only use kvm when configured

modules/nixos/qemu.nix

@@ -16,7 +16,10 @@ in {
     libvirtd = {
       enable = true;
       qemu = {
-        package = lib.mkIf cfg.kvm pkgs.qemu_kvm;
+        package =
+          if cfg.kvm
+          then pkgs.qemu_kvm
+          else config.virtualisation.libvirtd.qemu.package;
         runAsRoot = true;
         swtpm.enable = true;
         ovmf = {