xapi: use hard-pinning with best-effort as an experimental feature (CP-54234)

This allows users to enable the feature on a host by running:
    echo 1 > /etc/xenserver/features.d/hard_numa
    xe host-apply-edition edition=${CURRENT_EDITION} host-uuid=${HOST_UUID}
where CURRENT_EDITION is
    xe host-param-get param-name=edition uuid=${HOST_UUID}

set best-effort mode if it wasn't already set:
    xe host-param-set uuid=${HOST-UUID} numa-affinity-policy=best-effort

and finally restart the toolstack:
    xe-toolstack-restart

Signed-off-by: Pau Ruiz Safont <pau.ruizsafont@cloud.com>

Author: psafont

ocaml/xapi/xapi_xenops.ml

@@ -3110,6 +3110,12 @@ let resync_all_vms ~__context =
   in
   List.iter (fun vm -> refresh_vm ~__context ~self:vm) resident_vms_in_db
 
+(* experimental feature for hard-pinning vcpus *)
+let hard_numa_enabled ~__context =
+  let pool = Helpers.get_pool ~__context in
+  let restrictions = Db.Pool.get_restrictions ~__context ~self:pool in
+  List.assoc_opt "restrict_hard_numa" restrictions = Some "false"
+
 let set_numa_affinity_policy ~__context ~value =
   let dbg = Context.string_of_task __context in
   let open Xapi_xenops_queue in
@@ -3119,6 +3125,8 @@ let set_numa_affinity_policy ~__context ~value =
     match value with
     | `any ->
         Some Any
+    | `best_effort when hard_numa_enabled ~__context ->
+        Some Best_effort_hard
     | `best_effort ->
         Some Best_effort
     | `default_policy ->