Unable to install a new DomU and on boot automatic start of DomU is delayed

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Environment

SUSE Linux Enterprise Server 11 Service Pack 1
SUSE Linux Enterprise Server 11 Service Pack 2

Situation

Update to xen-4.1.2_18-0.9.1 or later has been applied.

DomU's that should start on boot, are starting delayed (60 seconds).

It is not possible to create a new DomU with vm-install or using YaST(2).

When creating a new DomU the following is found in the /var/log/xen/xend.log:
[2012-08-21 16:16:33 11373] ERROR (XendDomainInfo:2624) (12, 'Cannot allocate
memory')

The following 130nm and 90nm (DDR1-only) AMD processors are subject of this problem:

First-generation AMD-Opteron(tm) single and dual core processors in either 939 or 940 packages:
- AMD Opteron(tm) 100-Series Processors
- AMD Opteron(tm) 200-Series Processors
- AMD Opteron(tm) 800-Series Processors
AMD Athlon(tm) processors in either 754, 939 or 940 packages
AMD Sempron(tm) processor in either 754 or 939 packages
AMD Turion(tm) Mobile Technology in 754 package

Resolution

Xen will not allow creation of DomU-s on this CPU for security reasons. Pass "allow_unsafe" as boot option to Dom0, when all the guest kernels are trusted or when creating new DomU's.

The automatic start from DomU's during boot is not prevented, but delayed for 60 seconds. Manually started DomU's are not affected by this update.

Cause

For more information see:

CVE-2012-2934 Report a denial of service issue on old, pre-SVM AMD CPUs (AMD Erratum 121).
AMD Erratum #121 is described in "Revision Guide for AMD Athlon 64 and AMD Opteron Processors":
http://support.amd.com/us/Processor_TechDocs/25759.pdf
TID: 5143795 (Release notes from the xen update)

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