Re: [Qemu-devel] [RFC v2 0/4] adding mdev bus and vfio support

[Jike Song]

On 09/02/2016 11:03 PM, Alex Williamson wrote:
> On Fri,  2 Sep 2016 16:16:08 +0800
> Jike Song <address@hidden> wrote:
> 
>> This patchset is based on NVidia's "Add Mediated device support" series, 
>> version 6:
>>
>>      http://www.spinics.net/lists/kvm/msg136472.html
> 
> 
> Hi Jike,
> 
> I'm thrilled by your active participation here, but I'm confused which
> versions I should be reviewing and where the primary development is
> going.  Kirti sent v7 a week ago, so I would have expected a revision
> based on that rather than a re-write based on v6 plus incorporation of a
> few of Kirti's patches directly.

Hi Alex,

[Sorry! replied this on Monday but it was silently dropped by the our firewall]



The v1 of this patchset was send as incremental ones, basing on Nvidia's v6, to
demonstrate how is it possible and beneficial to:

        1, Introduce an independent device between physical and mdev;
        2, Simplify vfio-mdev and make it the most flexible for vendor drivers;

Unfortunately neither was understood or adopted in v7:

        http://www.spinics.net/lists/kvm/msg137081.html

So here came the v2, as a standalone series, to give a whole and straight
demonstration. The reason of still basing on v6:

        - Addressed all v6 comments (except the iommu part);
        - There is no comments yet for v7 (except the sysfs ones);



> I liked the last version of these
> changes a lot, but we need to figure out how to combine development
> because we do not have infinite cycles for review available :-\  Thanks!

Fully understand.

Here is the dilemma: v6 is an obsolete version to work upon, v7 is still not
at the direction we prefer. We would be highly glad and thankful if Neo/Kirti
would adopt the code in their next version, which will certainly form a
more simple and consolidated base for future co-development; otherwise
and we could at least discuss the concerns, in case of any.


--
Thanks,
Jike

>>
>>
>> Key Changes from Nvidia v6:
>>
>>      - Introduced an independent struct device to host device, thereby
>>        formed a physical-host-mdev hierarchy, and highly reused Linux
>>        driver core support;
>>
>>      - Added online/offline to mdev_bus_type, leveraging the 'online'
>>        attr support from Linux driver core;
>>
>>      - Removed mdev_class and other unecessary stuff;
>>
>>      /*
>>       * Given the changes above, the code volume of mdev core driver
>>       * dramatically reduced by ~50%.
>>       */
>>
>>
>>      - Interfaces between vfio_mdev and vendor driver are high-level,
>>        e.g. ioctl instead of get_irq_info/set_irq_info and reset,
>>        start/stop became mdev oriented, etc.;
>>
>>      /*
>>       * Given the changes above, the code volume of mdev core driver
>>       * dramatically reduced by ~64%.
>>       */
>>
>>
>> Test
>>
>>      - Tested with KVMGT
>>
>> TODO
>>
>>      - Re-implement the attribute group of host device as long as the
>>        sysfs hierarchy in discussion gets finalized;
>>
>>      - Move common routines from current vfio-pci into a higher location,
>>        export them for various VFIO bus drivers and/or mdev vendor drivers;
>>
>>      - Add implementation examples for vendor drivers to Documentation;
>>
>>      - Refine IOMMU changes
>>
>>
>>
>> Jike Song (2):
>>   Mediated device Core driver
>>   vfio: VFIO bus driver for MDEV devices
>>
>> Kirti Wankhede (2):
>>   vfio iommu: Add support for mediated devices
>>   docs: Add Documentation for Mediated devices
>>
>>  Documentation/vfio-mediated-device.txt | 203 ++++++++++++++
>>  drivers/vfio/Kconfig                   |   1 +
>>  drivers/vfio/Makefile                  |   1 +
>>  drivers/vfio/mdev/Kconfig              |  18 ++
>>  drivers/vfio/mdev/Makefile             |   5 +
>>  drivers/vfio/mdev/mdev_core.c          | 250 +++++++++++++++++
>>  drivers/vfio/mdev/mdev_driver.c        | 155 ++++++++++
>>  drivers/vfio/mdev/mdev_private.h       |  29 ++
>>  drivers/vfio/mdev/mdev_sysfs.c         | 155 ++++++++++
>>  drivers/vfio/mdev/vfio_mdev.c          | 187 ++++++++++++
>>  drivers/vfio/vfio.c                    |  82 ++++++
>>  drivers/vfio/vfio_iommu_type1.c        | 499 
>> +++++++++++++++++++++++++++++----
>>  include/linux/mdev.h                   | 159 +++++++++++
>>  include/linux/vfio.h                   |  13 +-
>>  14 files changed, 1709 insertions(+), 48 deletions(-)
>>  create mode 100644 Documentation/vfio-mediated-device.txt
>>  create mode 100644 drivers/vfio/mdev/Kconfig
>>  create mode 100644 drivers/vfio/mdev/Makefile
>>  create mode 100644 drivers/vfio/mdev/mdev_core.c
>>  create mode 100644 drivers/vfio/mdev/mdev_driver.c
>>  create mode 100644 drivers/vfio/mdev/mdev_private.h
>>  create mode 100644 drivers/vfio/mdev/mdev_sysfs.c
>>  create mode 100644 drivers/vfio/mdev/vfio_mdev.c
>>  create mode 100644 include/linux/mdev.h
>>
>