vfio: allow cpr-reboot migration if suspended

Allow cpr-reboot for vfio if the guest is in the suspended runstate.  The
guest drivers' suspend methods flush outstanding requests and re-initialize
the devices, and thus there is no device state to save and restore.  The
user is responsible for suspending the guest before initiating cpr, such as
by issuing guest-suspend-ram to the qemu guest agent.

Relax the vfio blocker so it does not apply to cpr, and add a notifier that
verifies the guest is suspended.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
4 files changed