On Tue, Jun 09, 2026 at 10:58:11AM +0300, Avihai Horon wrote:
> VFIO_REPCOPY_INFO_REINIT is checked only during precopy, before the
> switchover decision. However, the switchover decision and guest stop are
> not atomic, so a VFIO device may want to set VFIO_PRECOPY_INFO_REINIT
> and request another switchover ACK in the gap after switchover decision
> has been made but before the guest is stopped. This would be missed and
> may increase downtime.
> 
> Solve this by checking if VFIO_PRECOPY_INFO_REINIT was set during that
> gap, and request a new switchover-ack in the final save_state_pending
> call. Query precopy info after vCPUs are stopped but before
> transitioning from PRE_COPY state, when its valid to call the ioctl.
> 
> Signed-off-by: Avihai Horon <[email protected]>

This smells like a workaround of a not-proper kernel ABI.. but I assume
it's not a huge deal.

Acked-by: Peter Xu <[email protected]>

-- 
Peter Xu


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