On Saturday, April 6, 2024 5:53 AM, Peter Xu wrote:
> On Fri, Apr 05, 2024 at 11:40:56AM +0800, Wei Wang 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-f7e041ced249@intel
> > .com/T/
> > Suggested-by: Peter Xu <pet...@redhat.com>
>
> The current version doesn't have any of my credits. :) Thanks, but I'll just
> drop
> it to reflect reality, so we keep the credit to the right ones.
>
> > 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.
>
> I'll squash below into it. If any of you disagree please shoot: valid until
> this
> Sunday.
>
> + * 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.
>
Looks good to me.
