Revert "Revert "Handle exceptions.""

This reverts commit 81334588b1ccc9ce36ee5b95d38950d5e4dbb8f2.

Reason for revert: Relanding original change with fix.

Bug: 223166344
Test: Ran unprotected VM under crosvm.
Change-Id: Ia1a73afef6df10a8fecec8321233b4d8855329be
diff --git a/pvmfw/src/main.rs b/pvmfw/src/main.rs
index 4ab14b7..d38b1e3 100644
--- a/pvmfw/src/main.rs
+++ b/pvmfw/src/main.rs
@@ -18,6 +18,7 @@
 #![no_std]
 
 mod console;
+mod exceptions;
 mod psci;
 mod uart;