Re: [RFC v3 16/18] vfio/iommufd: Implement the iommufd backend

[Eric Auger]

Hi Jason,

On 2/1/23 00:30, Jason Gunthorpe wrote:
> On Tue, Jan 31, 2023 at 09:53:03PM +0100, Eric Auger wrote:
>> From: Yi Liu <yi.l.liu@intel.com>
>>
>> Add the iommufd backend. The IOMMUFD container class is implemented
>> based on the new /dev/iommu user API. This backend obviously depends
>> on CONFIG_IOMMUFD.
>>
>> So far, the iommufd backend doesn't support live migration and
>> cache coherency yet due to missing support in the host kernel meaning
>> that only a subset of the container class callbacks is implemented.
> What is missing for cache coherency? I spent lots of time on that
> already, I thought I got everything..
I don't think there is anything missing anymore. This was about
KVM_DEV_VFIO_GROUP_ADD/DEL. With the advent of KVM_DEV_VFIO_FILE_ADD/DEL
we should be able to bridge the gap. However This RFCv3 does not support
that yet in the IOMMUFD backend. We will add this support in the next
version.

Thanks

Eric
>
> Jason
>