refactor: drop Stdout argument from setup_serial_device()

This is also a singleton, so passing it around makes not very much
sense. Also move the call to set_stdout_nonblocking() that was done
(almost) everywhere before calling setup_serial_device() into the
function. This call was _not_ done on the ARM restore path, but that
seems more like a bug rather than intentional, so do it now.

This helps because later this function will query the logger
configuration to determine whether serial output should go to a file
instead, in which case the call to set_stdout_nonblocking() is not
needed.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

src/vmm/src/builder.rs

@@ -159,11 +159,8 @@ fn create_vmm_and_vcpus(
 
     #[cfg(target_arch = "x86_64")]
     let pio_device_manager = {
-        // Make stdout non blocking.
-        set_stdout_nonblocking();
-
         // Serial device setup.
-        let serial_device = setup_serial_device(event_manager, io::stdout())?;
+        let serial_device = setup_serial_device(event_manager)?;
 
         // x86_64 uses the i8042 reset event as the Vmm exit event.
         let reset_evt = vcpus_exit_evt.try_clone().map_err(VmmError::EventFd)?;
@@ -553,8 +550,9 @@ pub fn build_microvm_from_snapshot(
 /// Sets up the serial device.
 pub fn setup_serial_device(
     event_manager: &mut EventManager,
-    out: std::io::Stdout,
 ) -> Result<Arc<Mutex<BusDevice>>, VmmError> {
+    set_stdout_nonblocking();
+
     let interrupt_evt = EventFdTrigger::new(EventFd::new(EFD_NONBLOCK).map_err(VmmError::EventFd)?);
     let kick_stdin_read_evt =
         EventFdTrigger::new(EventFd::new(EFD_NONBLOCK).map_err(VmmError::EventFd)?);
@@ -564,7 +562,7 @@ pub fn setup_serial_device(
             SerialEventsWrapper {
                 buffer_ready_event_fd: Some(kick_stdin_read_evt),
             },
-            SerialOut::Stdout(out),
+            SerialOut::Stdout(std::io::stdout()),
         ),
         input: Some(std::io::stdin()),
     })));
@@ -625,9 +623,7 @@ fn attach_legacy_devices_aarch64(
         .contains("console=");
 
     if cmdline_contains_console {
-        // Make stdout non-blocking.
-        set_stdout_nonblocking();
-        let serial = setup_serial_device(event_manager, std::io::stdout())?;
+        let serial = setup_serial_device(event_manager)?;
         vmm.mmio_device_manager
             .register_mmio_serial(vmm.vm.fd(), &mut vmm.resource_allocator, serial, None)
             .map_err(VmmError::RegisterMMIODevice)?;

src/vmm/src/device_manager/legacy.rs

@@ -111,7 +111,7 @@ impl PortIODeviceManager {
                 SerialEventsWrapper {
                     buffer_ready_event_fd: None,
                 },
-                SerialOut::Sink
+                SerialOut::Sink,
             ),
             input: None,
         })));
@@ -121,7 +121,7 @@ impl PortIODeviceManager {
                 SerialEventsWrapper {
                     buffer_ready_event_fd: None,
                 },
-                SerialOut::Sink
+                SerialOut::Sink,
             ),
             input: None,
         })));

src/vmm/src/device_manager/persist.rs

@@ -403,10 +403,8 @@ impl<'a> Persist<'a> for MMIODeviceManager {
         {
             for state in &state.legacy_devices {
                 if state.type_ == DeviceType::Serial {
-                    let serial = crate::builder::setup_serial_device(
-                        constructor_args.event_manager,
-                        std::io::stdout(),
-                    )?;
+                    let serial =
+                        crate::builder::setup_serial_device(constructor_args.event_manager)?;
 
                     constructor_args
                         .resource_allocator