xapi_vm_migrate: Fix reservations not being cleared on halted VMs

Cross-pool migrations set scheduled_to_be_resident_on to the destination host,
reserving memory and vGPUs. If the VM is still halted when migration is
finished, the field is not cleared on the destination, preserving the
reservations even though they're not necessarily going to be used anytime soon.

Call force_state_reset_keep_current_operations in pool_migrate_complete on the
destination to clear the reservations among other things at the end of the
migration.

This fixes an issue when VMs migrated across pools in a halted state would take
up memory in xapi's view (but not in RRD's view), which is not intuitive and
could prevent further migrations from claiming enough free memory on the host.

Signed-off-by: Andrii Sultanov <[email protected]>

Author: last-genius

ocaml/xapi/xapi_vm_migrate.ml

@@ -489,6 +489,11 @@ let pool_migrate_complete ~__context ~vm ~host:_ =
     ~value:`restart_device_model ;
   let dbg = Context.string_of_task __context in
   let queue_name = Xapi_xenops_queue.queue_of_vm ~__context ~self:vm in
+  (* Reset the state, which will update allowed operations, clear reservations
+     for halted VMs, disconnect devices *)
+  let power_state = Db.VM.get_power_state ~__context ~self:vm in
+  Xapi_vm_lifecycle.force_state_reset_keep_current_operations ~__context
+    ~self:vm ~value:power_state ;
   if Xapi_xenops.vm_exists_in_xenopsd queue_name dbg id then (
     remove_stale_pcis ~__context ~vm ;
     Xapi_xenops.set_resident_on ~__context ~self:vm ;