Re: [Qemu-devel] q35 migration broken

[Marcel Apfelbaum <marcel@redhat.com>]

On 04/01/2016 06:54 PM, Dr. David Alan Gilbert wrote:
> * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote:
>> * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote:
>>> Hi,
>>>    I'm seeing a breakage on q35 migration on head (and possibly older
>>> but certainly head; it's also on a 2.5.0 world I've got with a bunch
>>> of patches but I've not tried a clean 2.5.0 yet).
>>>
>>> It looks like some type of interrupt screwup; with a virtio-net device
>>> I get a:
>>>    BUG: soft lockup - CPU#0 stuck for 22s!
>>>    ...  virtnet_config_changed_work
>>>
>>> but if I swap that out for an e1000 I get:
>>>    Disabling IRQ #22
>>>
>>>    and various timeouts on e1000 and cdrom (scsi).
>>> The guest kind of limps along with an existing terminal scrolling dmesg -w output.
>>>
>>> This is an f23 guest on a rhel7.2-ish host; with the guest sitting an idle
>>> (MATE) Gui.
>>
>> Also broken with 2.4.1 and 2.5.1 (with pc-q35-2.4 machine type);
>> see a screen shot attached; note:
>>     a) The large count on irq 22 (enp2s1) on cpu1
>>     b) The large count on virtio2-config on cpu1
>>     c) The count of 'Deferred Error APIC interrupts'.
>
> OK, this seems to be the i82801b11-bridge; if I remove it from the config
> it all works.
>
> My minimum config that fails so far is:
> /opt/qemu-head/bin/qemu-system-x86_64 -nographic -machine pc-q35-2.6,accel=kvm,usb=off,vmport=off -cpu SandyBridge -m 4096 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 \
>   -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
>   -drive id=image,file=/home/vms/f23-serial.qcow2,if=none,cache=none \
>   -device virtio-blk-pci,scsi=off,bus=pci.1,addr=0x5,drive=image,id=virtio-disk0,bootindex=1 \
>   $*
>
> if I flip the i82801b11-bridge for a pci-bridge  then it works.

Hi Dave,
That's good news. I see we don't have a vmstate for this bridge, but we do have one for the regular pci-bridge.
Maybe this is the problem?

Thanks,
Marcel

>
> Dave
>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>