Start on pVM firmware in Rust.

For now it is just the Rust entry point. This needs to be linked against
some assembly code to initialise everything first.

Bug: 223166344
Test: m libpvmfw
Change-Id: I50a29a59a1aa60afb8a8ecc7db7fc57eb2a47c4b
diff --git a/pvmfw/src/main.rs b/pvmfw/src/main.rs
new file mode 100644
index 0000000..0a359f6
--- /dev/null
+++ b/pvmfw/src/main.rs
@@ -0,0 +1,37 @@
+// 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.
+
+//! pVM firmware.
+
+#![no_main]
+#![no_std]
+
+mod psci;
+
+use core::panic::PanicInfo;
+use psci::{system_off, system_reset};
+
+/// Entry point for pVM firmware.
+#[no_mangle]
+pub extern "C" fn main() -> ! {
+    system_off();
+    #[allow(clippy::empty_loop)]
+    loop {}
+}
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    system_reset();
+    loop {}
+}