Enable --extended-status for crosvm and return reason why VM died.

This will allow us to detect guest VM kernel panics because they can be
configured to reboot on panic.

Bug: 211704107
Test: Ran some VMs manually with vm tool
Change-Id: I3845bb9d569ad0dc098013b527b69b31352e7e08
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/DeathReason.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/DeathReason.aidl
new file mode 100644
index 0000000..2f454a9
--- /dev/null
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/DeathReason.aidl
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package android.system.virtualizationservice;
+
+/**
+ * The reason why a VM died.
+ */
+@Backing(type="int")
+enum DeathReason {
+    /** The VM requested to shut down. */
+    SHUTDOWN = 0,
+    /** The VM requested to reboot, possibly as the result of a kernel panic. */
+    REBOOT = 1,
+    /** The VM was killed. */
+    KILLED = 2,
+    /** The VM died for an unknown reason. */
+    UNKNOWN = 3,
+    /** There was an error waiting for the VM. */
+    INFRASTRUCTURE_ERROR = 4,
+}
diff --git a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
index aa8105f..12a056c 100644
--- a/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
+++ b/virtualizationservice/aidl/android/system/virtualizationservice/IVirtualMachineCallback.aidl
@@ -15,6 +15,8 @@
  */
 package android.system.virtualizationservice;
 
+import android.system.virtualizationservice.DeathReason;
+
 /**
  * An object which a client may register with the VirtualizationService to get callbacks about the
  * state of a particular VM.
@@ -50,5 +52,5 @@
      * Note that this will not be called if the VirtualizationService itself dies, so you should
      * also use `link_to_death` to handle that.
      */
-    void onDied(int cid);
+    void onDied(int cid, in DeathReason reason);
 }
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index c264270..5a7322b 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -22,6 +22,7 @@
 use ::binder::unstable_api::AsNative;
 use android_os_permissions_aidl::aidl::android::os::IPermissionController;
 use android_system_virtualizationservice::aidl::android::system::virtualizationservice::{
+    DeathReason::DeathReason,
     DiskImage::DiskImage,
     IVirtualMachine::{BnVirtualMachine, IVirtualMachine},
     IVirtualMachineCallback::IVirtualMachineCallback,
@@ -790,10 +791,10 @@
     }
 
     /// Call all registered callbacks to say that the VM has died.
-    pub fn callback_on_died(&self, cid: Cid) {
+    pub fn callback_on_died(&self, cid: Cid, reason: DeathReason) {
         let callbacks = &*self.0.lock().unwrap();
         for callback in callbacks {
-            if let Err(e) = callback.onDied(cid as i32) {
+            if let Err(e) = callback.onDied(cid as i32, reason) {
                 error!("Error notifying exit of VM CID {}: {}", cid, e);
             }
         }
diff --git a/virtualizationservice/src/crosvm.rs b/virtualizationservice/src/crosvm.rs
index 0b1429c..76f4f47 100644
--- a/virtualizationservice/src/crosvm.rs
+++ b/virtualizationservice/src/crosvm.rs
@@ -21,19 +21,24 @@
 use log::{debug, error, info};
 use shared_child::SharedChild;
 use std::fs::{remove_dir_all, File};
+use std::io;
 use std::mem;
 use std::num::NonZeroU32;
 use std::os::unix::io::{AsRawFd, RawFd};
 use std::path::PathBuf;
-use std::process::Command;
+use std::process::{Command, ExitStatus};
 use std::sync::{Arc, Mutex};
 use std::thread;
 use vsock::VsockStream;
+use android_system_virtualizationservice::aidl::android::system::virtualizationservice::DeathReason::DeathReason;
 use android_system_virtualmachineservice::binder::Strong;
 use android_system_virtualmachineservice::aidl::android::system::virtualmachineservice::IVirtualMachineService::IVirtualMachineService;
 
 const CROSVM_PATH: &str = "/apex/com.android.virt/bin/crosvm";
 
+/// The exit status which crosvm returns when a VM requests a reboot.
+const CROSVM_REBOOT_STATUS: i32 = 32;
+
 /// Configuration for a VM to run with crosvm.
 #[derive(Debug)]
 pub struct CrosvmConfig {
@@ -182,7 +187,8 @@
     /// This takes a separate reference to the `SharedChild` rather than using the one in
     /// `self.vm_state` to avoid holding the lock on `vm_state` while it is running.
     fn monitor(&self, child: Arc<SharedChild>) {
-        match child.wait() {
+        let result = child.wait();
+        match &result {
             Err(e) => error!("Error waiting for crosvm({}) instance to die: {}", child.id(), e),
             Ok(status) => info!("crosvm({}) exited with status {}", child.id(), status),
         }
@@ -192,7 +198,7 @@
         // Ensure that the mutex is released before calling the callbacks.
         drop(vm_state);
 
-        self.callbacks.callback_on_died(self.cid);
+        self.callbacks.callback_on_died(self.cid, death_reason(&result));
 
         // Delete temporary files.
         if let Err(e) = remove_dir_all(&self.temporary_directory) {
@@ -232,13 +238,31 @@
     }
 }
 
+fn death_reason(result: &Result<ExitStatus, io::Error>) -> DeathReason {
+    if let Ok(status) = result {
+        match status.code() {
+            None => DeathReason::KILLED,
+            Some(0) => DeathReason::SHUTDOWN,
+            Some(CROSVM_REBOOT_STATUS) => DeathReason::REBOOT,
+            Some(_) => DeathReason::UNKNOWN,
+        }
+    } else {
+        DeathReason::INFRASTRUCTURE_ERROR
+    }
+}
+
 /// Starts an instance of `crosvm` to manage a new VM.
 fn run_vm(config: CrosvmConfig) -> Result<SharedChild, Error> {
     validate_config(&config)?;
 
     let mut command = Command::new(CROSVM_PATH);
     // TODO(qwandor): Remove --disable-sandbox.
-    command.arg("run").arg("--disable-sandbox").arg("--cid").arg(config.cid.to_string());
+    command
+        .arg("--extended-status")
+        .arg("run")
+        .arg("--disable-sandbox")
+        .arg("--cid")
+        .arg(config.cid.to_string());
 
     if config.protected {
         command.arg("--protected-vm");