vmm: Cache guest events in a buffer of size 20

vmm/rpc/proto/vmm_rpc.proto

@@ -35,6 +35,15 @@ message VmInfo {
   string shutdown_progress = 12;
   // Image version
   string image_version = 13;
+  // Events
+  repeated GuestEvent events = 14;
+}
+
+message GuestEvent {
+  string event = 1;
+  string body = 2;
+  // Timestamp in milliseconds since Unix epoch
+  uint64 timestamp = 3;
 }
 
 message Id {

vmm/src/app.rs

@@ -17,10 +17,11 @@ use id_pool::IdPool;
 use ra_rpc::client::RaClient;
 use serde::{Deserialize, Serialize};
 use serde_json::json;
-use std::collections::{BTreeSet, HashMap};
+use std::collections::{BTreeSet, HashMap, VecDeque};
 use std::net::IpAddr;
 use std::path::{Path, PathBuf};
 use std::sync::{Arc, Mutex, MutexGuard};
+use std::time::SystemTime;
 use supervisor_client::SupervisorClient;
 use tracing::{error, info};
 
@@ -411,6 +412,17 @@ impl App {
         let Some(vm) = state.vms.values_mut().find(|vm| vm.config.cid == cid) else {
             bail!("VM not found");
         };
+        vm.state.events.push_back(pb::GuestEvent {
+            event: event.into(),
+            body: body.clone(),
+            timestamp: SystemTime::now()
+                .duration_since(SystemTime::UNIX_EPOCH)
+                .unwrap_or_default()
+                .as_millis() as u64,
+        });
+        while vm.state.events.len() > self.config.event_buffer_size {
+            vm.state.events.pop_front();
+        }
         match event {
             "boot.progress" => {
                 vm.state.boot_progress = body;
@@ -648,6 +660,7 @@ struct VmStateMut {
     boot_error: String,
     shutdown_progress: String,
     devices: GpuConfig,
+    events: VecDeque<pb::GuestEvent>,
 }
 
 impl VmStateMut {

vmm/src/app/qemu.rs

@@ -51,6 +51,7 @@ pub struct VmInfo {
     pub shutdown_progress: String,
     pub image_version: String,
     pub gateway_enabled: bool,
+    pub events: Vec<pb::GuestEvent>,
 }
 
 #[derive(Debug, Builder)]
@@ -177,6 +178,7 @@ impl VmInfo {
             app_id: self.manifest.app_id.clone(),
             instance_id: self.instance_id.as_deref().map(Into::into),
             exited_at: self.exited_at.clone(),
+            events: self.events.clone(),
         }
     }
 }
@@ -222,6 +224,7 @@ impl VmState {
             shutdown_progress: self.state.shutdown_progress.clone(),
             image_version: self.config.image.info.version.clone(),
             gateway_enabled: self.config.gateway_enabled,
+            events: self.state.events.clone().into(),
         }
     }
 }

vmm/src/config.rs

@@ -269,6 +269,9 @@ pub struct Config {
     #[serde(default)]
     pub node_name: String,
 
+    /// The buffer size in VMM process for guest events
+    pub event_buffer_size: usize,
+
     /// CVM configuration
     pub cvm: CvmConfig,
     /// Gateway configuration

vmm/vmm.toml

@@ -11,6 +11,7 @@ log_level = "debug"
 address = "unix:./vmm.sock"
 reuse = true
 kms_url = "http://127.0.0.1:8081"
+event_buffer_size = 20
 
 [cvm]
 qemu_path = ""