Re: [PATCH v2] device-assignment: Register as un-migratable

[Jan Kiszka <jan.kiszka@web.de>]

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Am 16.11.2010 00:24, Alex Williamson wrote:
> On Tue, 2010-11-16 at 00:11 +0100, Jan Kiszka wrote:
>> Am 16.11.2010 00:06, Alex Williamson wrote:
>>> Use register_device_unmigratable() to declare ourselves as
>>> non-migratable.
>>>
>>> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
>>> ---
>>>
>>>  v2: Use dummy vmsd instead of dummy save_state
>>>
>>>  hw/device-assignment.c |   10 ++++++++++
>>>  1 files changed, 10 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>>> index bde231d..154bb1a 100644
>>> --- a/hw/device-assignment.c
>>> +++ b/hw/device-assignment.c
>>> @@ -1434,6 +1434,10 @@ static void assigned_dev_unregister_msix_mmio(AssignedDevice *dev)
>>>      dev->msix_table_page = NULL;
>>>  }
>>>  
>>> +static const VMStateDescription vmstate_assigned_device = {
>>> +    .name = "pci-assign"
>>> +};
>>> +
>>>  static int assigned_initfn(struct PCIDevice *pci_dev)
>>>  {
>>>      AssignedDevice *dev = DO_UPCAST(AssignedDevice, dev, pci_dev);
>>> @@ -1490,6 +1494,11 @@ static int assigned_initfn(struct PCIDevice *pci_dev)
>>>  
>>>      assigned_dev_load_option_rom(dev);
>>>      QLIST_INSERT_HEAD(&devs, dev, next);
>>> +
>>> +    /* Register a vmsd so that we can mark it unmigratable. */
>>> +    vmstate_register(&dev->dev.qdev, 0, &vmstate_assigned_device, dev);
>>
>> Almost: You can register this vmstate description via assign_info
>> (.qdev.vmsd = ....).
> 
> Only if you have some other suggestion on where to call
> register_device_unmigratable rather than init.  qdev_init looks like
> this:
> 
> int qdev_init(DeviceState *dev)
> {
>     int rc;
> 
>     assert(dev->state == DEV_STATE_CREATED);
>     rc = dev->info->init(dev, dev->info);
>     if (rc < 0) {
>         qdev_free(dev);
>         return rc;
>     }
>     qemu_register_reset(qdev_reset, dev);
>     if (dev->info->vmsd) {
>         vmstate_register_with_alias_id(dev, -1, dev->info->vmsd, dev,
>                                        dev->instance_id_alias,
>                                        dev->alias_required_for_version);
>     }
>     dev->state = DEV_STATE_INITIALIZED;
>     return 0;
> }
> 
> So the save state entry hasn't been inserted yet for me to attach the
> no_migrate flag to from init :(

I see. I think that's a sign register_device_unmigratable should be
obsoleted as well by introducing no_migrate to vmstate (one day, vmsd ==
NULL could replace this flag).

BTW, ivshmem could resolve its need for dynamic no_migrate by
introducing two device types: one that is migratable (ivshmem-master)
and one that isn't (normal peer devices).

Jan


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