Re: [Qemu-devel] [ANNOUNCE] QEMU 1.5.0-rc2 is now available

["KONRAD Frédéric" <fred.konrad@greensocs.com>]

On 16/05/2013 16:21, mdroth wrote:
> On Wed, May 15, 2013 at 06:53:47PM -0500, Anthony Liguori wrote:
>> Hi,
>>
>> On behalf of the QEMU Team, I'd like to announce the availability of the
>> third release candidate for the QEMU 1.5 release.  This release is meant
>> for testing purposes and should not be used in a production environment.
>>
>> http://wiki.qemu.org/download/qemu-1.5.0-rc2.tar.bz2
>>
>> You can help improve the quality of the QEMU 1.5 release by testing this
>> release and reporting bugs on Launchpad:
>>
> Sorry to chime in on this so late in the cycle, but I just noticed what
> seems to be a pretty serious problem with migration to/from 1.4. This is
> the failure for 1.4 -> 1.5-rc2
>
> (qemu) migrate unix:/tmp/migrate.sock
> Unknown savevm section or instance '0000:00:03.0/virtio-net' 0
>
> Configuration:
>
> source: v14/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -L v14-bios -M
> pc-i440fx-1.4 -m 512M -kernel boot/vmlinuz-x86_64 -initrd
> boot/test-initramfs-x86_64.img.gz -vga std -append seed=1234 -drive
> file=disk1.img,if=virtio -drive file=disk2.img,if=virtio -net
> nic,model=virtio -net user -monitor unix:/tmp/vm-hmp.sock,server,nowait
> -qmp unix:/tmp/vm-qmp.sock,server,nowait -vnc :100
>
> target: v15rc2/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -L temp-bios
> -M pc-i440fx-1.4 -m 512M -kernel boot/vmlinuz-x86_64 -initrd
> boot/test-initramfs-x86_64.img.gz -vga std -append seed=1234 -drive
> file=disk1.img,if=virtio -drive file=disk2.img,if=virtio -net
> nic,model=virtio -net user -incoming unix:/tmp/migrate.sock -monitor
> unix:/tmp/vm-hmp-incoming.sock,server,nowait -qmp
> unix:/tmp/vm-qmp-incoming.sock,server,nowait -vnc :101
> QEMU 1.4.0 monitor - type 'help' for more information
>
> This seems to have been introduced with the virtio refactoring:
>
> commit e37da3945fa2fde161e1b217f937fc318c4b7639
> Author: KONRAD Frederic <fred.konrad@greensocs.com>
> Date:   Thu Apr 11 16:29:58 2013 +0200
>
>      virtio-net-pci: switch to the new API.
>      
>      Here the virtio-net-pci is modified for the new API. The device
>      virtio-net-pci extends virtio-pci. It creates and connects a
>      virtio-net-device during the init. The properties are not changed.
>      
>      Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
>      Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>      Message-id: 1365690602-22729-4-git-send-email-fred.konrad@greensocs.com
>      Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
>
> And if we roll that back, we have similar failures for virtio-blk, and most
> likely the other virtio devices touched by the refactoring.
>
> The issue seems to be a change the way section id strings are generated in
> vmstate_register(). In v1.4.x we had:
>
> se->instance_id: 0, se->idstr: 0000:00:03.0/virtio-net
>
> In v1.5.0-rc2 we have:
>
> se->instance_id: 0, se->idstr: virtio-net
>
> This seems to be due to the fact that these devices now sit on a
> TYPE_VIRTIO_BUS that has no implementation of TYPE_BUS's get_dev_path()
> interface, which is what savevm uses to calculate the id prefix for
> se->idstr.
>
> Prior to the refactoring, the device sat on a TYPE_PCI_BUS which used
> pcibus_get_dev_path() to calculate this.
>
> I'm not sure what the best fix is for this. I looking at implementing
> get_dev_path() for TYPE_VIRTIO_BUS, but to maintain migration
> compatibility we'd end up baking in PCI-specific stuff which from what
> I gather is exactly what we were trying to avoid there.
>
> I think adding a compat string property to TYPE_VIRTIO_DEVICE and having
> that get set somewhere like virtio_bus_plug_device() is a better
> approach, but vmstate_register() gets call during TYPE_VIRTIO_DEVICE
> init which I think happens before then.
>
> Still looking at it but if someone more familiar with this code has
> some ideas or wants to whip up a patch please jump right in.

Sorry for that.
Have you made progress?

I'm trying to add get_dev_path function to virtio-pci-bus in 
virtio-pci.c as Paolo suggests.

How do you get those instance_id to check It's working?

Fred
>> Regards,
>>
>> Anthony Liguori
>>
>>