Move common VM functionality into a library.

Bug: 223166344
Test: Ran unprotected VM under crosvm.
Change-Id: I3b027c3a5de037c2adc75cf816518d8db5e10587
diff --git a/vmbase/src/power.rs b/vmbase/src/power.rs
new file mode 100644
index 0000000..10a5e5d
--- /dev/null
+++ b/vmbase/src/power.rs
@@ -0,0 +1,35 @@
+// 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.
+
+//! Functions for shutting down the VM.
+
+use psci::{system_off, system_reset};
+
+/// Makes a `PSCI_SYSTEM_OFF` call to shutdown the VM.
+///
+/// Panics if it returns an error.
+pub fn shutdown() -> ! {
+    system_off().unwrap();
+    #[allow(clippy::empty_loop)]
+    loop {}
+}
+
+/// Makes a `PSCI_SYSTEM_RESET` call to shutdown the VM abnormally.
+///
+/// Panics if it returns an error.
+pub fn reboot() -> ! {
+    system_reset().unwrap();
+    #[allow(clippy::empty_loop)]
+    loop {}
+}