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.
Exploitability
AV:LAC:MAu:NImpact
C:NI:NA:C4.7/AV:L/AC:M/Au:N/C:N/I:N/A:C