commit 9515d0fc2d7da3564f6e2a908b372c6f14395853
author Pierre-Clément Tosi <ptosi@google.com> Mon Apr 15 15:58:07 2024 +0100
committer Elie Kheirallah <khei@google.com> Tue Nov 12 23:34:15 2024 +0000
tree a9491493a43f55a0812b7e9f73060d2193436716
parent 93a422f4b5e464f6d96974f82dfadfd5a147d385

virtmgr: Support dumping guest DT for debugging

Give a way to make crosvm dump the guest DT it generated without needing
to recompile and/or reinstall any part of the stack, by detecting the
newly-introduced boolean system property

    hypervisor.virtualizationmanager.dump_device_tree

which can be set on devices being debugged.
Note: this propery is redundant if you pass a path to dump the device
tree using --dump-device-tree

Bug: 335160369
Test: m virtmgr && TH
Test: adb shell setprop
hypervisor.virtualizationmanager.dump_device_tree true && /apex/.../vm
run-microdroid && check
/data/misc/virtualizationservice/CID/device_tree.dtb exists

Change-Id: I71ba56f14812ccb9bc5dab1ad3789656aa9a8460

android/virtmgr/src/aidl.rs

diff --git a/android/virtmgr/src/aidl.rs b/android/virtmgr/src/aidl.rs
index 87d7a88..4555ebc 100644
--- a/android/virtmgr/src/aidl.rs
+++ b/android/virtmgr/src/aidl.rs
@@ -534,7 +534,13 @@
             clone_or_prepare_logger_fd(console_out_fd, format!("Console({})", cid))?;
         let console_in_fd = console_in_fd.map(clone_file).transpose()?;
         let log_fd = clone_or_prepare_logger_fd(log_fd, format!("Log({})", cid))?;
-        let dump_dt_fd = dump_dt_fd.map(clone_file).transpose()?;
+        let dump_dt_fd = if let Some(fd) = dump_dt_fd {
+            Some(clone_file(fd)?)
+        } else if debug_config.dump_device_tree {
+            Some(prepare_dump_dt_file(&temporary_directory)?)
+        } else {
+            None
+        };
 
         // Counter to generate unique IDs for temporary image files.
         let mut next_temporary_image_id = 0;
@@ -1669,6 +1675,16 @@
     Ok(ramdump)
 }
 
+/// Create the empty device tree dump file
+fn prepare_dump_dt_file(temporary_directory: &Path) -> binder::Result<File> {
+    let path = temporary_directory.join("device_tree.dtb");
+    let file = File::create(path)
+        .context("Failed to prepare device tree dump file")
+        .with_log()
+        .or_service_specific_exception(-1)?;
+    Ok(file)
+}
+
 fn is_protected(config: &VirtualMachineConfig) -> bool {
     match config {
         VirtualMachineConfig::RawConfig(config) => config.protectedVm,

android/virtmgr/src/debug_config.rs

diff --git a/android/virtmgr/src/debug_config.rs b/android/virtmgr/src/debug_config.rs
index 74559de..6e2bfef 100644
--- a/android/virtmgr/src/debug_config.rs
+++ b/android/virtmgr/src/debug_config.rs
@@ -30,6 +30,7 @@
 
 const CUSTOM_DEBUG_POLICY_OVERLAY_SYSPROP: &str =
     "hypervisor.virtualizationmanager.debug_policy.path";
+const DUMP_DT_SYSPROP: &str = "hypervisor.virtualizationmanager.dump_device_tree";
 const DEVICE_TREE_EMPTY_TREE_SIZE_BYTES: usize = 100; // rough estimation.
 
 struct DPPath {
@@ -183,6 +184,7 @@
 #[derive(Debug, Default)]
 pub struct DebugConfig {
     pub debug_level: DebugLevel,
+    pub dump_device_tree: bool,
     debug_policy: DebugPolicy,
 }
 
@@ -193,8 +195,13 @@
             info!("Debug policy is disabled");
             Default::default()
         });
+        let dump_dt_sysprop = system_properties::read_bool(DUMP_DT_SYSPROP, false);
+        let dump_device_tree = dump_dt_sysprop.unwrap_or_else(|e| {
+            warn!("Failed to read sysprop {DUMP_DT_SYSPROP}: {e}");
+            false
+        });
 
-        Self { debug_level, debug_policy }
+        Self { debug_level, debug_policy, dump_device_tree }
     }
 
     fn get_debug_policy() -> Option<DebugPolicy> {