RHBA-2010:0855 - Bug Fix Advisory

Topic

Updated qemu-kvm packages that fix various bugs are now available for Red Hat
Enterprise Linux 6.

Description

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux
on AMD64 and Intel 64 systems. qemu-kvm is the user-space component for running
virtual machines using KVM.

This update fixes the following bugs:

• Prior to this update, virtio-net used a packet transmission algorithm that was

using a timer to delay a transmission in an attempt to batch multiple packets
together. However, this typically resulted in a higher latency. With this
update, the default algorithm has been changed to use an asynchronous bottom
half transmitter, improving the performance. (BZ#633963)

• Due to error in the committed_memory() function, the ksmtuned service was

unable to determine the correct amount of memory used by qemu-kvm processes when
no such process existed. This has been fixed, the relevant part of the source
code has been corrected to return 0 when no qemu-kvm process is found, and
ksmtuned now works as expected. (BZ#634249)

• Previously, attempting to commit a copy-on-write image to a raw backing disk

image using the "quemu-img commit" command may have failed with the following
error:

qemu-img: Error while committing image

With this update, this error no longer occurs, and such images can now be
committed as expected. (BZ#641835)

All users are advised to upgrade to these updated packages, which resolve these
issues.

Solution

Before applying this update, make sure that all previously-released errata
relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use the Red
Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64

Fixes

• BZ - 633963 - Replace virtio-net TX timer mitigation with bottom half handler
• BZ - 634249 - incorrect committed memory on idle host
• BZ - 641835 - Can not commit copy-on-write image's data to raw backing-image

CVEs

(none)

References

(none)