An issue was discovered in Xen through 4.9.x on the ARM platform allowing guest OS users to obtain sensitive information from DRAM after a reboot, because disjoint blocks, and physical addresses that do not start at zero, are mishandled.
https://xenbits.xen.org/xsa/advisory-245.html
https://security.gentoo.org/glsa/201801-14
https://lists.debian.org/debian-lts-announce/2018/10/msg00009.html