diff --git a/compos/compos_key_cmd/compos_key_cmd.cpp b/compos/compos_key_cmd/compos_key_cmd.cpp
index 04ba1d0..8b1e2b1 100644
--- a/compos/compos_key_cmd/compos_key_cmd.cpp
+++ b/compos/compos_key_cmd/compos_key_cmd.cpp
@@ -100,7 +100,7 @@
 class Callback : public BnVirtualMachineCallback {
 public:
     ::ndk::ScopedAStatus onPayloadStarted(
-            int32_t in_cid, const ::ndk::ScopedFileDescriptor& /*in_stdout*/) override {
+            int32_t in_cid, const ::ndk::ScopedFileDescriptor& /*in_stream*/) override {
         // TODO: Consider copying stdout somewhere useful?
         LOG(INFO) << "Payload started! cid = " << in_cid;
         {
diff --git a/demo/java/com/android/microdroid/demo/MainActivity.java b/demo/java/com/android/microdroid/demo/MainActivity.java
index 9374f5d..044a55d 100644
--- a/demo/java/com/android/microdroid/demo/MainActivity.java
+++ b/demo/java/com/android/microdroid/demo/MainActivity.java
@@ -24,6 +24,7 @@
 import android.system.virtualmachine.VirtualMachineConfig;
 import android.system.virtualmachine.VirtualMachineException;
 import android.system.virtualmachine.VirtualMachineManager;
+import android.util.Log;
 import android.view.View;
 import android.widget.Button;
 import android.widget.CheckBox;
@@ -50,6 +51,8 @@
  * the virtual machine to the UI.
  */
 public class MainActivity extends AppCompatActivity {
+    private static final String TAG = "MicrodroidDemo";
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -139,19 +142,24 @@
                         new VirtualMachineCallback() {
                             @Override
                             public void onPayloadStarted(
-                                    VirtualMachine vm, ParcelFileDescriptor out) {
+                                    VirtualMachine vm, ParcelFileDescriptor stream) {
+                                if (stream == null) {
+                                    mPayloadOutput.postValue("(no output available)");
+                                    return;
+                                }
                                 try {
                                     BufferedReader reader =
                                             new BufferedReader(
                                                     new InputStreamReader(
                                                             new FileInputStream(
-                                                                    out.getFileDescriptor())));
+                                                                    stream.getFileDescriptor())));
                                     String line;
                                     while ((line = reader.readLine()) != null) {
                                         mPayloadOutput.postValue(line);
                                     }
                                 } catch (IOException e) {
-                                    // Consume
+                                    Log.e(TAG, "IOException while reading payload: "
+                                            + e.getMessage());
                                 }
                             }
 
diff --git a/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java b/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java
index 07af4a1..89bb260 100644
--- a/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java
+++ b/javalib/src/android/system/virtualmachine/VirtualMachineCallback.java
@@ -17,6 +17,7 @@
 package android.system.virtualmachine;
 
 import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.os.ParcelFileDescriptor;
 
 /**
@@ -28,7 +29,7 @@
 public interface VirtualMachineCallback {
 
     /** Called when the payload starts in the VM. */
-    void onPayloadStarted(@NonNull VirtualMachine vm, @NonNull ParcelFileDescriptor stdout);
+    void onPayloadStarted(@NonNull VirtualMachine vm, @Nullable ParcelFileDescriptor stream);
 
     /** Called when the VM died. */
     void onDied(@NonNull VirtualMachine vm);
diff --git a/microdroid_manager/Android.bp b/microdroid_manager/Android.bp
index 95a7014..5fae7b1 100644
--- a/microdroid_manager/Android.bp
+++ b/microdroid_manager/Android.bp
@@ -20,6 +20,7 @@
         "liblog_rust",
         "libmicrodroid_metadata",
         "libmicrodroid_payload_config",
+        "libnix",
         "libprotobuf",
         "librustutils",
         "libserde",
diff --git a/microdroid_manager/src/main.rs b/microdroid_manager/src/main.rs
index 2fb7fdd..ee0e797 100644
--- a/microdroid_manager/src/main.rs
+++ b/microdroid_manager/src/main.rs
@@ -23,9 +23,10 @@
 use binder::{FromIBinder, Strong};
 use log::{error, info, warn};
 use microdroid_payload_config::{Task, TaskType, VmPayloadConfig};
+use nix::ioctl_read_bad;
 use rustutils::system_properties::PropertyWatcher;
-use std::fs::{self, File};
-use std::os::unix::io::{FromRawFd, IntoRawFd};
+use std::fs::{self, File, OpenOptions};
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd};
 use std::path::Path;
 use std::process::{Command, Stdio};
 use std::str;
@@ -61,6 +62,27 @@
     }
 }
 
