RHN Errata Alert: kvm bug fix update

[Red Hat Network Alert <dev-null@rhn.redhat.com>]

Red Hat Network has determined that the following advisory is applicable to
one or more of the systems you have registered:

Complete information about this errata can be found at the following location:
     https://rhn.redhat.com/rhn/errata/details/Details.do?eid=9242

Bug Fix Advisory - RHBA-2009:1488-1
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Summary:
kvm bug fix update

Updated kvm packages that resolved two issues are now available.

Description:
KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on x86 hardware. KVM can run multiple virtual machines running
unmodified Linux or Windows images. Each virtual machine has private
virtualized hardware: a network card, disk, graphics adapter, etc.

These updated packages fix the following bugs:

* the pthread_cond_timedwait time out was not properly handled.
Consequently, under some loads, some KVM guests stopped responding to
commands from the management interface. (Note: the reproducer was a host
running around 300 KVM guests with each guest consuming around 50% of their
virtual CPU. On this setup, some guests became non-responsive after several
hours.) With this update the time outs are handled properly and KVM guests
remain responsive, as expected. (BZ#526244)

* some Linux-based guests that used virtio virtual block devices aborted
during installation, returning the error message: "unhandled vm exit: 0x31
vcpu_id 0".

Using an interface other than virtio for the guest virtual disk was a work
around documented in the Red Hat Enterprise Linux 5.4 Technical Notes Known
Issues for KVM. The work around was associated with BZ#518081, the original
Bugzilla report for this issue.

http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Technical_Notes/Known_Issues-kvm.html

With this update, the underlying issue (stale EPTP-tagged mappings possibly
being used when a virtual CPU or vcpu migrated to a different Physical CPU
or pcpu) has been addressed and the work around is no longer necessary:
Linux-based guests using virtio virtual block devices no longer abort
during installation. (BZ#527192)

All users of kvm are advised to upgrade to these updated packages, which
resolve this issue.

References:
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Technical_Notes/Known_Issues-kvm.html
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Taking Action
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You may address the issues outlined in this advisory in two ways:

     - select your server name by clicking on its name from the list
       available at the following location, and then schedule an
       errata update for it:
           https://rhn.redhat.com/rhn/systems/SystemList.do

     - run the Update Agent on each affected server.


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Affected Systems List
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This Errata Advisory may apply to the systems listed below. If you know that
this errata does not apply to a system listed, it might be possible that the
package profile for that server is out of date. In that case you should refresh 
the system's package profile by running *one* of the following commands as root 
on that system:

 * 'up2date -p' (on Enterprise Linux systems prior to RHEL5)
 * 'rhn-profile-sync' (on Enterprise Linux 5 or later) 

There is 1 affected system registered in 'Your RHN' (only systems for
which you have explicitly enabled Errata Alerts are shown).

Release   Arch       Profile Name
--------  --------   ------------


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