Make QEMU exit when a test panics (#19)

This PR submitted by @HadrienG2 makes QEMU exit with an error code when a panic happens. This is done by using the ISA debug port.

Should help with running tests automatically.

uefi-services/Cargo.toml

@@ -7,8 +7,14 @@ edition = "2018"
 
 [dependencies]
 rlibc = "1"
+x86_64 = "0.2"
 
 uefi = { path = ".." }
 uefi-alloc = { path = "../uefi-alloc" }
 uefi-logger = { path = "../uefi-logger" }
 log = { version = "0.4", default-features = false }
+
+[features]
+# Signals the implementation that QEMU's exit port hack is enabled and assigned
+# to the f4 CPU port.
+qemu-f4-exit = []

uefi-services/src/lib.rs

@@ -92,6 +92,8 @@ fn init_alloc() {
     uefi_alloc::init(st.boot);
 }
 
+
+
 #[lang = "eh_personality"]
 fn eh_personality() {}
 
@@ -104,9 +106,35 @@ fn panic_handler(info: &core::panic::PanicInfo) -> ! {
         }
     }
 
-    loop {
-        // TODO: add a timeout then shutdown.
+    // Give the user some time to read the message
+    if let Some(st) = unsafe { SYSTEM_TABLE } {
+        // FIXME: Check if boot-time services have been exited too
+        st.boot.stall(10_000_000);
+    } else {
+        let mut dummy = 0u64;
+        // FIXME: May need different counter values in debug & release builds
+        for i in 0..300_000_000 {
+            unsafe { core::ptr::write_volatile(&mut dummy, i); }
+        }
+    }
+
+    // If running inside of QEMU and the f4 port hack is enabled, use it to
+    // signal the error to the parent shell and exit
+    if cfg!(feature = "qemu-f4-exit") {
+        use x86_64::instructions::port::Port;
+        let mut port = Port::<u32>::new(0xf4);
+        unsafe { port.write(42); }
     }
+
+    // If the system table is available, use UEFI's standard shutdown mechanism
+    if let Some(st) = unsafe { SYSTEM_TABLE } {
+        use uefi::table::runtime::ResetType;
+        st.runtime.reset(ResetType::Shutdown, uefi::Status::Aborted, None)
+    }
+
+    // If we don't have any shutdown mechanism handy, the best we can do is loop
+    error!("Could not shut down, please power off the system manually...");
+    loop { }
 }
 
 #[alloc_error_handler]

uefi-test-runner/Cargo.toml

@@ -11,3 +11,6 @@ uefi-services = { path = "../uefi-services" }
 uefi-exts = { path = "../uefi-exts" }
 
 log = { version = "0.4", default-features = false }
+
+[features]
+qemu-f4-exit = ["uefi-services/qemu-f4-exit"]

uefi-test-runner/build.py

@@ -41,10 +41,10 @@ def run_xbuild(*flags):
 
     sp.run(cmd).check_returncode()
 
-def build():
+def build(*test_flags):
     'Builds the tests and examples.'
 
-    run_xbuild('--package', 'uefi-test-runner')
+    run_xbuild('--package', 'uefi-test-runner', *test_flags)
     run_xbuild('--package', 'uefi', '--examples')
 
     # Copy the built test runner file to the right directory for running tests.
@@ -72,7 +72,7 @@ def run_qemu():
     'Runs the code in QEMU.'
 
     # Rebuild all the changes.
-    build()
+    build('--features', 'qemu-f4-exit')
 
     ovmf_code, ovmf_vars = OVMF_DIR / 'OVMF_CODE.fd', OVMF_DIR / 'OVMF_VARS.fd'
 
@@ -105,6 +105,9 @@ def run_qemu():
         # Mount the built examples directory.
         '-drive', f'format=raw,file=fat:rw:{examples_dir}',
 
+        # Map the QEMU exit signal to port f4
+        '-device', 'isa-debug-exit,iobase=0xf4,iosize=0x04',
+
         # OVMF debug builds can output information to a serial `debugcon`.
         # Only enable when debugging UEFI boot:
         #'-debugcon', 'file:debug.log', '-global', 'isa-debugcon.iobase=0x402',