pvmfw: apply_debug_policy: Improve failure path
As the function already makes an internal backup of the debug_policy,
turn the parameter into a shareable reference and pass the backup to
fdt_apply_overlay instead of the original DTBO. This removes the need to
do any work to restore the overlay on failure.
Avoid confusing logs such as
[ERROR] Failed to apply debug policy: The requested node or property does not exist. Recovering...
[INFO] Debug policy applied.
by returning a bool letting the caller know if DP was properly applied.
Report failure to apply DP as warnings instead of info! or error!.
Bug: 280425124
Test: atest MicrodroidHostTests
Change-Id: Ib5979b07c7978edd94dd90537faefebd25620b19
Merged-In: Ib5979b07c7978edd94dd90537faefebd25620b19
diff --git a/pvmfw/src/fdt.rs b/pvmfw/src/fdt.rs
index 70916ac..b3ce483 100644
--- a/pvmfw/src/fdt.rs
+++ b/pvmfw/src/fdt.rs
@@ -41,6 +41,7 @@
use log::debug;
use log::error;
use log::info;
+use log::warn;
use tinyvec::ArrayVec;
/// Extract from /config the address range containing the pre-loaded kernel. Absence of /config is
@@ -729,8 +730,9 @@
set_or_clear_chosen_flag(fdt, cstr!("avf,new-instance"), new_instance)?;
if let Some(debug_policy) = debug_policy {
- apply_debug_policy(fdt, debug_policy)?;
- info!("Debug policy applied.");
+ if apply_debug_policy(fdt, debug_policy)? {
+ info!("Debug policy applied.");
+ }
} else {
info!("No debug policy found.");
}
@@ -774,27 +776,31 @@
Ok(())
}
-fn apply_debug_policy(fdt: &mut Fdt, debug_policy: &mut [u8]) -> libfdt::Result<()> {
+/// Apply the debug policy overlay to the guest DT.
+///
+/// Returns Ok(true) on success, Ok(false) on recovered failure and Err(_) on corruption of the DT.
+fn apply_debug_policy(fdt: &mut Fdt, debug_policy: &[u8]) -> libfdt::Result<bool> {
let backup_fdt = Vec::from(fdt.as_slice());
- let overlay = match Fdt::from_mut_slice(debug_policy) {
+ let mut debug_policy = Vec::from(debug_policy);
+ let overlay = match Fdt::from_mut_slice(debug_policy.as_mut_slice()) {
Ok(overlay) => overlay,
Err(e) => {
- info!("Corrupted debug policy found: {e}. Not applying.");
- return Ok(());
+ warn!("Corrupted debug policy found: {e}. Not applying.");
+ return Ok(false);
}
};
- let backup_overlay = Vec::from(overlay.as_slice());
- // SAFETY - on failure, the corrupted fdts are discarded and are restored using the backups.
+ // SAFETY - on failure, the corrupted DT is restored using the backup.
if let Err(e) = unsafe { fdt.apply_overlay(overlay) } {
- error!("Failed to apply debug policy: {e}. Recovering...");
+ warn!("Failed to apply debug policy: {e}. Recovering...");
fdt.copy_from_slice(backup_fdt.as_slice())?;
- overlay.copy_from_slice(backup_overlay.as_slice())?;
// A successful restoration is considered success because an invalid debug policy
// shouldn't DOS the pvmfw
+ Ok(false)
+ } else {
+ Ok(true)
}
- Ok(())
}
fn read_common_debug_policy(fdt: &Fdt, debug_feature_name: &CStr) -> libfdt::Result<bool> {
