/Kconfig                   |    3 +-
>   drivers/vfio/mdev/Kconfig                     |    1 -
>   drivers/vfio/pci/Kconfig                      |   39 +-
>   drivers/vfio/pci/Makefile                     |    8 +-
>   drivers/vfio/pci/vfio_pci.c                   | 2238 +----------------
>   drivers/vfio/pci/vfio_pci_config.c            |   70 +-
>   drivers/vfio/pci/vfio_pci_core.c              | 2138 ++++++++++++++++
>   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               |    7 +
>   include/linux/pci.h                           |   27 +
>   .../linux/vfio_pci_core.h                     |   89 +-
>   scripts/mod/devicetable-offsets.c             |    1 +
>   scripts/mod/file2alias.c                      |    8 +-
>   21 files changed, 2496 insertions(+), 2281 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%)
>
Hi Alex,

Based on the feedback that we got so far on this series, no functional 
changes are expected in V2.

It may include the below minor changes:

- Drop DRIVER_VERSION as it's useless and not required any more. 
(Patches #6, #12).

- Add the sequence of commands/algorithm that is required by userspace 
to discover the matching driver to the commit message of patch #9.

Do we need to wait for more feedback or that we are fine to send V2 ?

Yishai