cause triple fault on panic

tee/supervisor-tdx/src/panic.rs

@@ -1,9 +1,18 @@
+use core::arch::asm;
 use core::panic::PanicInfo;
 
 use log::error;
 
 #[panic_handler]
 fn panic_handler(info: &PanicInfo) -> ! {
     error!("{info}");
-    loop {}
+    triple_fault();
+}
+
+fn triple_fault() -> ! {
+    // We don't have an exception handler for int3 or double faults, so this
+    // will cause a triple fault.
+    unsafe {
+        asm!("int3", options(noreturn));
+    }
 }