Bug 1461686

Description of problem:
Failed to boot up guest with "-cpu POWER9"  on power9 host

Version-Release number of selected component (if applicable):
host kernel:4.11.0-7.el7.test.ppc64le
guest kernel:4.11.0-5.el7.ppc64le
qemu-kvm-rhev-2.9.0-7.el7.ppc64le
host cpu model:
[root@localhost test]# lscpu
Architecture:          ppc64le
Byte Order:            Little Endian
CPU(s):                16
On-line CPU(s) list:   0-15
Thread(s) per core:    4
Core(s) per socket:    2
Socket(s):             2
NUMA node(s):          2
Model:                 1.0 (pvr 004e 0100)
Model name:            POWER9 (raw), altivec supported
L1d cache:             32K
L1i cache:             32K
L2 cache:              512K
L3 cache:              10240K
NUMA node0 CPU(s):     0-7
NUMA node8 CPU(s):     8-15


How reproducible:
100%

Steps to Reproduce:
1.Boot up gues with command:
/usr/libexec/qemu-kvm \
 -name vm \
 -m 8192 \
 -rtc base=utc,clock=vm \
 -chardev stdio,mux=on,id=serial_id_serial0,server,nowait \
 -M pseries -cpu POWER9\
 -device spapr-vty,id=serial111,chardev=serial_id_serial0 \
 -mon chardev=serial_id_serial0,mode=readline \
 -nodefaults \
 -smp 4,maxcpus=4,cores=4,threads=1,sockets=1 \
 -device virtio-scsi-pci,bus=pci.0,addr=0x5 \
 -device scsi-hd,id=scsi-hd0,drive=scsi-hd-dr0,bootindex=1\
 -drive file=pegas.qcow2,if=none,id=scsi-hd-dr0,format=qcow2,cache=none \
 -device virtio-net-pci,netdev=net0,id=nic0,mac=70:e2:84:14:e7:84 \
 -netdev tap,id=net0,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown,vhost=on 
2.
3.

Actual results:
Failed to boot up guest with error:
qemu-kvm: Unable to find sPAPR CPU Core definition
device tap0 is not a slave of switch
qemu-kvm: network script /etc/qemu-ifdown failed with status 256


Expected results:
Boot up without error.


Additional info:
ppc only