Bug 592021

Summary:	race condition in pvclock wallclock calculation
Product:	Red Hat Enterprise Linux 5	Reporter:	Glauber Costa <gcosta>
Component:	kvm	Assignee:	Glauber Costa <gcosta>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	5.5	CC:	bcao, jwest, mjenner, tburke, virt-maint, ykaul
Target Milestone:	rc	Keywords:	ZStream
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kvm-83-182.el5	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:
Clones:	592033 (view as bug list)		Environment:
Last Closed:	2011-01-13 23:35:32 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:
Bug Blocks:	580948, 592033, 596623, 596625

Description Glauber Costa 2010-05-13 17:31:33 UTC

The hypervisor code for wallclock setting in pvclock is subject to race, since the version variable is static, and thus, shared among all guests.

This means that theoretically, one guest can mess up with the others view of version, causing it to be different among reads, which can lead to a livelock.

Comment 12 Mike Cao 2010-11-04 02:57:30 UTC

Verify this issue on :
# uname -r
2.6.18-229.el5
# rpm -q kvm
kvm-83-207.el5

steps:,start 7 guest on 8cores host with -no-kvm-pit-reinjection  -rtc-td-hack -startdate now

actual results:all guests didn't observe large offset(all less than 3s) after boot,pass.

this issue has already been fixed.

Comment 15 errata-xmlrpc 2011-01-13 23:35:32 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-2011-0028.html