vmm_vmmd, vmm_unix: compute device name (/dev/vmm/solo5-PID) in vmm_unix (depending on host OS); also destroy this device on shutdown (used to be done by solo5-hvt, but that now drops privileges and is no longer able to do this)

src/vmm_unix.ml

@@ -150,7 +150,18 @@ let prepare name vm =
   Bos.OS.File.write (Name.image_file name) (Cstruct.to_string image) >>= fun () ->
   Ok (List.rev taps)
 
+let vm_device vm =
+  match Lazy.force uname with
+  | x when x = "FreeBSD" -> Ok ("solo5-" ^ string_of_int vm.Unikernel.pid)
+  | _ -> Error (`Msg "don't know what you mean, sorry")
+
 let shutdown name vm =
+  (* since solo5 0.4.1, it drops privileges on FreeBSD *)
+  (* this results in solo5-hvt not being able to sysctl hw.vmm.destroy *)
+  (match Lazy.force uname, vm_device vm with
+   | x, Ok name when x = "FreeBSD" ->
+     ignore (Bos.OS.Cmd.run Bos.Cmd.(v "bhyvectl" % "--destroy" % ("--vm=" ^ name)))
+   | _ -> ()) ;
   (* same order as prepare! *)
   Bos.OS.File.delete (Name.image_file name) >>= fun () ->
   Bos.OS.File.delete (Name.fifo_file name) >>= fun () ->

src/vmm_unix.mli

@@ -24,3 +24,5 @@ val find_block_devices : unit -> ((Name.t * int) list, [> R.msg ]) result
 val dump : Cstruct.t -> (unit, [> R.msg ]) result
 
 val restore : unit -> (Cstruct.t, [> R.msg | `NoFile ]) result
+
+val vm_device : Unikernel.t -> (string, [> R.msg ]) result

src/vmm_vmmd.ml

@@ -108,11 +108,12 @@ let dump_unikernels t =
 
 let setup_stats t name vm =
   let stat_out =
-    let pid = vm.Unikernel.pid in
-    let name = "solo5-" ^ string_of_int pid
+    let name = match Vmm_unix.vm_device vm with
+      | Error _ -> ""
+      | Ok name -> name
     and ifs = Unikernel.(List.combine vm.config.network_interfaces vm.taps)
     in
-    `Stats_add (name, pid, ifs)
+    `Stats_add (name, vm.Unikernel.pid, ifs)
   in
   let header = Vmm_commands.{ version = t.wire_version ; sequence = t.stats_counter ; name } in
   let t = { t with stats_counter = Int64.succ t.stats_counter } in