runtime-rs: log out the qemu console when debug enabled

When hypervisor's debug enabled, log out the qemu's console
messages for kernel boot debugging.

Signed-off-by: Fupan Li <fupan.lfp@antgroup.com>

src/runtime-rs/crates/hypervisor/src/qemu/inner.rs

@@ -25,11 +25,14 @@ use std::cmp::Ordering;
 use std::convert::TryInto;
 use std::path::Path;
 use std::process::Stdio;
-use tokio::sync::{mpsc, Mutex};
 use tokio::{
     io::{AsyncBufReadExt, BufReader},
     process::{Child, ChildStderr, Command},
 };
+use tokio::{
+    net::UnixStream,
+    sync::{mpsc, Mutex},
+};
 
 const VSOCK_SCHEME: &str = "vsock";
 
@@ -223,6 +226,12 @@ impl QemuInner {
             }
         }
 
+        //When hypervisor debug is enabled, output the kernel boot messages for debugging.
+        if self.config.debug_info.enable_debug {
+            let stream = UnixStream::connect(console_socket_path.as_os_str()).await?;
+            tokio::spawn(log_qemu_console(stream));
+        }
+
         Ok(())
     }
 
@@ -569,6 +578,24 @@ impl QemuInner {
     }
 }
 
+async fn log_qemu_console(console: UnixStream) -> Result<()> {
+    info!(sl!(), "starting reading qemu console");
+
+    let stderr_reader = BufReader::new(console);
+    let mut stderr_lines = stderr_reader.lines();
+
+    while let Some(buffer) = stderr_lines
+        .next_line()
+        .await
+        .context("next_line() failed on qemu console")?
+    {
+        info!(sl!(), "vm console: {:?}", buffer);
+    }
+
+    info!(sl!(), "finished reading qemu console");
+    Ok(())
+}
+
 async fn log_qemu_stderr(stderr: ChildStderr, exit_notify: mpsc::Sender<()>) -> Result<()> {
     info!(sl!(), "starting reading qemu stderr");