qemu: add xen support

pkgs/applications/virtualization/qemu/default.nix

@@ -11,6 +11,7 @@
 , vncSupport ? true, libjpeg, libpng
 , spiceSupport ? !stdenv.isDarwin, spice, spice_protocol
 , usbredirSupport ? spiceSupport, usbredir
+, xenSupport ? false, xen
 , x86Only ? false
 , nixosTestRunner ? false
 }:
@@ -25,6 +26,7 @@ in
 
 stdenv.mkDerivation rec {
   name = "qemu-"
+    + stdenv.lib.optionalString xenSupport "xen-"
     + stdenv.lib.optionalString x86Only "x86-only-"
     + stdenv.lib.optionalString nixosTestRunner "for-vm-tests-"
     + version;
@@ -47,7 +49,8 @@ stdenv.mkDerivation rec {
     ++ optionals vncSupport [ libjpeg libpng ]
     ++ optionals spiceSupport [ spice_protocol spice ]
     ++ optionals usbredirSupport [ usbredir ]
-    ++ optionals stdenv.isLinux [ alsaLib libaio libcap_ng libcap attr ];
+    ++ optionals stdenv.isLinux [ alsaLib libaio libcap_ng libcap attr ]
+    ++ optionals xenSupport [ xen ];
 
   enableParallelBuilding = true;
 
@@ -100,7 +103,8 @@ stdenv.mkDerivation rec {
     ++ optional usbredirSupport "--enable-usb-redir"
     ++ optional x86Only "--target-list=i386-softmmu,x86_64-softmmu"
     ++ optional stdenv.isDarwin "--enable-cocoa"
-    ++ optional stdenv.isLinux "--enable-linux-aio";
+    ++ optional stdenv.isLinux "--enable-linux-aio"
+    ++ optional xenSupport "--enable-xen";
 
   postFixup =
     ''

pkgs/top-level/all-packages.nix

@@ -11892,6 +11892,8 @@ with pkgs;
   watch = callPackage ../os-specific/linux/procps/watch.nix { };
 
   qemu_kvm = lowPrio (qemu.override { x86Only = true; });
+  qemu_xen = lowPrio (qemu.override { x86Only = true; xenSupport = true; });
+
   qemu_test = lowPrio (qemu.override { x86Only = true; nixosTestRunner = true; });
 
   firmwareLinuxNonfree = callPackage ../os-specific/linux/firmware/firmware-linux-nonfree { };