Re: [PATCH v1 00/18] VFIO ccw/mdev rework

Jason Gunthorpe
2022-06-02T19:29:26Z

On Thu, Jun 02, 2022 at 07:19:30PM +0200, Eric Farman wrote:
> Last autumn, Jason Gunthorpe proposed some rework of vfio-ccw [1],
> to better fit with the new mdev API (thank you!). Part of that
> series was pulled for kernel 5.16 [2], but the complexities of
> the remaining patches got them hung up behind other work.
>
> This series attempts to dust off and complete that, with the
> goal of untangling the lifecycle of a s390 subchannel when
> bound to vfio-ccw instead of the usual io_subchannel driver.
>
> Patches 1-8 are inspired by and/or split out from that series,
> in order to be consumable on their own (backports, etc.).
>
> Patches 9-12 handle the goal of making the FSM complete,
> and synchronizing the subchannel's life with that of the mdev.
> (This was the goal of patch 5 of the larger series [3].)
>
> Patches 13-14 are pulled directly from the earlier series.
> As these patches hit some other of the consumers of vfio,
> those on CC who are unfamiliar with vfio-ccw probably only
> care about these. :)
>
> Patches 15-18 links the lifecycle of the vfio_ccw_private struct
> with the mdev via a vfio reference. (Patch 17 was also pulled
> directly from the earlier series.)
>
> In the end, the subchannel probe/remove callbacks from the css
> driver simply register/unregister with vfio-mdev. The communication
> with the subchannel is delayed until the mdev routines, which
> handles all the vfio-related memory and subchannel enablement.
> There's no longer a configuration where the mdev is closed while
> the subchannel remains enabled, since that's weird.

This all looks great thanks!

I would like this to go through the VFIO tree once you repost it on v5.19-rc1

> @Jason: I carried the S-o-b/r-b tags on patches 13, 14, and 17,
> as they were cherry-picked straight from your v3.
> If you'd prefer your S-o-b on others, please let me know.

It is OK, you did a lot of work splitting things up

Thanks,
Jason