Xen 4.0, and 4.1, when running a 64-bit PV guest on “older” AMD CPUs, does not properly protect against a certain AMD processor bug, which allows local guest OS users to cause a denial of service (host hang) via sequential execution of instructions across a non-canonical boundary, a different vulnerability than CVE-2012-0217.
lists.opensuse.org/opensuse-security-announce/2012-11/msg00017.html
lists.opensuse.org/opensuse-security-announce/2012-11/msg00018.html
lists.xen.org/archives/html/xen-announce/2012-06/msg00002.html
secunia.com/advisories/51413
secunia.com/advisories/55082
security.gentoo.org/glsa/glsa-201309-24.xml
support.amd.com/us/Processor_TechDocs/25759.pdf
www.debian.org/security/2012/dsa-2501
www.securityfocus.com/bid/53961