[PATCH 00/10] Allow mdev drivers to directly create the vfio_device

[Kirti Wankhede]

Jason,

I couldn't find patch 1,2,4 and 5 of these series. Can you please keep 
kvm at vger.kernel.org cc for all patches?

Also it will be helpful if you can add version prefix, eg. 'v3' for this 
series, in subject line.

Thanks,
Kirti

On 6/8/2021 6:25 AM, Jason Gunthorpe wrote:
> This is a "v3" of the previous posted full conversion:
>    https://lore.kernel.org/r/0-v2-7667f42c9bad+935-vfio3_jgg@nvidia.com
> 
> Without the trailing patches that are running into complications:
>   - The CCW conversion has some complicated remarks
>   - AP is waiting for some locking stuff to get worked out
>   - No feedback on GT
>   - The license change topic for removing vfio_mdev.c
> 
> Getting the baseline functionality merged will allow Intel's IDXD mdev
> driver to advance. It has already been RFC posted in the new format:
> 
> https://lore.kernel.org/kvm/162164243591.261970.3439987543338120797.stgit@djiang5-desk3.ch.intel.com/
> 
> This series includes base infrastructure and the sample conversions. The
> remaining four issues can be sorted out one by one.
> 
> The major change in v3 is to enhance the driver core support for binding
> based on the request from Christoph Hellwig and Dan Williams. Based on
> some light analysis this looks broadly useful:
> 
> https://lore.kernel.org/kvm/20210428233856.GY1370958@nvidia.com/
> 
> ====
> 
> The mdev bus's core part for managing the lifecycle of devices is mostly
> as one would expect for a driver core bus subsystem.
> 
> However instead of having a normal 'struct device_driver' and binding the
> actual mdev drivers through the standard driver core mechanisms it open
> codes this with the struct mdev_parent_ops and provides a single driver
> that shims between the VFIO core's struct vfio_device and the actual
> device driver.
> 
> Instead, allow mdev drivers implement an actual struct mdev_driver and
> directly call vfio_register_group_dev() in the probe() function for the
> mdev. Arrange to bind the created mdev_device to the mdev_driver that is
> provided by the end driver.
> 
> The actual execution flow doesn't change much, eg what was
> parent_ops->create is now device_driver->probe and it is called at almost
> the exact same time - except under the normal control of the driver core.
> 
> Ultimately converting all the drivers unlocks a fair number of additional
> VFIO simplifications and cleanups.
> 
> v3:
>   - Use device_driver_attach() from the driver core
>   - 5 new patches to make device_driver_attach() exported and usable for this
>   - Remove trailing patches for now
> v2: https://lore.kernel.org/r/0-v2-7667f42c9bad+935-vfio3_jgg@nvidia.com
>   - Keep && m in samples kconfig
>   - Restore accidently squashed removeal of vfio_mdev.c
>   - Remove indirections to call bus_register()/bus_unregister()
>   - Reflow long doc lines
> v1: https://lore.kernel.org/r/0-v1-d88406ed308e+418-vfio3_jgg@nvidia.com
> 
> Jason Gunthorpe (10):
>    driver core: Do not continue searching for drivers if deferred probe
>      is used
>    driver core: Pull required checks into driver_probe_device()
>    driver core: Flow the return code from ->probe() through to sysfs bind
>    driver core: Don't return EPROBE_DEFER to userspace during sysfs bind
>    driver core: Export device_driver_attach()
>    vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE
>    vfio/mdev: Allow the mdev_parent_ops to specify the device driver to
>      bind
>    vfio/mtty: Convert to use vfio_register_group_dev()
>    vfio/mdpy: Convert to use vfio_register_group_dev()
>    vfio/mbochs: Convert to use vfio_register_group_dev()
> 
>   Documentation/s390/vfio-ap.rst   |   1 -
>   arch/s390/Kconfig                |   2 +-
>   drivers/base/base.h              |   1 -
>   drivers/base/bus.c               |   6 +-
>   drivers/base/dd.c                | 116 ++++++++++++-------
>   drivers/gpu/drm/i915/Kconfig     |   2 +-
>   drivers/vfio/mdev/Kconfig        |   7 --
>   drivers/vfio/mdev/Makefile       |   3 +-
>   drivers/vfio/mdev/mdev_core.c    |  46 ++++++--
>   drivers/vfio/mdev/mdev_driver.c  |  10 ++
>   drivers/vfio/mdev/mdev_private.h |   2 +
>   drivers/vfio/mdev/vfio_mdev.c    |  24 +---
>   include/linux/device.h           |   2 +
>   include/linux/mdev.h             |   2 +
>   samples/Kconfig                  |   6 +-
>   samples/vfio-mdev/mbochs.c       | 163 +++++++++++++++------------
>   samples/vfio-mdev/mdpy.c         | 159 ++++++++++++++------------
>   samples/vfio-mdev/mtty.c         | 185 ++++++++++++++-----------------
>   18 files changed, 397 insertions(+), 340 deletions(-)
>