Issued:
2009-10-08
Updated:
2009-10-08

RHBA-2009:1488 - kvm bug fix update

Synopsis

kvm bug fix update

Type/Severity

Bug Fix Advisory

Topic

Updated kvm packages that resolved two issues are now available.

Description

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. (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 with BZ#518081, the original Bugzilla report for this issue.

This content is not included.http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Technical_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.

Solution

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

The update is available via the Red Hat Network (RHN). To apply package updates via the RHN see http://kbase.redhat.com/faq/docs/DOC-11259

After installation, use the following procedure to ensure the fixes take effect.

  1. Stop all KVM guest virtual machines (VMs).

  2. Reboot the host (hypervisor) system.

  3. Restart the KVM guest VMs.

If re-booting the host system is not possible, an alternative to step 2 above is as follows:

2a. Determine which of the following modules are running using the "lsmod" command: kvm, ksm, kvm-intel or kvm-amd.

2b. Remove each running module using the "modprobe -r [module]" command. (If kvm is running, for example, the "modprobe -r kvm" command removes it.)

2c. Reload each running module using the "modprobe [module]" command. (For example, to reload kvm, use the "modprobe kvm" command.)

Note: removing and reloading a running module can only be done as the superuser.

Affected Products

ProductVersionArch
Red Hat Enterprise Linux for x86_64 - Extended Update Support5.4x86_64
Red Hat Enterprise Linux Workstation5x86_64
Red Hat Enterprise Linux Server5x86_64

Updated Packages

  • kvm-83-105.el5_4.9.x86_64.rpm
  • kmod-kvm-83-105.el5_4.9.x86_64.rpm
  • kvm-tools-83-105.el5_4.9.x86_64.rpm
  • kvm-qemu-img-83-105.el5_4.9.x86_64.rpm
  • kvm-83-105.el5_4.9.src.rpm

Fixes

CVEs

(none)

References

Additional information