Re: [Qemu-devel] q35 migration broken

[Dr. David Alan Gilbert]

* Dr. David Alan Gilbert (address@hidden) wrote:
> * Dr. David Alan Gilbert (address@hidden) 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.

Dave

--
Dr. David Alan Gilbert / address@hidden / Manchester, UK