Add onPayloadReady callback

The guest VM can notify that its payload has finished initialization and
is ready to serve its own services, by onPayloadReady callback.

Bug: 195381416
Test: atest MicrodroidHostTestCases
Change-Id: I67fee655c410342452bc5ee990e36dfecb30b0cb
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
index 4dc4333..15354a3 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
@@ -32,6 +32,11 @@
     void onPayloadStarted(int cid, in @nullable ParcelFileDescriptor stream);
 
     /**
+     * Called when the payload in the VM is ready to serve.
+     */
+    void onPayloadReady(int cid);
+
+    /**
      * Called when the payload has finished in the VM. `exitCode` is the exit code of the payload.
      */
     void onPayloadFinished(int cid, int exitCode);
diff --git a/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl b/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl
index 730f6c2..10b14e0 100644
--- a/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl
+++ b/virtualizationservice/aidl/android/system/virtualmachineservice/IVirtualMachineService.aidl
@@ -24,6 +24,12 @@
     void notifyPayloadStarted(int cid);
 
     /**
+     * Notifies that the payload is ready to serve.
+     * TODO(b/191845268): remove cid parameter
+     */
+    void notifyPayloadReady(int cid);
+
+    /**
      * Notifies that the payload has finished.
      * TODO(b/191845268): remove cid parameter
      */
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index 562843b..6b60da3 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -640,6 +640,16 @@
         }
     }
 
+    /// Call all registered callbacks to notify that the payload is ready to serve.
+    pub fn notify_payload_ready(&self, cid: Cid) {
+        let callbacks = &*self.0.lock().unwrap();
+        for callback in callbacks {
+            if let Err(e) = callback.onPayloadReady(cid as i32) {
+                error!("Error notifying payload ready event from VM CID {}: {}", cid, e);
+            }
+        }
+    }
+
     /// Call all registered callbacks to notify that the payload has finished.
     pub fn notify_payload_finished(&self, cid: Cid, exit_code: i32) {
         let callbacks = &*self.0.lock().unwrap();
@@ -799,6 +809,21 @@
         }
     }
 
+    fn notifyPayloadReady(&self, cid: i32) -> binder::Result<()> {
+        let cid = cid as Cid;
+        if let Some(vm) = self.state.lock().unwrap().get_vm(cid) {
+            info!("VM having CID {} payload is ready", cid);
+            vm.callbacks.notify_payload_ready(cid);
+            Ok(())
+        } else {
+            error!("notifyPayloadReady is called from an unknown cid {}", cid);
+            Err(new_binder_exception(
+                ExceptionCode::SERVICE_SPECIFIC,
+                format!("cannot find a VM with cid {}", cid),
+            ))
+        }
+    }
+
     fn notifyPayloadFinished(&self, cid: i32, exit_code: i32) -> binder::Result<()> {
         let cid = cid as Cid;
         if let Some(vm) = self.state.lock().unwrap().get_vm(cid) {