PowerPC guest does not emulate L2 and L3 cache for KVM vCPUs

PowerPC KVM guest does not emulate L2 and L2 caches for vCPU, it would be good to have them enabled if not any known issues/limitation already with PowerPC.

Host Env:
kernel: 4.17.0-rc7-00045-g0512e0134582
qemu: v2.12.0-923-gc181ddaa17-dirty
#libvirtd -V
libvirtd (libvirt) 4.4.0


Guest Kernel:
# uname -a
Linux atest-guest 4.17.0-rc7-00045-g0512e0134582 #9 SMP Fri Jun 1 02:55:50 EDT 2018 ppc64le ppc64le ppc64le GNU/Linux

Guest:
# lscpu
Architecture:        ppc64le
Byte Order:          Little Endian
CPU(s):              16
On-line CPU(s) list: 0-15
Thread(s) per core:  8
Core(s) per socket:  2
Socket(s):           1
NUMA node(s):        1
Model:               2.1 (pvr 004b 0201)
Model name:          POWER8 (architected), altivec supported
Hypervisor vendor:   KVM
Virtualization type: para
L1d cache:           64K
L1i cache:           32K
NUMA node0 CPU(s):   0-15



background: x86 enabling cpu L2 cache bydefault and L3 cache on demand for kvm guest
and claims performance improvement as vcpus can be 
benefited with lesser `vmexits due to guest send IPIs.` with L3 cache enabled, below was patch for same.

https://git.qemu.org/?p=qemu.git;a=commit;h=14c985cffa6cb177fc01a163d8bcf227c104718c