I get this error now. At least its something different!
LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/ QEMU_AUDIO_DRV=none /usr/local/sbin/qemu -name 'guest=Windows 10,debug-threads=on' -S -object 'secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-2-Windows 10/master-key.aes' -machine pc-q35-3.0,accel=kvm,usb=off,dump-guest-core=off,mem-merge=off -cpu host,hv_time,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff,hv_vendor_id=none -m 8192 -realtime mlock=off -smp 4,sockets=1,cores=2,threads=2 -uuid d80d161a-ad22-ae0a-c7bd-a03fb0e37e7c -display none -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=25,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime -no-hpet -no-shutdown -boot strict=on -device pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x1 -device pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 -device pcie-root-port,port=0xa,chassis=3,id=pci.3,bus=pcie.0,addr=0x1.0x2 -device pcie-root-port,port=0xb,chassis=4,id=pci.4,b.0 -device vfio-pci,host=02:00.0,id=hostdev0,x-vga=on,bus=pci.4,addr=0x0 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny -msg timestamp=on
2019-03-12 04:32:10.889+0000: Domain id=2 is tainted: high-privileges
2019-03-12 04:32:10.889+0000: Domain id=2 is tainted: host-cpu
2019-03-12T04:32:10.920502Z qemu-system-x86_64: -chardev pty,id=charserial0: char device redirected to /dev/pts/0 (label charserial0)
2019-03-12T04:32:12.092333Z qemu-system-x86_64: vfio: Cannot reset device 0000:02:00.0, depends on group 19 which is not owned.
2019-03-12T04:32:12.097306Z qemu-system-x86_64: vfio: Cannot reset device 0000:02:00.0, depends on group 19 which is not owned.