Bug 807508

Summary: Hotplug vcpu fail during guest booting.
Product: Red Hat Enterprise Linux 6 Reporter: FuXiangChun <xfu>
Component: qemu-kvmAssignee: Igor Mammedov <imammedo>
Status: CLOSED NOTABUG QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.3CC: acathrow, areis, bsarathy, chayang, dyasny, flang, juzhang, michen, mkenneth, qzhang, shu, sluo, virt-maint, wdai, xuzhang
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2012-03-29 08:58:10 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description FuXiangChun 2012-03-28 02:25:28 UTC 
Description of problem:
after guest boot. use 'top' and 'cat /proc/cpuinfo' cann't get vcpu but 'ls
/sys/device/system/cpus/' can see added vcpu in guest

Version-Release number of selected component (if applicable):
host kernel:
# uname -r
2.6.32-257.el6.x86_64

qemu vesion:
qemu-kvm-0.12.1.2-2.265.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1./usr/libexec/qemu-kvm -M rhel6.3.0 -cpu host --enable-kvm -m 4G -smp
1,maxcpus=161 -name rhel6.3 -uuid ddcbfb49-3411-1701-3c36-6bdbc00bedbb -rtc
base=utc,clock=host,driftfix=slew -drive
file=/dev/vg-54/lvtest,if=none,id=ide,format=qcow2,cache=none,werror=stop,rerror=stop
-device ide-drive,drive=ide,id=drive-ide0-0-0,bootindex=1 -netdev
tap,id=hostnet1 -device e1000,netdev=hostnet1,id=net1,mac=86:12:50:a4:32:72
-spice port=5911,disable-ticketing -vga qxl -device sga -chardev
socket,id=serial0,path=/var/test1,server,nowait -device
isa-serial,chardev=serial0 -balloon virtio -monitor
unix:/tmp/monitor2,server,nowait -monitor stdio

2.hotplug vcpus during booting. 
cpu_set 1 online
cpu_set 2 online
3.
  
Actual results:
hotplug fail

Expected results:
hotplug successfully and guest work well

Additional info:
Comment 2 Igor Mammedov 2012-03-29 08:58:10 UTC 
cpus are onlined by udev, so you have to have a fully booted guest for hot-plugged cpu to be onlined and visible in /proc/cpuinfo