use `crosvm resume` to detect RESTORE_COMPLETE

Instead of waiting for logcat output, run the `crosvm resume` command to
block until the vCPUs have begun.

CvdBootStateMachine starts a thread to run that command. When the
command completes, it notifies the other CvdBootStateMachine thread via
a pipe, which then sends a value to the `--daemon` parent indicating
that the restore is complete (using the same mechanism as for a normal
boot complete).

Bug: 333111958
Test: m && (stop_cvd; launch_cvd --noresume --enable-sandbox=false --daemon) && snapshot_util_cvd --subcmd=snapshot_take --auto_suspend --force --snapshot_path=$HOME/cf-snapshot && stop_cvd && launch_cvd --snapshot_path=$HOME/cf-snapshot
Change-Id: Ia515c0485a7d6ec5cda611a7423674422b9f28d5

1 files changed, 27 insertions, 0 deletions

diff --git a/host/libs/vm_manager/crosvm_manager.cpp b/host/libs/vm_manager/crosvm_manager.cpp
index c26da188e..899e39653 100644
--- a/host/libs/vm_manager/crosvm_manager.cpp
+++ b/host/libs/vm_manager/crosvm_manager.cpp
@@ -880,5 +880,32 @@ Result<std::vector<MonitorCommand>> CrosvmManager::StartCommands(
   return commands;
 }
 
+Result<void> CrosvmManager::WaitForRestoreComplete() const {
+  auto instance = CF_EXPECT(CuttlefishConfig::Get())->ForDefaultInstance();
+
+  // Wait for the control socket to exist. It is created early in crosvm's
+  // startup sequence, but the process may not even have been exec'd by CF at
+  // this point.
+  while (!FileExists(instance.CrosvmSocketPath())) {
+    usleep(50000);  // 50 ms, arbitrarily chosen
+  }
+
+  // Ask crosvm to resume the VM. crosvm promises to not complete this command
+  // until the vCPUs are started (even if it was never suspended to begin
+  // with).
+  auto infop = CF_EXPECT(Execute(
+      std::vector<std::string>{
+          instance.crosvm_binary(),
+          "resume",
+          instance.CrosvmSocketPath(),
+          "--full",
+      },
+      SubprocessOptions(), WEXITED));
+  CF_EXPECT_EQ(infop.si_code, CLD_EXITED);
+  CF_EXPECTF(infop.si_status == 0, "crosvm resume returns non zero code {}",
+             infop.si_status);
+  return {};
+}
+
 }  // namespace vm_manager
 }  // namespace cuttlefish