Re: [RFC v3 00/18] vfio: Adopt iommufd

[Eric Auger]

On 2/3/23 13:57, Jason Gunthorpe wrote:
> On Tue, Jan 31, 2023 at 09:52:47PM +0100, Eric Auger wrote:
>> Given some iommufd kernel limitations, the iommufd backend is
>> not yuet fully on par with the legacy backend w.r.t. features like:
>> - p2p mappings (you will see related error traces)
>> - coherency tracking
> You said this was a qemu side limitation?
yes that's correct. This comment will be removed.
>
>> - live migration
> The vfio kernel interfaces are deprecated,  Avihai's series here adds
> live migration support:
>
> https://lore.kernel.org/qemu-devel/20230126184948.10478-1-avihaih@nvidia.com/
>
> And there will be another series for iommufd system iommu based live
> migration

OK thanks for the pointer.
>
>> - vfio pci device hot reset
> What is needed here?

we need to revisit the vfio_pci_hot_reset() implementation in hw/vfio/pci.c
It uses VFIO_DEVICE_GET_PCI_HOT_RESET_INFO and VFIO_DEVICE_PCI_HOT_RESET
uapis
which retrieves/passes the list of iommu groups involved in the reset.
The notion of group had initially disappeared from the the iommufd BE
but I am afraid that's not that simple.

Thanks

Eric
>
> Jason
>