+const IOCTL_VM_SOCKETS_GET_LOCAL_CID: usize = 0x7b9;
+ioctl_read_bad!(
+    /// Gets local cid from /dev/vsock
+    vm_sockets_get_local_cid,
+    IOCTL_VM_SOCKETS_GET_LOCAL_CID,
+    u32
+);
+
+// TODO: remove this after VS can check the peer addresses of binder clients
+fn get_local_cid() -> Result<u32> {
+    let f = OpenOptions::new()
+        .read(true)
+        .write(false)
+        .open("/dev/vsock")
+        .context("failed to open /dev/vsock")?;
+    let mut ret = 0;
+    // SAFETY: the kernel only modifies the given u32 integer.
+    unsafe { vm_sockets_get_local_cid(f.as_raw_fd(), &mut ret) }?;
+    Ok(ret)
+}
+
 fn main() -> Result<()> {
     kernlog::init()?;
     info!("started.");
@@ -72,10 +94,7 @@
         return Err(err);
     }
 
-    // TODO(b/191845268): microdroid_manager should use this binder to communicate with the host
-    if let Err(err) = get_vms_rpc_binder() {
-        error!("cannot connect to VirtualMachineService: {}", err);
-    }
+    let service = get_vms_rpc_binder().expect("cannot connect to VirtualMachineService");
 
     if !metadata.payload_config_path.is_empty() {
         let config = load_config(Path::new(&metadata.payload_config_path))?;
@@ -87,7 +106,7 @@
 
         // TODO(jooyung): wait until sys.boot_completed?
         if let Some(main_task) = &config.task {
-            exec_task(main_task).map_err(|e| {
+            exec_task(main_task, &service).map_err(|e| {
                 error!("failed to execute task: {}", e);
                 e
             })?;
@@ -118,29 +137,13 @@
 
 /// Executes the given task. Stdout of the task is piped into the vsock stream to the
 /// virtualizationservice in the host side.
-fn exec_task(task: &Task) -> Result<()> {
-    const VMADDR_CID_HOST: u32 = 2;
-    const PORT_VIRT_SVC: u32 = 3000;
-    let stdout = match VsockStream::connect_with_cid_port(VMADDR_CID_HOST, PORT_VIRT_SVC) {
-        Ok(stream) => {
-            // SAFETY: the ownership of the underlying file descriptor is transferred from stream
-            // to the file object, and then into the Command object. When the command is finished,
-            // the file descriptor is closed.
-            let f = unsafe { File::from_raw_fd(stream.into_raw_fd()) };
-            Stdio::from(f)
-        }
-        Err(e) => {
-            error!("failed to connect to virtualization service: {}", e);
-            // Don't fail hard here. Even if we failed to connect to the virtualizationservice,
-            // we keep executing the task. This can happen if the owner of the VM doesn't register
-            // callback to accept the stream. Use /dev/null as the stdout so that the task can
-            // make progress without waiting for someone to consume the output.
-            Stdio::null()
-        }
-    };
+fn exec_task(task: &Task, service: &Strong<dyn IVirtualMachineService>) -> Result<()> {
     info!("executing main task {:?}...", task);
-    // TODO(jiyong): consider piping the stream into stdio (and probably stderr) as well.
-    let mut child = build_command(task)?.stdout(stdout).spawn()?;
+    let mut child = build_command(task)?.spawn()?;
+
+    info!("notifying payload started");
+    service.notifyPayloadStarted(get_local_cid()? as i32)?;
+
     match child.wait()?.code() {
         Some(0) => {
             info!("task successfully finished");
@@ -152,7 +155,10 @@
 }
 
