On Mon, 21 Feb 2022 20:49:43 -0400 Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > On Mon, Feb 21, 2022 at 11:40:35AM +0000, Shameer Kolothum wrote: > > > > Hi, > > > > This series attempts to add vfio live migration support for > > HiSilicon ACC VF devices based on the new v2 migration protocol > > definition and mlx5 v8 series discussed here[0]. > > > > RFCv4 --> v5 > > - Dropped RFC tag as v2 migration APIs are more stable now. > > - Addressed review comments from Jason and Alex (Thanks!). > > > > This is sanity tested on a HiSilicon platform using the Qemu branch > > provided here[1]. > > > > Please take a look and let me know your feedback. > > > > Thanks, > > Shameer > > [0] https://lore.kernel.org/kvm/20220220095716.153757-1-yishaih@xxxxxxxxxx/ > > [1] https://github.com/jgunthorpe/qemu/commits/vfio_migration_v2 > > > > > > v3 --> RFCv4 > > -Based on migration v2 protocol and mlx5 v7 series. > > -Added RFC tag again as migration v2 protocol is still under discussion. > > -Added new patch #6 to retrieve the PF QM data. > > -PRE_COPY compatibility check is now done after the migration data > > transfer. This is not ideal and needs discussion. > > Alex, do you want to keep the PRE_COPY in just for acc for now? Or do > you think this is not a good temporary use for it? > > We have some work toward doing the compatability more generally, but I > think it will be a while before that is all settled. In the original migration protocol I recall that we discussed that using the pre-copy phase for compatibility testing, even without additional device data, as a valid use case. The migration driver of course needs to account for the fact that userspace is not required to perform a pre-copy, and therefore cannot rely on that exclusively for compatibility testing, but failing a migration earlier due to detection of an incompatibility is generally a good thing. If the ACC driver wants to re-incorporate this behavior into a non-RFC proposed series and we could align accepting them into the same kernel release, that sounds ok to me. Thanks, Alex
