A flaw was found in xen. In order to be certain that no undue access to memory is possible anymore after IOMMU mappings of this memory have been removed, Translation Lookaside Buffers (TLBs) need to be flushed after most changes to such mappings. Xen bypassed certain IOMMU flushes on AMD
x86 hardware. Furthermore logic exists Xen to re-combine small page mappings into larger ones. Such re-combination could have occured in cases when it was not really safe/correct to do so.
Name: the Xen project
Created xen tracking bugs for this issue:
Affects: fedora-all [bug 1651665]