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[PATCH v1] migration/postcopy: ensure preempt channel is ready before lo
From: |
Wei Wang |
Subject: |
[PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states |
Date: |
Thu, 4 Apr 2024 18:05:50 +0800 |
Before loading the guest states, ensure that the preempt channel has been
ready to use, as some of the states (e.g. via virtio_load) might trigger
page faults that will be handled through the preempt channel. So yield to
the main thread in the case that the channel create event has been
dispatched.
Originally-by: Lei Wang <lei4.wang@intel.com>
Link:
9aa5d1be-7801-40dd-83fd-f7e041ced249@intel.com/T/">https://lore.kernel.org/all/9aa5d1be-7801-40dd-83fd-f7e041ced249@intel.com/T/
Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Lei Wang <lei4.wang@intel.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
migration/savevm.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/migration/savevm.c b/migration/savevm.c
index 388d7af7cd..fbc9f2bdd4 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2342,6 +2342,23 @@ static int
loadvm_handle_cmd_packaged(MigrationIncomingState *mis)
QEMUFile *packf = qemu_file_new_input(QIO_CHANNEL(bioc));
+ /*
+ * Before loading the guest states, ensure that the preempt channel has
+ * been ready to use, as some of the states (e.g. via virtio_load) might
+ * trigger page faults that will be handled through the preempt channel.
+ * So yield to the main thread in the case that the channel create event
+ * has been dispatched.
+ */
+ do {
+ if (!migrate_postcopy_preempt() || !qemu_in_coroutine() ||
+ mis->postcopy_qemufile_dst) {
+ break;
+ }
+
+ aio_co_schedule(qemu_get_current_aio_context(), qemu_coroutine_self());
+ qemu_coroutine_yield();
+ } while (!qemu_sem_timedwait(&mis->postcopy_qemufile_dst_done, 1));
+
ret = qemu_loadvm_state_main(packf, mis);
trace_loadvm_handle_cmd_packaged_main(ret);
qemu_fclose(packf);
--
2.27.0
- [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states,
Wei Wang <=
- Re: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Peter Xu, 2024/04/04
- RE: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Wang, Wei W, 2024/04/04
- Re: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Wang, Lei, 2024/04/04
- Re: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Peter Xu, 2024/04/04
- RE: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Wang, Wei W, 2024/04/04
- Re: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Peter Xu, 2024/04/04
- RE: [PATCH v1] migration/postcopy: ensure preempt channel is ready before loading states, Wang, Wei W, 2024/04/04