The AMD IOMMU support in Xen 4.2.x, 4.1.x, 3.3, and other versions, when using AMD-Vi for PCI passthrough, uses the same interrupt remapping table for the host and all guests, which allows guests to cause a denial of service by injecting an interrupt into other guests.
https://exchange.xforce.ibmcloud.com/vulnerabilities/81831
http://www.securityfocus.com/bid/57745
http://www.openwall.com/lists/oss-security/2013/02/05/7
http://www.debian.org/security/2013/dsa-2636
http://security.gentoo.org/glsa/glsa-201309-24.xml
http://secunia.com/advisories/55082
http://secunia.com/advisories/51881
http://rhn.redhat.com/errata/RHSA-2013-0847.html
http://lists.opensuse.org/opensuse-updates/2013-06/msg00049.html
http://lists.opensuse.org/opensuse-updates/2013-04/msg00052.html
http://lists.opensuse.org/opensuse-updates/2013-04/msg00051.html
http://lists.opensuse.org/opensuse-security-announce/2014-03/msg00021.html