virtio-serial-bus: Unexpected port id

With qemu-kvm-0.15.0-rc1 virtio-serial-bus reports an error, and windows vdagent can not start.  qemu-0.15.0-rc1 behaves as expected, ie vdagent runs in the guest, mouse passes seamlessly between spicec and host and copy/paste works between guest and host.
qemu-kvm has been configured with
./configure --target-list=x86_64-softmmu --disable-curses  --disable-curl --audio-drv-list=alsa --audio-card-list=sb16,ac97,hda --enable-vnc-thread --disable-bluez --enable-vhost-net --enable-spice
and is started with
qemu-system-x86_64 -cpu host -enable-kvm -pidfile /home/rick/qemu/hds/wxp.pid -drive file=/home/rick/qemu/hds/wxp.raw,if=virtio,aio=native -m 1536 -name WinXP -net nic,model -net user -localtime -usb -vga qxl -device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0,addr=0x5 -chardev spicevmc,name=vdagent,id=vdagent -device virtserialport,nr=1,bus=virtio-serial0.0,chardev=vdagent,name=com.redhat.spice.0 -spice port=1234,disable-ticketing -monitor stdio

I've also tried start qemu like
qemu-system-x86_64 -cpu host -enable-kvm -pidfile /home/rick/qemu/hds/wxp.pid -drive file=/home/rick/qemu/hds/wxp.raw,if=virtio -m 768 -name WinXP -net nic,model=virtio -net user -localtime -usb -vga qxl -device virtio-serial -chardev spicevmc,name=vdagent,id=vdagent -device virtserialport,chardev=vdagent,name=com.redhat.spice.0 -spice port=1234,disable-ticketing -monitor stdio
and observed the same results.

the host runs 2.6.39.4 vanilla kernel.  the guest uses the most recent virtio-serial, vga-qxl and vdagent from spice-space.org

sorry, the output from qemu-kvm which seems to indicate an error is
qemu-system-x86_64: virtio-serial-bus: Unexpected port id 3125770964 for device virtio-serial0.0
or sometimes
qemu-system-x86_64: virtio-serial-bus: Unexpected port id 47936 for device virtio-serial0.0

This continues to occur with qemu-kvm 0.15 on only one of my WXP VMs.  The fact that one of them works fine led me to believe it was a windows issue (or spice), but the fact that both work fine with straight qemu indicates that there is something with qemu-kvm involved in the problem.

Using qemu-kvm-0.15.0 for a few weeks now, I'd like to report that maybe 1/10 times it works as expected: ie, there is no virtio-serial-bus error, vdagent in the windows guest starts, etc.

I can confirm this Bug with qemu 1.0 using a Windows7 or Windows 2003 virtual machine.
After connecting 1-10 times the agent stops working.
Sometimes it helps to restart the VD Service within the vm.
Qemu  Log shows:
dispatch_vdi_port_data: invalid port



I met two bugs above.QEMU version is 2.1.3 and VM is Windows7.
QEMU Log is:
qemu-system-x86_64: virtio-serial-bus: Unexpected port id 15819934 for device virtio-serial0.0

Triaging old bug tickets ... Can you still reproduce this problem with the latest version of QEMU?

[Expired for QEMU because there has been no activity for 60 days.]

This looks like https://bugzilla.redhat.com/show_bug.cgi?id=819412  which is about the same age.