RHBA-2014:1490 - Bug Fix Advisory

Topic

Updated qemu-kvm packages that fix several bugs and add various enhancements 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. The qemu-kvm package provides the user-space
component for running virtual machines using KVM.

This update fixes the following bugs:

• Repeated creation of virtual machine (VM) image snapshots gradually increases

the string size of the image filename. However, the number of characters in the
filename strings for virtual VM images was previously limited to 1024.
Consequently, when the size limit was reached, creating an image snapshot failed
to be executed or the VM did not successfully boot. With this update, the
filename string size limit has been increased to 4096, and the described
problems only occur with an extremely high amount of snapshots. (BZ#1067576)

• Vendor-specific SCSI commands issued from a KVM guest did not reach the target

device because QEMU regarded such commands as invalid. This bug has been fixed
and vendor-specific SCSI commands are now properly propagated to the target
device. (BZ#1113917)

• Previously, the bdrv_is_allocated() function returned "True" for unallocated

sectors. Consequently, when performing live incremental migration, the disk size
was in some cases considerably expanded due to unintended transfer of
unallocated sectors beyond the end of the base image. With this update, the
bdrv_is_allocated() returns "False" for unallocated sectors. As a result, the
disk size no longer changes in the mentioned scenario. (BZ#1092117)

• When hot unplugging a virtual CPU (vCPU) from a guest using libvirt, the

current Red Hat Enterprise Linux QEMU implementation does not remove the
corresponding vCPU thread. Consequently, libvirt did not detect the vCPU count
correctly after a vCPU was hot unplugged, and it was not possible to hot plug a
vCPU after a hot unplug. In this update, information from QEMU is used to filter
out inactive vCPU threads of disabled vCPUs, which allows libvirt to perform the
hot plug. (BZ#1017858)

• The "dump-guest-memory" command did not correctly support memory compression,

which caused crash dump files to take up excessive hard drive space. The memory
compression of "dump-guest-memory" has now been fixed, and the crash dump files
now have the expected size. (BZ#1035162)

In addition, this update adds the following enhancements:

• The ioeventfd mechanism has been enabled in the virtio-scsi-pci controller.

This allows QEMU to process I/O requests outside of the vCPU thread, which
reduces the latency of submitting requests and improves single task throughput.
(BZ#1106420)

• A new device, virtio-rng, can be configured for guests, which makes the

entropy from the host available to guests. By default, this information is
sourced from the host's /dev/random file, but hardware random number generation
(RNG) available on hosts can be used as the source as well. (BZ#786407)

• The dump-guest-memory.py script has been introduced into QEMU, which makes it

possible to analyze a guest memory dump from the QEMU-KVM core in case of a
guest kernel failure. (BZ#826266)

• KVM now supports the use of a virtualized Performance Monitoring Unit (vPMU).

This allows users to run performance monitoring tools on Linux guests, as well
as to perform a live guest migration while using PMU. (BZ#845667)

• The qemu-img utility is now able to create images in the VHD and VHDX format,

which can be used with the Microsoft Hyper-V hypervisor. (BZ#1006159,
BZ#1097021)

• The support for version 3 of the Virtual Machine Disk (VMDK) format has been

added to the qemu-img utility. This allows qemu-img to read image info and
convert the format of VMDK3 image files. (BZ#1007708)

Users of qemu-kvm are advised to upgrade to these updated packages, which fix
these bugs and add these enhancement. After installing this update, shut down
all running virtual machines. Once all virtual machines have shut down, start
them again for this update to take effect.

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
https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• 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 from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386

