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Bug 1094285 - Hot plug CPU not working with RHEL6 machine types running on RHEL7 host.
Summary: Hot plug CPU not working with RHEL6 machine types running on RHEL7 host.
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm
Version: 7.0
Hardware: x86_64
OS: Linux
unspecified
high
Target Milestone: rc
: ---
Assignee: Paolo Bonzini
QA Contact: Virtualization Bugs
URL:
Whiteboard: virt
Depends On:
Blocks: RHEL7.0Virt-PostBeta(0-Day) 1093411 1094820
TreeView+ depends on / blocked
 
Reported: 2014-05-05 12:21 UTC by Karen Noel
Modified: 2015-03-05 08:06 UTC (History)
23 users (show)

Fixed In Version: qemu-kvm-1.5.3-62.el7
Doc Type: Bug Fix
Doc Text:
Previously, an internal error prevented KVM from executing a CPU hot plug on a Red Hat Enterprise Linux 7 guest running on a Red Hat Enterprise Linux 7 host. This update addresses the internal error and CPU hot plugging in the described scenario now functions correctly.
Clone Of: 1093411
Environment:
Last Closed: 2015-03-05 08:06:47 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
[RHEL-7.0 qemu-kvm PATCH] pc: enable CPU hotplug for RHEL6.{45}u PIIX machines and disable it for Q35 (1.89 KB, patch)
2014-05-06 07:45 UTC, Igor Mammedov 		no flags Details | Diff
Show Obsolete (1) View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2015:0349 0 normal SHIPPED_LIVE Important: qemu-kvm security, bug fix, and enhancement update 2015-03-05 12:27:34 UTC

Comment 1 Paolo Bonzini 2014-05-05 13:48:34 UTC 
I can take care of this, the fix is trivial.
Comment 3 FuXiangChun 2014-05-06 02:07:01 UTC 
Reproduced this issue with qemu-kvm-rhev-1.5.3-60.el7ev.x86_64.

steps:
1.Boot qemu-kvm process as following command line
/usr/libexec/qemu-kvm -M rhel6.x.x -m 8G -smp 4,sockets=2,cores=2,thread=1,maxcpus=160 .......

2. check vcpu number 
(qemu) info cpus
* CPU #0: pc=0x00000000000fe7e0 thread_id=32603
  CPU #1: pc=0x00000000000f6277 (halted) thread_id=32604
  CPU #2: pc=0x00000000000f6277 (halted) thread_id=32605
  CPU #3: pc=0x00000000000f6277 (halted) thread_id=32606

3. hotplug vcpu via qmp command
{ "execute": "cpu-add", "arguments": { "id": 4 }}

result:
{"error": {"class": "GenericError", "desc": "Not supported"}}

4. re-check vcpu number
(qemu) info cpus
* CPU #0: pc=0x00000000000fe7e0 thread_id=32603
  CPU #1: pc=0x00000000000f6277 (halted) thread_id=32604
  CPU #2: pc=0x00000000000f6277 (halted) thread_id=32605
  CPU #3: pc=0x00000000000f6277 (halted) thread_id=32606

Notes:
QE tested -M rhel6.0.0 ~ rhel6.5.0. All machine type rhel6.x.x don't work.
Comment 4 Igor Mammedov 2014-05-06 07:45:17 UTC 
Created attachment 892795 [details]
[RHEL-7.0 qemu-kvm PATCH] pc: enable CPU hotplug for RHEL6.{45}u PIIX machines and disable it for Q35
Comment 5 Igor Mammedov 2014-05-06 11:37:26 UTC 
Comment on attachment 892795 [details]
[RHEL-7.0 qemu-kvm PATCH] pc: enable CPU hotplug for RHEL6.{45}u PIIX machines and disable it for Q35

it was a wrong patch.
Comment 9 langfang 2014-11-28 03:11:40 UTC 
Reproduce this bug as follow version:
Host:
# uname -r
3.10.0-210.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-1.5.3-60.el7ev.x86_64


guest:
win2012r2

Steps:
1.Boot guest with "-M rhel6.5.0"
...-smp 2,maxcpus=8...

2.Hotadd vcpu
{ "execute": "cpu-add", "arguments": { "id":2 }}
{"error": {"class": "GenericError", "desc": "Not supported"}}

Results: Not support

Verify this bug as follow version:

Version:
# uname -r
3.10.0-210.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-1.5.3-82.el7ev.x86_64

Guest:wini2012r2

Steps 
1.Boot guest with "-M rhel6.5.0"
...-M rhel6.5.0...-smp 2,maxcpus=8...

2.Hotadd vcpu
{ "execute": "cpu-add", "arguments": { "id":2 }}
{ "execute": "cpu-add", "arguments": { "id":3 }}


3.Tried the same steps for "-M rhel6.4.0/rhel6.3.0/rhel6.2.0/rhel6.1.0/rhel6.0.0/pc-i440fx-rhel7.0.0

Results:
...
{ "execute": "cpu-add", "arguments": { "id":2 }}
{"return": {}}
{ "execute": "cpu-add", "arguments": { "id":3 }}
{"return": {}}


In guest: can be see the new add vcpu

Addtinonal info:
1.Also tried rhel6 guest,work well
2.Tried on AMD machine,work well


According to above test ,this bug has been fixed.
Comment 12 errata-xmlrpc 2015-03-05 08:06:47 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2015-0349.html
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