Merge pull request #420 from stlankes/nemo

add support of a configuration file

Cargo.toml

@@ -35,6 +35,7 @@ nix = { version = "0.29", features = [
     "user",
     "zerocopy",
 ] }
+toml = "0.8.20"
 oci-spec = "0.7"
 path-clean = "1.0"
 procfs = { version = "0.17", default-features = false }

src/hermit.rs

@@ -27,7 +27,7 @@ pub fn get_qemu_args(
 	netconf: &NetworkConfig,
 	app_args: &[String],
 	micro_vm: bool,
-	kvm: bool,
+	kvm_support: bool,
 	tap_fd: &Option<i32>,
 ) -> Vec<String> {
 	let mut exec_args: Vec<String> = vec![
@@ -51,14 +51,27 @@ pub fn get_qemu_args(
 	.map(|s| s.to_string())
 	.collect();
 
-	if kvm {
-		exec_args.append(
-			&mut ["--enable-kvm", "-cpu", "host"]
+	if let Some(kvm) = crate::CONFIG.kvm {
+		if kvm && kvm_support {
+			exec_args.append(
+				&mut ["--enable-kvm", "-cpu", "host"]
+					.iter()
+					.map(|s| s.to_string())
+					.collect(),
+			);
+		} else {
+			exec_args.append(
+				&mut [
+					"-cpu",
+					"qemu64,apic,fsgsbase,rdtscp,xsave,xsaveopt,fxsr,rdrand",
+				]
 				.iter()
 				.map(|s| s.to_string())
 				.collect(),
-		);
+			);
+		}
 	} else {
+		// disable kvm support, if the configuration file doesn't enable it
 		exec_args.append(
 			&mut [
 				"-cpu",

src/main.rs

@@ -36,9 +36,39 @@ use crate::spec::*;
 use crate::start::*;
 use crate::state::*;
 use clap::{crate_version, Parser, Subcommand};
-use std::fs::DirBuilder;
+use serde::Deserialize;
+use std::fs::{read_to_string, DirBuilder};
 use std::os::unix::fs::DirBuilderExt;
-use std::{env, path::PathBuf};
+use std::sync::LazyLock;
+use std::{env, path::Path, path::PathBuf};
+
+/// This is what we're going to decode into. Each field is optional, meaning
+/// that it doesn't have to be present in TOML.
+#[derive(Debug, Deserialize)]
+struct Config {
+	kvm: Option<bool>,
+}
+
+impl Config {
+	pub const fn new() -> Self {
+		Self { kvm: None }
+	}
+}
+
+static CONFIG: LazyLock<Config> =
+	LazyLock::new(
+		|| match read_to_string(Path::new("/etc/runh/config.toml")) {
+			Ok(content) => {
+				let decoded: Result<Config, toml::de::Error> = toml::from_str(&content);
+				if let Ok(config) = decoded {
+					config
+				} else {
+					Config::new()
+				}
+			}
+			Err(_) => Config::new(),
+		},
+	);
 
 fn parse_matches(cli: &Cli) {
 	let project_dir = &cli.root;