 fn build_command(task: &Task) -> Result<Command> {
-    Ok(match task.type_ {
+    const VMADDR_CID_HOST: u32 = 2;
+    const PORT_VIRT_SVC: u32 = 3000;
+
+    let mut command = match task.type_ {
         TaskType::Executable => {
             let mut command = Command::new(&task.command);
             command.args(&task.args);
@@ -163,7 +169,30 @@
             command.arg(find_library_path(&task.command)?).args(&task.args);
             command
         }
-    })
+    };
+
+    match VsockStream::connect_with_cid_port(VMADDR_CID_HOST, PORT_VIRT_SVC) {
+        Ok(stream) => {
+            // SAFETY: the ownership of the underlying file descriptor is transferred from stream
+            // to the file object, and then into the Command object. When the command is finished,
+            // the file descriptor is closed.
+            let file = unsafe { File::from_raw_fd(stream.into_raw_fd()) };
+            command
+                .stdin(Stdio::from(file.try_clone()?))
+                .stdout(Stdio::from(file.try_clone()?))
+                .stderr(Stdio::from(file));
+        }
+        Err(e) => {
+            error!("failed to connect to virtualization service: {}", e);
+            // Don't fail hard here. Even if we failed to connect to the virtualizationservice,
+            // we keep executing the task. This can happen if the owner of the VM doesn't register
+            // callback to accept the stream. Use /dev/null as the stream so that the task can
+            // make progress without waiting for someone to consume the output.
+            command.stdin(Stdio::null()).stdout(Stdio::null()).stderr(Stdio::null());
+        }
+    }
+
+    Ok(command)
 }
 
 fn find_library_path(name: &str) -> Result<String> {
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
index 7bb18a4..c7a1471 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
@@ -23,14 +23,13 @@
  */
 oneway interface IVirtualMachineCallback {
     /**
-     * Called when the payload starts in the VM. `stdout` is the stdout of the payload.
+     * Called when the payload starts in the VM. `stream` is the input/output port of the payload.
      *
      * <p>Note: when the virtual machine object is shared to multiple processes and they register
-     * this callback to the same virtual machine object, the processes will compete to read from the
-     * same payload stdout. As a result, each process might get only a part of the entire output
-     * stream. To avoid such a case, keep only one process to read from the stdout.
+     * this callback to the same virtual machine object, the processes will compete to access the
+     * same payload stream. Keep only one process to access the stream.
      */
-    void onPayloadStarted(int cid, in ParcelFileDescriptor stdout);
+    void onPayloadStarted(int cid, in @nullable ParcelFileDescriptor stream);
 
     /**
      * Called when the VM dies.
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index e85ac2c..ab410d3 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -52,7 +52,7 @@
 use std::path::{Path, PathBuf};
 use std::sync::{Arc, Mutex, Weak};
 use vmconfig::VmConfig;
-use vsock::{VsockListener, SockAddr, VsockStream};
+use vsock::{SockAddr, VsockListener, VsockStream};
 use zip::ZipArchive;
 
 pub const BINDER_SERVICE_IDENTIFIER: &str = "android.system.virtualizationservice";
@@ -64,8 +64,8 @@
 const VMADDR_CID_HOST: u32 = 2;
 
 /// Port number that virtualizationservice listens on connections from the guest VMs for the
-/// payload output
-const PORT_VIRT_SERVICE: u32 = 3000;
+/// payload input and output
+const PORT_VIRT_STREAM_SERVICE: u32 = 3000;
 
 /// Port number that virtualizationservice listens on connections from the guest VMs for the
 /// VirtualMachineService binder service
@@ -286,7 +286,7 @@
         // server for payload output
         let state = service.state.clone(); // reference to state (not the state itself) is copied
         std::thread::spawn(move || {
-            handle_connection_from_vm(state).unwrap();
+            handle_stream_connection_from_vm(state).unwrap();
         });
 
         // binder server for vm
@@ -316,8 +316,8 @@
 
 /// Waits for incoming connections from VM. If a new connection is made, notify the event to the
 /// client via the callback (if registered).
-fn handle_connection_from_vm(state: Arc<Mutex<State>>) -> Result<()> {
-    let listener = VsockListener::bind_with_cid_port(VMADDR_CID_HOST, PORT_VIRT_SERVICE)?;
+fn handle_stream_connection_from_vm(state: Arc<Mutex<State>>) -> Result<()> {
+    let listener = VsockListener::bind_with_cid_port(VMADDR_CID_HOST, PORT_VIRT_STREAM_SERVICE)?;
     for stream in listener.incoming() {
         let stream = match stream {
             Err(e) => {
@@ -329,14 +329,11 @@
         if let Ok(SockAddr::Vsock(addr)) = stream.peer_addr() {
             let cid = addr.cid();
             let port = addr.port();
-            info!("connected from cid={}, port={}", cid, port);
-            if cid < FIRST_GUEST_CID {
-                warn!("connection is not from a guest VM");
-                continue;
-            }
-            // TODO(b/191845268): handle this with VirtualMachineService
+            info!("payload stream connected from cid={}, port={}", cid, port);
             if let Some(vm) = state.lock().unwrap().get_vm(cid) {
-                vm.callbacks.notify_payload_started(cid, stream);
+                vm.stream.lock().unwrap().insert(stream);
+            } else {
+                error!("connection from cid={} is not from a guest VM", cid);
             }
         }
     }
@@ -603,11 +600,11 @@
 
