Red Hat ENTERPRISE LINUX 5.5 - TECHNICAL NOTES Manual page 146

Chapter 1. Package Updates
1.94.2. RHBA-2009:1488: bug fix update
Note
This update has already been released (prior to the GA of this release) as errata
RHBA-2009:1488
Updated kvm packages that resolved two issues are now available.
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.
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(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
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BZ#518081
with , the original Bugzilla report for this issue.
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Technica l_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.
1.94.3. RHBA-2010:0158: bug fix update
Note
This update has already been released (prior to the GA of this release) as errata
RHBA-2010:0158
Updated kvm packages that resolved two issues are now available.
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https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=526244
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https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=518081
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https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=527192
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