[vfio-users] libvirt-3.0.0 from libvirt-2.4.0 breaks Windows VMs

[Anthony M de Beus]

Haven't seen mention of this elsewhere yet, not sure if this is the best
place to post it.

I just updated to libvirt-3.0.0-1 on Arch from libvirt-2.4.0-2 and my
Windows VMs no longer start. Reverting to libvirt-2.4.0-2 reverses the
problem.  The problem affects Windows 7 and XP, the XP machine doesn't
have GPU passthrough.  A CAELinux VM still runs.  journalctl shows,
under libvirtd 3.0.0

Jan 26 06:46:35 bozo systemd[1]: Started Virtual Machine qemu-1-Windows7.
Jan 26 06:46:35 bozo virtlogd[30871]: 2017-01-26 13:46:35.878+0000:
30871: info : libvirt version: 3.0.0
Jan 26 06:46:35 bozo virtlogd[30871]: 2017-01-26 13:46:35.878+0000:
30871: info : hostname: bozo
Jan 26 06:46:35 bozo virtlogd[30871]: 2017-01-26 13:46:35.878+0000:
30871: error : virNetSocketReadWire:1800 : End of file while reading
data: Input/output error
Jan 26 06:46:35 bozo virtlogd[30871]: 2017-01-26 13:46:35.880+0000:
30871: error : virNetSocketReadWire:1800 : End of file while reading
data: Input/output error

/var/log/libvirt/qemu/Windows7.log shows

2017-01-26 13:46:35.702+0000: starting up libvirt version: 3.0.0, qemu
version: 2.8.0, hostname: bozo
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
QEMU_AUDIO_DRV=spice /usr/sbin/qemu-system-x86_64 -name
guest=Windows7,debug-threads=on -S -object
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-Wind$
Domain id=1 is tainted: cdrom-passthrough
libvirt:  error : libvirtd quit during handshake: Input/output error
2017-01-26 13:46:35.878+0000: shutting down, reason=failed


Whereas under 2.4.0, journalctl shows

bozo systemd[1]: Started Virtual Machine qemu-3-Windows7.
Jan 26 10:28:07 bozo kernel: qemu-system-x86: sending ioctl 5326 to a
partition!
Jan 26 10:28:07 bozo dhcpcd[708]: vnet0: soliciting a DHCP lease
......bunch of normal vm assignments....
Jan 26 10:28:11 bozo kernel: usb 4-1.8.4: reset high-speed USB device
number 8 using ehci-pci
Jan 26 10:28:11 bozo virtlogd[1512]: End of file while reading data:
Input/output error
Jan 26 10:28:12 bozo kernel: kvm: zapping shadow pages for mmio
generation wraparound
Jan 26 10:28:12 bozo kernel: kvm: zapping shadow pages for mmio
generation wraparound
Jan 26 10:28:14 bozo kernel: usb 4-1.2: reset low-speed USB device
number 4 using ehci-pci
...bunch of normal vm assignments and synergy messages....
017-01-26T10:29:33] NOTE: client "penguin" has connected
Jan 26 10:29:33 bozo synergys[1189]:        
/build/synergy/src/synergy-1.8.7-stable/src/lib/server/Server.cpp,337
Jan 26 10:31:56 bozo synergys[1189]: [2017-01-26T10:31:56] NOTE: client
"penguin" has disconnected
Jan 26 10:31:56 bozo synergys[1189]:        
/build/synergy/src/synergy-1.8.7-stable/src/lib/server/ClientProxy1_0.cpp,213

and /var/log/libvirt/qemu/Windows7.log shows

2017-01-24 17:34:33.446+0000: starting up libvirt version: 2.4.0, qemu
version: 2.8.0, hostname: bozo
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
QEMU_AUDIO_DRV=spice /usr/sbin/qemu-system-x86_64 -name
guest=Windows7,debug-threads=on -S -object
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-Wind$
Domain id=1 is tainted: cdrom-passthrough
2017-01-24T21:08:41.957097Z qemu-system-x86_64: terminating on signal 15
from pid 889 (/usr/bin/libvirtd)
2017-01-24 21:08:43.686+0000: shutting down, reason=shutdown


In summary, looks like a handshake error with the network in
virNetSocketReadWire.  I found this
https://www.redhat.com/archives/libvir-list/2016-October/msg00745.html,
implementing a new libssh transport.

Suggestions? Places to post this error other than here? I realize this
isn't probably a vfio related bug.