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

[Kirti Wankhede <kwankhede@nvidia.com>]

Jason,

I couldn't find patch 1,2,4 and 5 of these series. Can you please keep 
kvm@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(-)
>