On Friday, April 5, 2024 11:41 AM, Wang, Wei W wrote: > > 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. > > Originally-by: Lei Wang <lei4.w...@intel.com> > Link: https://lore.kernel.org/all/9aa5d1be-7801-40dd-83fd- > f7e041ced...@intel.com/T/ > Suggested-by: Peter Xu <pet...@redhat.com> > Signed-off-by: Lei Wang <lei4.w...@intel.com> > Signed-off-by: Wei Wang <wei.w.w...@intel.com> > --- > migration/savevm.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/migration/savevm.c b/migration/savevm.c index > 388d7af7cd..63f9991a8a 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 > + * hasn't 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 (1); > + > ret = qemu_loadvm_state_main(packf, mis); > trace_loadvm_handle_cmd_packaged_main(ret); > qemu_fclose(packf); > -- > 2.27.0
Main change from v1 is the drop of the wait on sem. It's still patched to loadvm_handle_cmd_packaged, as the sem issue (possible twice wait) isn't there now.
