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Bug 1320066 - Qemu should not report error when cmdline set threads=2 in Intel host
Summary: Qemu should not report error when cmdline set threads=2 in Intel host
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: qemu-kvm
Version: 6.8
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Wei Huang (AMD)
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks: 1359965
TreeView+ depends on / blocked
 
Reported: 2016-03-22 09:15 UTC by weliao
Modified: 2017-03-21 09:37 UTC (History)
13 users (show)

Fixed In Version: qemu-kvm-0.12.1.2-2.495.el6
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-03-21 09:37:24 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
patch (2.79 KB, patch)
2016-03-25 07:02 UTC, Wei Huang (AMD) 		no flags Details | Diff
View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2017:0621 0 normal SHIPPED_LIVE Moderate: qemu-kvm security and bug fix update 2017-03-21 12:28:31 UTC

Description weliao 2016-03-22 09:15:43 UTC 
Description of problem:
In Intel host, when qemu cmdline set threads=2, without -cpu specified, report 
qemu-kvm: AMD CPU doesn't support hyperthreading. Please configure -smp options properly.

Version-Release number of selected component (if applicable):
2.6.32-633.el6.x86_64
qemu-kvm-0.12.1.2-2.490.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.# /usr/libexec/qemu-kvm -name win10 -m 6G -smp 2,threads=2,cores=1,sockets=1
qemu-kvm: AMD CPU doesn't support hyperthreading. Please configure -smp options properly.
VNC server running on `::1:5900'
2.
3.

Actual results:
report error:
qemu-kvm: AMD CPU doesn't support hyperthreading. Please configure -smp options properly.

Expected results:
should not report this error

Additional info:
My machine:
model name	: Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz
just  happens without -cpu specified,  if -cpu type is AMD, report this error, -cpu type is Intel ,didn't report

retest qemu-kvm-0.12.1.2-2.483.el6.x86_64, no this issue,so this a Regression
Comment 2 weliao 2016-03-22 09:27:08 UTC 
Hi,Wei
  Seems this bug because fixed Bug 1292678 - Qemu should report error when cmdline set threads=2 in amd host , Can you check it? and on rhel7.2 no this issue.

thanks 
Wei
Comment 4 Wei Huang (AMD) 2016-03-22 20:48:13 UTC 
I can reproduce this bug on Intel box. However I think this isn't a bug from the instrumentation I did with QEMU 6.8. Here are the findings:

1) The problem was introduced by commit 50d095912. The related code is in 
   pc_new_cpu() of hw/pc.c file.
2) IS_INTEL_CPU(env) is TRUE, implying that QEMU believes guest is an AMD CPU.
3) I instrumented cpu_x86_register() of target-i386/cpuid.c file. When no -cpu
   is specified, cpu_model name is "cpu64-rhel6". So by default qemu-kvm-6.8 uses
   "cpu64-rhel6" as the CPU model when nothing is specified. According to
   target-i386/cpuid.c, "cpu64-rhel6" is based on AMD CPU model.

From the data collected above, I think this warning msg is legit because AMD CPU doesn't support HyperThreading.

-Wei
Comment 5 Wei Huang (AMD) 2016-03-24 14:09:48 UTC 
Is it a common usage case not to specify "-cpu"? I am trying to understand how annoying this warning message is.
Comment 6 juzhang 2016-03-25 00:15:39 UTC 
(In reply to Wei Huang from comment #5)
> Is it a common usage case not to specify "-cpu"? I am trying to understand
> how annoying this warning message is.

Hi Wei,

I personally think it's no common scenario. However, 2 concerns.

1. Seems this is regression issue according to comment0

2. It's strange that the qemu-kvm promotes message like "AMD CPU doesn't support ..." but the qemu runs on Intel host.

Best Regards,
Junyi
Comment 7 Wei Huang (AMD) 2016-03-25 07:02:35 UTC 
Created attachment 1140266 [details]
patch
Comment 8 Wei Huang (AMD) 2016-03-25 07:03:46 UTC 
This issue is indeed a regression. I have created a patch to fix the problem.
Comment 11 Yash Mankad 2016-10-27 20:33:13 UTC 
Fix included in qemu-kvm-0.12.1.2-2.495.el6
Comment 13 Yiqian Wei 2016-10-28 02:23:03 UTC 
Reproduce proceduce
Host version:
    kernel-2.6.32-642.el6.x86_64
    qemu-kvm-0.12.1.2-2.490.el6.x86_64 
Steps to Reproduce:
1./usr/libexec/qemu-kvm -name win10 -m 6G -smp 2,threads=2,cores=1,sockets=1
qemu-kvm: AMD CPU doesn't support hyperthreading. Please configure -smp options properly.
VNC server running on `::1:5900'
 
Actual results:
report error:
qemu-kvm: AMD CPU doesn't support hyperthreading. Please configure -smp options properly.

-------------------------------------------
Verify this bug 
Host version:
     kernel-2.6.32-642.el6.x86_64
     qemu-kvm-0.12.1.2-2.495.el6.x86_64
Test steps:
1./usr/libexec/qemu-kvm -name win10 -m 6G -smp 2,threads=2,cores=1,sockets=1
VNC server running on `::1:5900'

Test results:
  not report this error.
Conclusion：
  According to result above,this bug has been fixed.

Additional info:
My machine:
model name	: Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
Comment 16 errata-xmlrpc 2017-03-21 09:37:24 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-2017-0621.html
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