Fixes

• BZ - 786407 - [RFE] Add ability to pull system entropy from host
• BZ - 949547 - qemu-kvm process consumes 8% cpu even when windows guest is idle inside and 70% when guest uses 10% cpu inside
• BZ - 965396 - turn down tap link off under hmp, rhel6.4 guest boot stalled at "starting certmonger" after “system-reset”
• BZ - 990254 - qemu-kvm failing when invalid machine type is provided
• BZ - 994388 - SpiceWorker-CRITICAL **: red_worker.c:4894:red_update_area: condition `area->left >= 0 && area->top >= 0 && area->left < area->right && area->top < area->bottom' failed
• BZ - 995931 - Qemu core dump (red_get_image: unknown type 184) when reboot a RHEL.6.4-64 guest 25 times
• BZ - 998426 - there are four "gluster" in qemu-img supported format list
• BZ - 998865 - Add vlan parameter in device_add command would cause device_add qemu_new_net_client: Assertion `!peer'
• BZ - 1004420 - Backport qcow2 corruption prevention patches
• BZ - 1005037 - When using “-vga qxl” together with “-display vnc=:5” or “-display sdl” qemu displays pixel garbage
• BZ - 1006027 - -mem-prealloc option behaviour is opposite to expected
• BZ - 1006159 - [RFE] qemu-img: Add/improve support for VHD/VHDX format
• BZ - 1006650 - qemu should give a more friendly prompt when didn't specify read-only for VHDX format disk
• BZ - 1007708 - [RFE] Enable qemu-img to support VMDK version 3
• BZ - 1007712 - host call trace while chang the number of VFs through sysfs with VF in use
• BZ - 1008755 - should block to do live migration when trying to migrate a VHDX image file
• BZ - 1008761 - qemu should give a more friendly prompt when didn't specify read-only for VPC format disk
• BZ - 1010670 - spice session is closed when taking snapshot with ram
• BZ - 1012244 - make live snapshot with QED disk specified qcow2 format will cause guest hang and host call trace
• BZ - 1013300 - Guest coredump while boot guest with " MALLOC_PERTURB_=234 ....--vnc :10,acl,sasl -vga qxl"
• BZ - 1017649 - need to update qmeu-img man help docs page about "VHDX" format disk
• BZ - 1017858 - [Intel 6.6 Bug] virsh setvcpus can not setup correct vcpu number
• BZ - 1018434 - qemu-kvm: Could not find keytab file: /etc/qemu/krb5.tab: No such file or directory
• BZ - 1018451 - 'qemu-img info' take too much time with 'cluster_size=512,preallocation=metadata' in the first time
• BZ - 1018537 - qemu core dump after run read/randwr fio in guest with usb or scsi disk
• BZ - 1021575 - Missing SASL support for SPICE
• BZ - 1022548 - Read/Randread/Randrw performance regression
• BZ - 1023874 - [Regression] Prompt error of trigger blkdebug: BLKDBG_CLUSTER_FREE event is not the same as expected
• BZ - 1024335 - Manpage doesn't document -drive rerror/werror/readonly
• BZ - 1025235 - the readonly permission of floppy will be changed after eject/change
• BZ - 1026903 - QMP: human-monitor-command: fix buffer duplication
• BZ - 1027181 - Guest can't receive any character transmitted from host after hot unplugging virtserialport then hot plugging again
• BZ - 1027561 - Cleanup unused event_idx compat property from rhel6.0.0 and rhel6.1.0 machine types
• BZ - 1029983 - spice-server reports incorrect listening address on monitor with "ipv6" option
• BZ - 1031883 - qemu-io error prompt "Operation is supported" is not expected
• BZ - 1054137 - improve error reporting
• BZ - 1054753 - qemu-img doesn't print error in json for raw images
• BZ - 1060024 - QMP socket breaks on unexpected close
• BZ - 1063559 - VHDX: journal log should not be replayed by default, but rather via qemu-img check -r all
• BZ - 1064643 - qemu makes no distinction between external and guest triggered block I/O errors
• BZ - 1067576 - RHEV: Cannot start VMs that have more than 23 snapshots.
• BZ - 1074396 - QMP: "query-version" doesn't include the -rhev prefix from the qemu-kvm-rhev package
• BZ - 1074762 - qemu-kvm Segmentation fault when using -no-kvm-irqchip option and virtio-nic-pci device as the same time
• BZ - 1075139 - multi-monitor doesn't work with a RHEL 7 guest.
• BZ - 1088610 - qemu-img coredumpd when try to create a gluster format image
• BZ - 1088788 - qemu-img creates truncated VMDK image with subformat=twoGbMaxExtentFlat
• BZ - 1092117 - live incremental migration of vm with common shared base, size(disk) > size(base) transfers unallocated sectors, explodes disk on dest
• BZ - 1095609 - qemu-kvm should give some hint when hot-plug a devices with the same existing "scsi-id and lun"
• BZ - 1095612 - Machine type rhel6.0.0 & -vga qxl & vnc cause qemu-kvm core dump
• BZ - 1097021 - [RFE] qemu-img: Add/improve Disk2VHD tools creating VHDX images
• BZ - 1097031 - Improve posix-aio-compat latency by backporting upstream fix
• BZ - 1099599 - Some vCPU topologies not accepted by libvirt
• BZ - 1101430 - qemu-kvm get "Unknown error 1539571707" when execute block-stream
• BZ - 1101701 - comparison always false at qcow2_refcount.c:613
• BZ - 1102659 - Use-after-free of file descriptor in create_kdump_vmcore
• BZ - 1102668 - Return value of virtio_load not checked in virtio_rng_load
• BZ - 1104573 - DMA error when install RHEL.5.11.x86_64 guest (ide drive) on RHEL6 host
• BZ - 1105428 - readonly=on has no effect for drive with no media
• BZ - 1106420 - Enable ioenventfd for virtio-scsi-pci
• BZ - 1112078 - RHEL7 guest desktop hang when boot with qxl and vnc
• BZ - 1116558 - Allow qemu-img to bypass the host cache (check, compare, convert, rebase, amend)
• BZ - 1118543 - Can not continue live commiting when using glusterfs(native) backend after relaunch qemu
• BZ - 1118718 - VMstate static checker: backport -dump-vmstate feature to export json-encoded vmstate info
• BZ - 1119207 - [rng]qemu-kvm process still can start when specify negative value for max-bytes
• BZ - 1120541 - qemu-kvm crashed when doing iofuzz testing
• BZ - 1122410 - backport qemu-iotests to the RHEL 6 internal repository
• BZ - 1122885 - qemu-img man doc should tell "should report progress bar when receives "SIGUSR1" signal if -p option is not used"
• BZ - 1122992 - Full mirroring with smaller backing file causes qemu to hang
• BZ - 1123698 - qemu-kvm core dump when hot-plug a virtio-scsi disk to guest and reboot
• BZ - 1124314 - incorrect event reported by QMP on hot plugging an in-use VF to guest
• BZ - 1124443 - qcow2 doesn't catch invalid header extension sizes
• BZ - 1125792 - Add vmstate json representation files for RHEL6 releases to source tree

CVEs

(none)

References

(none)