RHBA-2015:2555 - Bug Fix Advisory

Topic

Updated qemu-kvm-rhev packages that fix several bugs and add two enhancements are now available for Red Hat Enterprise Virtualization Hypervisor 7.

Description

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. The qemu-kvm-rhev packages provide the user-space component for running virtual machines using KVM in environments managed by Red Hat Enterprise Virtualization Manager.

This update fixes the following bugs:

• Prior to this update, cold-plugged memory could not be hot-unplugged. This update fixes the unplug procedure so that cold-plugged memory can be hot-unplugged. (BZ#1283072)
• Previously, unplugging memory in some cases caused the Linux kernel to terminate unexpectedly. This update fixes memory alignment so unplugging the memory does not cause the kernel to crash. (BZ#1278282)
• Starting a guest with NUMA did not allow the use of hugepages. With this update, guests correctly handle hugepages so that when they are using NUMA, hugepages can be used. (BZ#1279387)
• Previously, configuration properties in the Ceph configuration file could overwrite the QEMU command-line properties. This update fixes the order of applying Red Hat Ceph Storage settings so that correct values are used. (BZ#1279391)
• When running the GNU Debugger (GDB) on a KVM guest on IBM Power 8 hardware, GDB failed to check the hardware watchpoints. This update enables the necessary hypercalls so that GDB properly checks the hardware watchpoints. (BZ#1283073)
• Due to an unhandled error, the qemu-kvm process exited when trying to hot-plug memory devices on guests using 1GB hugepages. With this update, the error is handled within qemu-kvm, and as a result, the process does not crash. (BZ#1283079)

In addition, this update adds the following enhancements:

• The vhost-user multi-queue feature in QEMU is now available in qemu-kvm-rhev as Technology Preview. This feature enables the multi-queue functionality native to vhost, which provides a separate thread for each queue. (BZ#1276100)
• The vhost-user multi-queue live migration feature is now available as Technology Preview. This feature enables the multi-queue functionality to be used with live migration. (BZ#1279388)

Users of qemu-kvm-rhev are advised to upgrade to these updated packages, which fix these bugs and add these enhancements. 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.

For details on how to apply this update, refer to:

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

Affected Products

• Red Hat Virtualization 3 for RHEL 7 x86_64

Fixes

• BZ - 1278282 - memory unplug triggers BUG_ON: kernel BUG at mm/memory_hotplug.c:703!
• BZ - 1279387 - hugepage could not be used inside guest if start the guest with NUMA supported huge pages [7.2.z]
• BZ - 1279391 - ceph.conf properties override qemu's command-line properties
• BZ - 1283072 - cold-plugged DIMM can't be unplugged on the first unplug request
• BZ - 1283079 - qemu process exit after hot-plug a memory device which guest use 1G hugepages

CVEs

(none)

References

(none)