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Bug Fix Advisory kvm bug fix update

Advisory: RHBA-2010:0536-1
Type: Bug Fix Advisory
Severity: N/A
Issued on: 2010-07-29
Last updated on: 2010-07-29
Affected Products: RHEL Desktop Multi OS (v. 5 client)
RHEL Virtualization (v. 5 server)

Details

Updated kvm packages that resolve several issues are now available.

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux
on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for the
standard Red Hat Enterprise Linux kernel. KVM can run multiple unmodified,
virtualized guest Windows and Linux operating systems.

These updated kvm packages provide fixes for the following bugs:

* the virtio-blk back end for qemu-kvm performed unnecessary zeroing of memory
on every I/O request, which reduced virtual guest performance. With this update,
the virtio-blk back end avoids spurious zeroing of request structures on each
I/O request, with the result that guest performance is increased. (BZ#604159)

* in the kvm kernel module, some internal KVM memory slots were incorrectly
being handled by copy-on-write after a fork() function call, which caused issues
when qemu-kvm ran child processes. This update fixes the handling of internal
KVM memory slots on fork() to avoid those issues. (BZ#610341)

* when using the Network File System (NFS), lseek(SEEK_END) operations resulted
in a GETATTR command being sent to th eserver, with the result that performance
was reduced on disk images over NFS. With this update, the pread() and pwrite()
functions are used instead of lseek(), read() and write(), with the result that
performance is increased when using NFS. (BZ#610344)

* following writing metadata to a QCOW2 disk image, metadata was not flushed,
which could have potentially caused the disk image to become corrupted in the
event of system disruption (such as a power outage). With this update, metadata
is flushed after being written, thus increasing QCOW2 image integrity, and
decreasing the likelihood of image corruption. (BZ#612507)

* when using QCOW2 disk images, certain I/O operation or disk space depletion
errors could potentially have caused image corruption or a virtual guest to stop
running. This was due to the improper error-handling code for QCOW2 disk images.
This has been fixed with this update so that the aforementioned types of errors
are handled correctly, thus increasing QCOW2 disk integrity in such situations.
(BZ#612508)

All KVM users should upgrade to these updated packages, which contain backported
patches to resolve these issues.


Solution

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

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

Updated packages

RHEL Desktop Multi OS (v. 5 client)

SRPMS:
kvm-83-164.el5_5.15.src.rpm
File outdated by:  RHSA-2014:0163
    MD5: 58b4e19cd3f66d8333f6326b19a84e2b
SHA-256: adbcdd89732940c037c79c1534d1ed11c89adcc686148f81931455e3ee5888ba
 
x86_64:
kmod-kvm-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: 5cf955190fe67688f1fa2b035dab7627
SHA-256: e785948f51ceae8f4cbbad68671c0b47aee370231035f25091760c48e54c8014
kvm-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: 2600b08d1e23597e801dd76c3473324b
SHA-256: df7af1c022f66692f3c8cce77cea1f7149b82e4abc625475fa2a371dd7e227d9
kvm-qemu-img-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: f6aefe7a4a55ea99763fcb4483ab12a4
SHA-256: ab9e648ebd61511a3f1c3fa9c2b35a85742e7fc70f16c52a5aa98327828e2dd2
kvm-tools-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: 2bf922b10c4a5723711c05fcad6d9180
SHA-256: 2e8a799ec72e856726edc9dcb2567cc05b311539f99ace5947f058d0b56dbd95
 
RHEL Virtualization (v. 5 server)

SRPMS:
kvm-83-164.el5_5.15.src.rpm
File outdated by:  RHSA-2014:0163
    MD5: 58b4e19cd3f66d8333f6326b19a84e2b
SHA-256: adbcdd89732940c037c79c1534d1ed11c89adcc686148f81931455e3ee5888ba
 
x86_64:
kmod-kvm-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: 5cf955190fe67688f1fa2b035dab7627
SHA-256: e785948f51ceae8f4cbbad68671c0b47aee370231035f25091760c48e54c8014
kvm-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: 2600b08d1e23597e801dd76c3473324b
SHA-256: df7af1c022f66692f3c8cce77cea1f7149b82e4abc625475fa2a371dd7e227d9
kvm-qemu-img-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: f6aefe7a4a55ea99763fcb4483ab12a4
SHA-256: ab9e648ebd61511a3f1c3fa9c2b35a85742e7fc70f16c52a5aa98327828e2dd2
kvm-tools-83-164.el5_5.15.x86_64.rpm
File outdated by:  RHSA-2014:0163
    MD5: 2bf922b10c4a5723711c05fcad6d9180
SHA-256: 2e8a799ec72e856726edc9dcb2567cc05b311539f99ace5947f058d0b56dbd95
 
(The unlinked packages above are only available from the Red Hat Network)

Bugs fixed (see bugzilla for more information)

604159 - virtio-blk: Avoid zeroing every request structure
610341 - fork causes trouble for vcpu threads
610344 - Excessive lseek() causes severe performance issues with vm disk images over NFS
612507 - qcow2 image corruption when using cache=writeback
612508 - Backport qcow2 fixes to RHEL 5



These packages are GPG signed by Red Hat for security. Our key and details on how to verify the signature are available from:
https://www.redhat.com/security/team/key/#package

The Red Hat security contact is secalert@redhat.com. More contact details at http://www.redhat.com/security/team/contact/