 impl VirtualMachineCallbacks {
     /// Call all registered callbacks to notify that the payload has started.
-    pub fn notify_payload_started(&self, cid: Cid, stream: VsockStream) {
+    pub fn notify_payload_started(&self, cid: Cid, stream: Option<VsockStream>) {
         let callbacks = &*self.0.lock().unwrap();
-        let pfd = vsock_stream_to_pfd(stream);
+        let pfd = stream.map(vsock_stream_to_pfd);
         for callback in callbacks {
-            if let Err(e) = callback.onPayloadStarted(cid as i32, &pfd) {
+            if let Err(e) = callback.onPayloadStarted(cid as i32, pfd.as_ref()) {
                 error!("Error notifying payload start event from VM CID {}: {}", cid, e);
             }
         }
@@ -748,15 +745,18 @@
 impl IVirtualMachineService for VirtualMachineService {
     fn notifyPayloadStarted(&self, cid: i32) -> binder::Result<()> {
         let cid = cid as Cid;
-        if self.state.lock().unwrap().get_vm(cid).is_none() {
+        if let Some(vm) = self.state.lock().unwrap().get_vm(cid) {
+            info!("VM having CID {} started payload", cid);
+            let stream = vm.stream.lock().unwrap().take();
+            vm.callbacks.notify_payload_started(cid, stream);
+            Ok(())
+        } else {
             error!("notifyPayloadStarted is called from an unknown cid {}", cid);
-            return Err(new_binder_exception(
+            Err(new_binder_exception(
                 ExceptionCode::SERVICE_SPECIFIC,
                 format!("cannot find a VM with cid {}", cid),
-            ));
+            ))
         }
-        info!("VM having CID {} started payload", cid);
-        Ok(())
     }
 }
 
diff --git a/virtualizationservice/src/crosvm.rs b/virtualizationservice/src/crosvm.rs
index 5873cd9..5984ff0 100644
--- a/virtualizationservice/src/crosvm.rs
+++ b/virtualizationservice/src/crosvm.rs
@@ -26,8 +26,9 @@
 use std::path::PathBuf;
 use std::process::Command;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread;
+use vsock::VsockStream;
 
 const CROSVM_PATH: &str = "/apex/com.android.virt/bin/crosvm";
 
@@ -73,6 +74,8 @@
     running: AtomicBool,
     /// Callbacks to clients of the VM.
     pub callbacks: VirtualMachineCallbacks,
+    /// Input/output stream of the payload run in the VM.
+    pub stream: Mutex<Option<VsockStream>>,
 }
 
 impl VmInstance {
@@ -96,6 +99,7 @@
             requester_debug_pid,
             running: AtomicBool::new(true),
             callbacks: Default::default(),
+            stream: Mutex::new(None),
         }
     }
 
diff --git a/vm/src/run.rs b/vm/src/run.rs
index 8db43fb..6eb88e9 100644
--- a/vm/src/run.rs
+++ b/vm/src/run.rs
@@ -163,16 +163,22 @@
 impl Interface for VirtualMachineCallback {}
 
 impl IVirtualMachineCallback for VirtualMachineCallback {
-    fn onPayloadStarted(&self, _cid: i32, stdout: &ParcelFileDescriptor) -> BinderResult<()> {
-        // Show the stdout of the payload
-        let mut reader = BufReader::new(stdout.as_ref());
-        loop {
-            let mut s = String::new();
-            match reader.read_line(&mut s) {
-                Ok(0) => break,
-                Ok(_) => print!("{}", s),
-                Err(e) => eprintln!("error reading from virtual machine: {}", e),
-            };
+    fn onPayloadStarted(
+        &self,
+        _cid: i32,
+        stream: Option<&ParcelFileDescriptor>,
+    ) -> BinderResult<()> {
+        // Show the output of the payload
+        if let Some(stream) = stream {
+            let mut reader = BufReader::new(stream.as_ref());
+            loop {
+                let mut s = String::new();
+                match reader.read_line(&mut s) {
+                    Ok(0) => break,
+                    Ok(_) => print!("{}", s),
+                    Err(e) => eprintln!("error reading from virtual machine: {}", e),
+                };
+            }
         }
         Ok(())
     }