OpenE2K/qemu-e2k
13
4
Fork 0
Code Issues 4 Pull Requests Projects 2 Releases Activity

migration/postcopy: ensure preempt channel is ready before loading states

Browse Source 
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 hasn't been
dispatched.

Cc: qemu-stable <qemu-stable@nongnu.org>
Fixes: 9358982744 ("migration: Send requested page directly in rp-return thread")
Originally-by: Lei Wang <lei4.wang@intel.com>
Link: https://lore.kernel.org/all/9aa5d1be-7801-40dd-83fd-f7e041ced249@intel.com/T/
Signed-off-by: Lei Wang <lei4.wang@intel.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Link: https://lore.kernel.org/r/20240405034056.23933-1-wei.w.wang@intel.com
[peterx: add a todo section, add Fixes and copy stable for 8.0+]
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Wei Wang 2024-04-05 11:40:56 +08:00 committed by Peter Xu
parent ce64e6224a
commit 7afbdada7e
1 changed files with 21 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
migration/savevm.c
View File

@ -2342,6 +2342,27 @@ static int loadvm_handle_cmd_packaged(MigrationIncomingState *mis)
QEMUFile *packf = qemu_file_new_input(QIO_CHANNEL(bioc)); 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
* hasn't been dispatched.
*
* TODO: if we can move migration loadvm out of main thread, then we
* won't block main thread from polling the accept() fds. We can drop
* this as a whole when that is done.
*/
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 (1);
ret = qemu_loadvm_state_main(packf, mis); ret = qemu_loadvm_state_main(packf, mis);
trace_loadvm_handle_cmd_packaged_main(ret); trace_loadvm_handle_cmd_packaged_main(ret);
qemu_fclose(packf); qemu_fclose(packf);