Bug 656984

Summary: TSC offset of virtual machines is not initialized correctly by 'kvm_amd' kernel module.
Product: Red Hat Enterprise Linux 5 Reporter: RHEL Program Management <pm-rhel>
Component: kvmAssignee: Virtualization Maintenance <virt-maint>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: high Docs Contact:
Priority: high    
Version: 5.6CC: akong, ehabkost, gcosta, juzhang, michen, mjenner, mkenneth, plyons, pm-eus, tburke, uobergfe, virt-maint, ykaul, zamsden
Target Milestone: rcKeywords: ZStream
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: kvm-83-164.el5_5.30 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2010-12-20 17:37:20 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:
Bug Depends On: 642659    
Bug Blocks: 580949    

Description RHEL Program Management 2010-11-24 16:08:58 UTC
This bug has been copied from bug #642659 and has been proposed
to be backported to 5.5 z-stream (EUS).

Comment 7 juzhang 2010-12-15 02:07:38 UTC
Using the bz642659 comment26 test on kvm-83-164.el5_5.29,failed.

---snip of output---
crash> px ((struct vcpu_svm *)0xffff810133e841c0)->vcpu.arch.host_tsc
$9 = 0x1322fe6d16801

crash> px ((struct vcpu_svm *)0xffff810133e841c0)->vmcb.control.tsc_offset
$8 = 0xfffd9ba044aaf031

crash> px 0-0xfffd9ba044aaf031
$10 = 0x2645fbb550fcf

crash> pd 0x1322fe6d16801-0x2645fbb550fcf
$11 = -336655986960334
             -----The difference between host TSC and guest TSC offset is
-336655986960334(negative) cycles,so,failed.

Set this issue status as assigned.

Comment 8 Zachary Amsden 2010-12-15 04:48:07 UTC
Fixes have not been ported to 5.5.z yet, so failure is expected.

Comment 9 Dor Laor 2010-12-15 08:06:11 UTC
(In reply to comment #8)
> Fixes have not been ported to 5.5.z yet, so failure is expected.

Which fixes Zach? comment #4 states that the fixes are there. Are there more?

Comment 12 Zachary Amsden 2010-12-15 15:26:31 UTC
(In reply to comment #9)
> (In reply to comment #8)
> > Fixes have not been ported to 5.5.z yet, so failure is expected.
> 
> Which fixes Zach? comment #4 states that the fixes are there. Are there more?

I checked the 5.5.z git tree and no changes had been ported.  I haven't worked with z-stream before so I'm not 100% familiar with the process.

Now I can't access git at all.

[zamsden@mysore rhel5.5.z]$ git pull
fatal: The remote end hung up unexpectedly

On second thought, perhaps I'm a bit confused.  The changes would be to the KVM module, which isn't part of the 5.5.z git tree.  In fact, I don't know where the KVM tree corresponding to 5.5.z lives.  Is there a kvm-rhel5.5.z.git tree to which these should be ported?

Also, there were two patches, the first required a correction.  Perhaps one of them is missing.

I'll check as soon as git access is restored.

Comment 13 Zachary Amsden 2010-12-15 15:45:00 UTC
Okay, it looks as though the kvm-rhel5.5.z kmod is built from the branch rhel55/next in the kvm-rhel5 git tree, and that Eduardo just pulled the second fix into that branch.  All should be well now.

Comment 14 juzhang 2010-12-16 03:09:16 UTC
Verified on kvm-83-164.el5_5.30,passed.

---snip of output---

crash> px ((struct vcpu_svm *)0xffff81011e19c040)->vcpu.arch.host_tsc
$6 = 0x1ef3ea5660f29
crash> px ((struct vcpu_svm *)0xffff81011e19c040)->vmcb.control.tsc_offset
$7 = 0xfffe10c16374676f
crash> px 0-0xfffe10c16374676f
$8 = 0x1ef3e9c8b9891
crash> pd 0x1ef3ea5660f29-0x1ef3e9c8b9891
$9 = 148534936

The difference between host TSC and guest TSC offset
              is only 148534936 cycles.

Comment 17 errata-xmlrpc 2010-12-20 17:37:20 UTC
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2010-0998.html