On Tue, 2010-10-05 at 15:49 -0500, Anthony Liguori wrote: > On 10/05/2010 03:46 PM, Alex Williamson wrote: > > On Tue, 2010-10-05 at 15:41 -0500, Anthony Liguori wrote: > > > >> On 10/05/2010 03:35 PM, Alex Williamson wrote: > >> > >>> I was thinking of making KVM VMs with assigned PCI devices > >>> unsavable/unmigratable, but I wasn't thrilled with the > >>> no_migrate solutions. The more generic solutions seems to be > >>> simply letting save handlers return an error if the device can't > >>> be migrated. This is also much more generic than a one-way > >>> bit flip of the no_migrate flag. For a vmsd based registration, > >>> the pre_save() routine seems to be the right place to allow > >>> devices to abort. The series also carries the error back through > >>> all the vmstate callers. If this looks good, I'll give it some > >>> more testing and submit as non-RFC. Thanks, > >>> > >>> > >> Doesn't this mean that we don't fail the migration until after > >> transferring all of the memory contents? > >> > > That's the case with the current no_migrate implementation too, it > > doesn't get called until qemu_savevm_state_complete(). Thanks, > > > > Ouch, that's unfortunate but also should be easily fixable. > > But making a save handler fail seems would make it impossible to get > instant failure semantics.
True. Ok, so maybe we do still need a separate no migrate registration. In any case, I think it's a good idea to allow the save routines to have a failure path, but I'll work on a way to disable migration that's not quite so coupled with the savevm entry (it seems silly for device assignment to register a savevm only for the purpose of then registering as non-migratable). Thanks, Alex
