CA-402921: Relax VIF constraint for PVS proxy

The current constraint is that the VIF used for PVS proxy must have
device number 0. It turned out that this can be relaxed. It is
sufficient to enforce that the VIF is the one with the lowest device
number for the VM.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>

ocaml/idl/datamodel_errors.ml

@@ -1818,6 +1818,11 @@ let _ =
       "The address specified is already in use by an existing PVS_server object"
     () ;
 
+  error Api_errors.pvs_vif_must_be_first_device []
+    ~doc:
+      "The VIF used by PVS proxy must be the one with the lowest device number"
+    () ;
+
   error Api_errors.usb_group_contains_vusb ["vusbs"]
     ~doc:"The USB group contains active VUSBs and cannot be deleted." () ;
   error Api_errors.usb_group_contains_pusb ["pusbs"]

ocaml/xapi-consts/api_errors.ml

@@ -1246,6 +1246,8 @@ let pvs_proxy_already_present = add_error "PVS_PROXY_ALREADY_PRESENT"
 
 let pvs_server_address_in_use = add_error "PVS_SERVER_ADDRESS_IN_USE"
 
+let pvs_vif_must_be_first_device = add_error "PVS_VIF_MUST_BE_FIRST_DEVICE"
+
 let extension_protocol_failure = add_error "EXTENSION_PROTOCOL_FAILURE"
 
 let usb_group_contains_vusb = add_error "USB_GROUP_CONTAINS_VUSB"

ocaml/xapi/xapi_pvs_proxy.ml

@@ -32,9 +32,18 @@ let create ~__context ~site ~vIF =
       ) ;
   Helpers.assert_is_valid_ref ~__context ~name:"site" ~ref:site ;
   Helpers.assert_is_valid_ref ~__context ~name:"VIF" ~ref:vIF ;
-  let device = Db.VIF.get_device ~__context ~self:vIF in
-  if device <> "0" then
-    raise Api_errors.(Server_error (invalid_device, [device])) ;
+  let device = Db.VIF.get_device ~__context ~self:vIF |> int_of_string in
+  let min_device =
+    let open Xapi_database.Db_filter_types in
+    let vm = Db.VIF.get_VM ~__context ~self:vIF in
+    Db.VIF.get_records_where ~__context
+      ~expr:(Eq (Field "VM", Literal (Ref.string_of vm)))
+    |> List.fold_left
+         (fun m (_, {API.vIF_device= d; _}) -> min m (int_of_string d))
+         device
+  in
+  if device <> min_device then
+    raise Api_errors.(Server_error (pvs_vif_must_be_first_device, [])) ;
   let pvs_proxy = Ref.make () in
   let uuid = Uuidx.(to_string (make ())) in
   Db.PVS_proxy.create ~__context ~ref:pvs_proxy ~uuid ~site ~vIF