Re: [RFC PATCH v3 0/3] vfio: platform: return device properties for a platform device

[Antonios Motakis <antonios.motakis@huawei.com>]

Hello Eric,

Myself I am not involved with anything VFIO related at the moment, so (alas) I don't have any plans to revisit this series.

If someone decides to pick it up, of course I can offer my feedback and support.

Cheers,
Antonios

On 27-Aug-15 14:52, Eric Auger wrote:
> Hi Baptiste, Antonios,
> 
> What are the plans wrt this series? I am currently integrating another
> QEMU VFIO platform devices where this series could be useful I think
> (Feb 2015). Do you intend to follow up and bring it upstream?
> 
> Alex, do you see some show-stoppers in this series or do you advise to
> simply follow-up?
> 
> Thank you in advance
> 
> Best Regards
> 
> Eric
> 
> 
> On 12/19/2014 10:20 PM, Antonios Motakis wrote:
>> This RFC's intention is to show what an interface to access device
>> properties for the VFIO platform driver can look like. These properties
>> can be from the device tree node describing the device, or ACPI properties
>> in the future.
>>
>> If a device property corresponding to a platform device bound by VFIO PLATFORM
>> or VFIO AMBA is available, this patch series will allow the user to query
>> for this information. This can be useful for userspace drivers to automatically
>> query parameters related to the device.
>>
>> Specifically for QEMU, reading the "compatible" property of the device tree
>> node could be of use to find out what device is being assigned to the guest and
>> handle appropriately a wider range of devices in the future, and to generate an
>> appropriate device tree for the guest.
>>
>> Older versions of this series where specifically targeted at device tree
>> properties. This version has been reworked on top of Rafael J. Wysocki's
>> uniform device properties API for device tree and ACPI devices. This will allow
>> us to use the API in the future with devices described via ACPI.
>>
>> This also means a kernel including the uniform device properties API is needed
>> to apply these patches, in additon to the VFIO patches, e.g. branch pm+acpi-3.19-rc1
>> from https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/
>>
>> The API to get the list of available properties and the device tree full_name
>> have been removed. These probably don't serve an useful purpose, as the user
>> of this API need to know anyway what properties are specific to the device he
>> wants to access with VFIO. If we decide to reintroduce the list of properties
>> in the future, the generic device properties API in the kernel will have to
>> be extended accordingly.
>>
>> A kernel with this series and all the dependencies applied can be pulled from
>> branch vfio-device-properties-v3 from the repository:
>> https://github.com/virtualopensystems/linux-kvm-arm.git
>>
>> Changes since v2:
>>  - Reworked on top of Rafael J. Wysocki's uniform device properties API for
>>    device tree and ACPI
>>  - Support for u64 array properties
>>  - Removed API to get list of available properties and device tree full_name
>> Changes since v1:
>>  - Updated for VFIO platform patch series v8:
>>    VFIO AMBA devices now supported in addition to VFIO PLATFORM devices
>>  - Refactored and cleaned up the code
>>
>> Antonios Motakis (3):
>>   vfio: platform: add device properties skeleton and user API
>>   vfio: platform: access device property as a list of strings
>>   vfio: platform: return device properties as arrays of unsigned
>>     integers
>>
>>  drivers/vfio/platform/Makefile                |   3 +-
>>  drivers/vfio/platform/properties.c            | 162 ++++++++++++++++++++++++++
>>  drivers/vfio/platform/vfio_platform_common.c  |  35 ++++++
>>  drivers/vfio/platform/vfio_platform_private.h |   7 ++
>>  include/uapi/linux/vfio.h                     |  26 +++++
>>  5 files changed, 232 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/vfio/platform/properties.c
>>
> 

-- 
Antonios Motakis
Virtualization Engineer
Huawei Technologies Duesseldorf GmbH
European Research Center
Riesstrasse 25, 80992 München