Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

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:
Embargoed:

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