vmm: Make serial port controllable via command line

Add a "--serial" command line that takes as input either "off", "tty"
(default and current behaviour) and "file=/path/to/file".

When "--serial off" is used the serial device is not added to the VM
configuration at all.

Integration tests added that check for interrupts present (or not) and
that when sending to a file the file contains the expected serial
output.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

src/main.rs

@@ -88,27 +88,28 @@ fn main() {
                 .takes_value(true)
                 .min_values(1),
         )
+        .arg(
+            Arg::with_name("serial")
+                .long("serial")
+                .help("Control serial port: off|tty|file=/path/to/a/file")
+                .default_value("tty"),
+        )
         .get_matches();
 
     // These .unwrap()s cannot fail as there is a default value defined
     let cpus = cmd_arguments.value_of("cpus").unwrap();
     let memory = cmd_arguments.value_of("memory").unwrap();
+    let rng = cmd_arguments.value_of("rng").unwrap();
+    let serial = cmd_arguments.value_of("serial").unwrap();
 
     let kernel = cmd_arguments
         .value_of("kernel")
         .expect("Missing argument: kernel");
-
     let cmdline = cmd_arguments.value_of("cmdline");
 
     let disks: Option<Vec<&str>> = cmd_arguments.values_of("disk").map(|x| x.collect());
-
     let net: Option<Vec<&str>> = cmd_arguments.values_of("net").map(|x| x.collect());
-
-    // This .unwrap() cannot fail as there is a default value defined
-    let rng = cmd_arguments.value_of("rng").unwrap();
-
     let fs: Option<Vec<&str>> = cmd_arguments.values_of("fs").map(|x| x.collect());
-
     let pmem: Option<Vec<&str>> = cmd_arguments.values_of("pmem").map(|x| x.collect());
 
     let vm_config = match config::VmConfig::parse(config::VmParams {
@@ -121,6 +122,7 @@ fn main() {
         rng,
         fs,
         pmem,
+        serial,
     }) {
         Ok(config) => config,
         Err(e) => {
@@ -760,4 +762,102 @@ mod tests {
             Ok(())
         });
     }
+
+    #[test]
+    fn test_serial_disable() {
+        test_block!(tb, "", {
+            let (disks, fw_path) = prepare_files();
+            let mut child = Command::new("target/debug/cloud-hypervisor")
+                .args(&["--cpus", "1"])
+                .args(&["--memory", "size=512M"])
+                .args(&["--kernel", fw_path.as_str()])
+                .args(&["--disk", disks[0], disks[1]])
+                .args(&[
+                    "--net",
+                    "tap=,mac=12:34:56:78:90:ab,ip=192.168.2.1,mask=255.255.255.0",
+                ])
+                .args(&["--serial", "off"])
+                .spawn()
+                .unwrap();
+
+            thread::sleep(std::time::Duration::new(10, 0));
+
+            // Test that there is no ttyS0
+            aver_eq!(
+                tb,
+                ssh_command("cat /proc/interrupts | grep 'IO-APIC' | grep -c 'ttyS0'")
+                    .trim()
+                    .parse::<u32>()
+                    .unwrap(),
+                0
+            );
+
+            // Further test that we're MSI only now
+            aver_eq!(
+                tb,
+                ssh_command("cat /proc/interrupts | grep -c 'IO-APIC'")
+                    .trim()
+                    .parse::<u32>()
+                    .unwrap(),
+                0
+            );
+
+            ssh_command("sudo reboot");
+            thread::sleep(std::time::Duration::new(10, 0));
+            let _ = child.kill();
+            let _ = child.wait();
+            Ok(())
+        });
+    }
+
+    #[test]
+    fn test_serial_file() {
+        test_block!(tb, "", {
+            let serial_path = std::path::Path::new("/tmp/serial-output");
+            let (disks, fw_path) = prepare_files();
+            let mut child = Command::new("target/debug/cloud-hypervisor")
+                .args(&["--cpus", "1"])
+                .args(&["--memory", "size=512M"])
+                .args(&["--kernel", fw_path.as_str()])
+                .args(&["--disk", disks[0], disks[1]])
+                .args(&[
+                    "--net",
+                    "tap=,mac=12:34:56:78:90:ab,ip=192.168.2.1,mask=255.255.255.0",
+                ])
+                .args(&[
+                    "--serial",
+                    format!("file={}", serial_path.to_str().unwrap()).as_str(),
+                ])
+                .spawn()
+                .unwrap();
+
+            thread::sleep(std::time::Duration::new(10, 0));
+
+            // Test that there is a ttyS0
+            aver_eq!(
+                tb,
+                ssh_command("cat /proc/interrupts | grep 'IO-APIC' | grep -c 'ttyS0'")
+                    .trim()
+                    .parse::<u32>()
+                    .unwrap(),
+                1
+            );
+
+            ssh_command("sudo reboot");
+            thread::sleep(std::time::Duration::new(10, 0));
+
+            // Do this check after shutdown of the VM as an easy way to ensure
+            // all writes are flushed to disk
+            let mut f = std::fs::File::open(serial_path).unwrap();
+            let mut buf = String::new();
+            f.read_to_string(&mut buf).unwrap();
+            aver!(tb, buf.contains("cloud login:"));
+            std::fs::remove_file(serial_path).unwrap();
+
+            let _ = child.kill();
+            let _ = child.wait();
+
+            Ok(())
+        });
+    }
 }