Allow modules to report data that can only be migrated after VM is stopped.
When this concept is introduced, we will need to account stopcopy size to
be part of pending_size as before.
However, when there're data only can be migrated in stopcopy phase, it
means the old "pending_size" may not always be able to reach low enough to
kickoff an slow version of query sync.
It used to be almost guaranteed to happen as all prior iterative modules
doesn't have stopcopy only data. VFIO may change that fact by having some
data that must be copied during stop phase.
So we need to make sure QEMU will kickoff a synchronized version of query
pending when all precopy data is migrated. This might be important to VFIO
to keep making progress even if the downtime cannot yet be satisfied.
So far, this patch should introduce no functional change, as no module yet
report stopcopy size.
This paves way for VFIO to properly report its pending data sizes, which
will start to include stop-only data.
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20260421202110.306051-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
ff86cf43df