diff options
author | Stefan Hajnoczi <stefanha@redhat.com> | 2018-03-07 14:42:05 +0000 |
---|---|---|
committer | Stefan Hajnoczi <stefanha@redhat.com> | 2018-03-08 17:38:51 +0000 |
commit | 4486e89c219c0d1b9bd8dfa0b1dd5b0d51ff2268 (patch) | |
tree | 629e62ffd260635269f0fdcedd392256639c09cc /cpus.c | |
parent | 184b9623461e73ef79f5cebe68bdbcf2e4751e22 (diff) | |
download | qemu-4486e89c219c0d1b9bd8dfa0b1dd5b0d51ff2268.zip qemu-4486e89c219c0d1b9bd8dfa0b1dd5b0d51ff2268.tar.gz qemu-4486e89c219c0d1b9bd8dfa0b1dd5b0d51ff2268.tar.bz2 |
vl: introduce vm_shutdown()
Commit 00d09fdbbae5f7864ce754913efc84c12fdf9f1a ("vl: pause vcpus before
stopping iothreads") and commit dce8921b2baaf95974af8176406881872067adfa
("iothread: Stop threads before main() quits") tried to work around the
fact that emulation was still active during termination by stopping
iothreads. They suffer from race conditions:
1. virtio_scsi_handle_cmd_vq() racing with iothread_stop_all() hits the
virtio_scsi_ctx_check() assertion failure because the BDS AioContext
has been modified by iothread_stop_all().
2. Guest vq kick racing with main loop termination leaves a readable
ioeventfd that is handled by the next aio_poll() when external
clients are enabled again, resulting in unwanted emulation activity.
This patch obsoletes those commits by fully disabling emulation activity
when vcpus are stopped.
Use the new vm_shutdown() function instead of pause_all_vcpus() so that
vm change state handlers are invoked too. Virtio devices will now stop
their ioeventfds, preventing further emulation activity after vm_stop().
Note that vm_stop(RUN_STATE_SHUTDOWN) cannot be used because it emits a
QMP STOP event that may affect existing clients.
It is no longer necessary to call replay_disable_events() directly since
vm_shutdown() does so already.
Drop iothread_stop_all() since it is no longer used.
Cc: Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20180307144205.20619-5-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'cpus.c')
-rw-r--r-- | cpus.c | 16 |
1 files changed, 13 insertions, 3 deletions
@@ -993,7 +993,7 @@ void cpu_synchronize_all_pre_loadvm(void) } } -static int do_vm_stop(RunState state) +static int do_vm_stop(RunState state, bool send_stop) { int ret = 0; @@ -1002,7 +1002,9 @@ static int do_vm_stop(RunState state) pause_all_vcpus(); runstate_set(state); vm_state_notify(0, state); - qapi_event_send_stop(&error_abort); + if (send_stop) { + qapi_event_send_stop(&error_abort); + } } bdrv_drain_all(); @@ -1012,6 +1014,14 @@ static int do_vm_stop(RunState state) return ret; } +/* Special vm_stop() variant for terminating the process. Historically clients + * did not expect a QMP STOP event and so we need to retain compatibility. + */ +int vm_shutdown(void) +{ + return do_vm_stop(RUN_STATE_SHUTDOWN, false); +} + static bool cpu_can_run(CPUState *cpu) { if (cpu->stop) { @@ -1994,7 +2004,7 @@ int vm_stop(RunState state) return 0; } - return do_vm_stop(state); + return do_vm_stop(state, true); } /** |