Re: [PATCH V2 vfio 03/11] vfio: Introduce DMA logging uAPIs

[Kirti Wankhede <kwankhede@nvidia.com>]

On 7/19/2022 7:09 AM, Tian, Kevin wrote:
>> From: Alex Williamson <alex.williamson@redhat.com>
>> Sent: Tuesday, July 19, 2022 6:30 AM
>>
>> On Thu, 14 Jul 2022 11:12:43 +0300
>> Yishai Hadas <yishaih@nvidia.com> wrote:
>>
>>> DMA logging allows a device to internally record what DMAs the device is
>>> initiating and report them back to userspace. It is part of the VFIO
>>> migration infrastructure that allows implementing dirty page tracking
>>> during the pre copy phase of live migration. Only DMA WRITEs are logged,
>>> and this API is not connected to
>> VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE.
>>>
>>> This patch introduces the DMA logging involved uAPIs.
>>>
>>> It uses the FEATURE ioctl with its GET/SET/PROBE options as of below.
>>>
>>> It exposes a PROBE option to detect if the device supports DMA logging.
>>> It exposes a SET option to start device DMA logging in given IOVAs
>>> ranges.
>>> It exposes a SET option to stop device DMA logging that was previously
>>> started.
>>> It exposes a GET option to read back and clear the device DMA log.
>>>
>>> Extra details exist as part of vfio.h per a specific option.
>>
>>
>> Kevin, Kirti, others, any comments on this uAPI proposal?  Are there
>> potentially other devices that might make use of this or is everyone
>> else waiting for IOMMU based dirty tracking?
>>
> 

I had briefly screened through it, I'm taking a closer look of it.

NVIDIA vGPU might use this API.

Thanks,
Kirti