Description of problem:
Failed to create a live snapshot for the disk with io throttling parameters.

Version-Release number of selected component (if applicable):
Host:
RHEL-8.0-20181118.n.0
kernel-4.18.0-40.el8.x86_64
qemu-kvm-3.0.0-2.module+el8+2208+e41b12e0.x86_64
     
Guest:
RHEL-8.0-20181101.1
kernel-4.18.0-45.el8.x86_64


How reproducible:
100%

Steps to Reproduce:
1) Boot the guest with below command line:
/usr/libexec/qemu-kvm -M q35 \
-S \
-cpu SandyBridge \
-enable-kvm \
-m 4G \
-smp 4 \
-object iothread,id=iothread0 \
-object throttle-group,id=foo,x-bps-total=512000,x-bps-total-max=5120000,x-iops-total=100,x-bps-total-max-length=4 \
-rtc base=utc,clock=host,driftfix=slew \
-device pcie-root-port,id=pcie.0-root-port-2,slot=2,chassis=2,addr=0x2,bus=pcie.0 \
-device pcie-root-port,id=pcie.0-root-port-3,slot=3,chassis=3,addr=0x3,bus=pcie.0 \
-device virtio-scsi-pci,id=scsi0,iothread=iothread0,bus=pcie.0-root-port-2,addr=0x0 \
-blockdev driver=raw,cache.direct=off,cache.no-flush=on,file.filename=/home/kvmtest/win2.raw,node-name=win_disk,file.driver=file \
-device scsi-hd,drive=win_disk \
-blockdev driver=throttle,throttle-group=foo,cache.direct=off,cache.no-flush=on,file.filename=/home/kvmtest/data2.raw,node-name=data_disk,file.driver=file \
-device scsi-hd,drive=data_disk,id=data \
-device virtio-net-pci,mac=3c:0b:65:a6:90:66,id=netdev1,vectors=4,netdev=net1,bus=pcie.0-root-port-3 -netdev tap,id=net1,vhost=on \
-qmp tcp:0:4446,server,nowait \
-vga qxl \
-vnc :4 \
-monitor stdio \
-boot menu=on \

2) Create a snapshot image in previous:
{'execute':'blockdev-create','arguments':{'options': {'driver':'file','filename':'/home/kvmtest/1.raw','size':21474836480},'job-id':'job1'}}
{'execute':'blockdev-add','arguments':{'driver':'file','node-name':'data_disk1','filename':'/home/kvmtest/1.raw'}}
{'execute':'job-dismiss','arguments':{'id':'job1'}}

3) Do live snapshot;
{ "execute": "transaction", "arguments": { "actions":[{ 'type': 'blockdev-snapshot', 'data' : { "node": "data_disk","overlay":"data_disk1"}}]}}


Actual results:
For step3, {"error": {"class": "GenericError", "desc": "The feature 'snapshot' is not enabled"}}

Expected results:
Could create the snapshot successfully.


Additional info:
1) cpu info of the host:
]# lscpu
Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              24
On-line CPU(s) list: 0-23
Thread(s) per core:  2
Core(s) per socket:  6
Socket(s):           2
NUMA node(s):        2
Vendor ID:           GenuineIntel
CPU family:          6
Model:               45
Model name:          Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
Stepping:            7
CPU MHz:             2499.851
CPU max MHz:         2500.0000
CPU min MHz:         1200.0000
BogoMIPS:            3999.76
Virtualization:      VT-x
L1d cache:           32K
L1i cache:           32K
L2 cache:            256K
L3 cache:            15360K
NUMA node0 CPU(s):   0-5,12-17
NUMA node1 CPU(s):   6-11,18-23
Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid xsaveopt dtherm ida arat pln pts flush_l1d