[Pkg-libvirt-maintainers] Bug#863266: Bug#863266: libvirt-daemon: spice port conflict - multiple VMs want Port 5900

[bob-debian-bugtracker]

This appears to be related to kernel changes? At least on my end.
 
I have no issues starting multiple VMs while running 4.9.0-3 on Stretch.
 
However, I get the Spice error on 4.11.0-1, installed from Buster on top of a mostly-Stretch system.

It works again after downgrading the kernel, and breaks again after upgrading.

Changing the port allows the VM to start, so probably the same issue.

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Working:

4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26)
 
Broken:

4.11.0-1-amd64 #1 SMP Debian 4.11.6-1 (2017-06-19)

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error: internal error: process exited while connecting to monitor: annel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -device usb-tablet,id=input0,bus=usb.0,port=1 -spice port=5900,addr=127.0.0.1,disable-ticketing,seamless-migration=on -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pci.0,addr=0x2 -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -chardev spicevmc,id=charredir0,name=usbredir -device usb-redir,chardev=charredir0,id=redir0,bus=usb.0,port=2 -chardev spicevmc,id=charredir1,name=usbredir -device usb-redir,chardev=charredir1,id=redir1,bus=usb.0,port=3 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8 -msg timestamp=on
Domain id=5 is tainted: host-cpu
((null):4168): Spice-Warning **: reds.c:2530:reds_init_socket: listen: Address already in use
2017-08-03T04:27:44.895321Z qemu-system-x86_64: failed to initialize spice server

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Incidentally, I upgraded the kernel to test nested Hyper-V within KVM, which requires 4.10 at a minimum[1]. Backports were not suitable since the updated zfs-dkms package is not available in stretch-backports, but the backports kernel is 4.11.0-0 anyway.
  
[1]: https://ladipro.wordpress.com/2017/07/21/hyperv-in-kvm-known-issues/

-- 
Bob