Re: [PATCH 6/9] vfio/migration: Implement VFIO migration protocol v2

[Joao Martins]

On 5/12/22 16:43, Avihai Horon wrote:
> Replace the current VFIO migration protocol v1 implementation with a new
> implementation corresponding to VFIO migration protocol v2.
> 
> The main changes are:
> - VFIO device state is now represented as a finite state machine instead
>   of a bitmap.
> 
> - Migration interface with kernel is now done using VFIO_DEVICE_FEATURE
>   ioctl and normal read() and write() instead of the migration region.
> 
> - As VFIO migration protocol v2 currently doesn't support the pre-copy
>   phase of migration, .save_live_pending and .save_live_iterate handlers
>   plus pre-copy relevant code are removed.
> 
> Detailed information about VFIO migration protocol v2 and difference
> compared to v1 can be found here [1].
> 
> [1]
> https://lore.kernel.org/all/20220224142024.147653-10-yishaih@nvidia.com/
> 
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
> ---
>  hw/vfio/common.c              |  21 +-
>  hw/vfio/migration.c           | 628 +++++++---------------------------
>  hw/vfio/trace-events          |   9 +-
>  include/hw/vfio/vfio-common.h |   8 +-
>  4 files changed, 153 insertions(+), 513 deletions(-)
> 
This looks like a fairly big patch, though more than 70% of it is removing
code. Perhaps you could split it into adding v2 and removing v1 afterwards, 
rather
than a single replacement patch? It's just a suggestion anyhow, to hopefully 
ease
analysis of the new additions. The removal looks to muddle a tiny bit.

I don't wanna throw you into potentially unnecessary work should maintainers 
disagree,
so here's an attempt:

        https://github.com/jpemartins/qemu/commits/for-avihai

If you apply your series on top of the same base commit (78ac2eebbab9) you 
should be able
to compare both branches.

I haven't found yet any particular flaws in your new logic (but will reply back 
if I find
any).