On 29.01.19 17:54, Pierre Morel wrote: > On 29/01/2019 16:14, David Hildenbrand wrote: >> On 29.01.19 14:31, Pierre Morel wrote: >>> On 21/01/2019 14:42, David Hildenbrand wrote: >>>> PCI on s390x is really weird and how it was modeled in QEMU might not have >>>> been the right choice. Anyhow, right now it is the case that: >>>> - Hotplugging a PCI device will silently create a zPCI device >>>> (if none is provided) >>>> - Hotunplugging a zPCI device will unplug the PCI device (if any) >>>> - Hotunplugging a PCI device will unplug also the zPCI device >>>> As far as I can see, we can no longer change this behavior. But we >>>> should fix it. > > >>> So unplugging PCI first will deny the guest any possibility to smoothly >>> relinquish a device. >>> >>> >>> Is it possible the other way around? >> >> Maybe, but it does not really matter. We unplug both devices >> synchronously, without the guest recognizing the order. We always have >> the unplug request first that notifies the guest. When we get an ACK >> from the guest, we can unpplug both devices in any order. >> >> (and if we want to change the order, we should do it in a separate >> patch, this patch does not change the order, just refactors the code) > > > If it is done atomically, then I have no objection.
Yes, this is atomically. It is two separate steps, but only logically. The guest cannot observe it. Thanks! > > Regards, > Pierre > > > -- Thanks, David / dhildenb