crosvm: support VM shutdown via SystemEvent

ARM systems don't have an exit event fd like x86, instead one of the Vcpus
will exit with the SystemEvent reason and put a code into the kvm run
union of either shutdown, reboot, or crash.  We currently don't handle
reboot or crash differently but can do so in the future.

BUG=chromium:797868
TEST=./build_test passes on all architectures
TEST=crosvm runs on kevin - manually test shutdown via maitred

Change-Id: I455cbe1ac653f61a1e9eae1ce22922d14cff4e3c
Reviewed-on: https://chromium-review.googlesource.com/982531
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/linux.rs b/src/linux.rs
index e599740..0ea188b 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -468,6 +468,9 @@ fn run_vcpu(vcpu: Vcpu,
                             }
                             VcpuExit::Hlt => break,
                             VcpuExit::Shutdown => break,
+                            VcpuExit::SystemEvent(_, _) =>
+                                //TODO handle reboot and crash events
+                                kill_signaled.store(true, Ordering::SeqCst),
                             r => warn!("unexpected vcpu exit: {:?}", r),
                         }
                     }