CP-17631: Use combine_opts to simplify vga options

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>

Author: simonjbeaumont

xc/device.ml

@@ -1523,35 +1523,33 @@ let get_state ~xs ~qemu_domid domid =
 	with _ -> None
 
 let cmdline_of_disp info =
+	let combine_opts : bytes list option list -> bytes list = fun opts ->
+		List.map (function Some x -> x | _ -> []) opts
+		|> List.filter (function [] -> false | _ -> true)
+		|> List.flatten in
 	let vga_type_opts x =
 		let open Xenops_interface.Vgpu in
 		match x with
 		| Vgpu [{implementation = Nvidia _}] -> ["-vgpu"]
 		| Vgpu [{implementation = GVT_g gvt_g}] ->
-			[
+			let base_opts = Some [
 				"-xengt";
 				"-vgt_low_gm_sz"; Int64.to_string gvt_g.low_gm_sz;
 				"-vgt_high_gm_sz"; Int64.to_string gvt_g.high_gm_sz;
 				"-vgt_fence_sz"; Int64.to_string gvt_g.fence_sz;
-			] @ (
-				match gvt_g.monitor_config_file with
-				| Some monitor_config_file ->
-					["-vgt_monitor_config_file"; monitor_config_file]
-				| None -> []
-			) @ [
-				"-priv"
 			]
+			and config_file_opt = match gvt_g.monitor_config_file with
+			| Some path -> Some ["-vgt_monitor_config_file"; path]
+			| None -> None
+			and priv_opt = Some ["-priv"] in
+			combine_opts [base_opts; config_file_opt; priv_opt]
 		| Vgpu _ -> failwith "Unsupported vGPU configuration"
 		| Std_vga -> ["-std-vga"]
 		| Cirrus -> []
 		| GVT_d -> ["-std-vga"; "-gfx_passthru"]
 	in
 	let videoram_opt = ["-videoram"; string_of_int info.video_mib] in
 	let vnc_opts_of ip_addr_opt auto port keymap =
-		let combine_opts : bytes list option list -> bytes list = fun opts ->
-			List.map (function Some x -> x | _ -> []) opts
-			|> List.filter (function [] -> false | _ -> true)
-			|> List.flatten in
 		let ip_addr = Opt.default "127.0.0.1" ip_addr_opt in
 		let port = if auto then "1" else string_of_int port in
 		let unused_opt = if auto then Some ["-vncunused"] else None in