Please patch the CentOS-virt Kernel to fix the Kernel Side-Channel Attacks vulnerabilities. The latest CentOS-virt kernel was released in November, as seen below. kernel-4.9.63-29.el7.x86_64.rpm 2017-11-21 13:30 https://access.redhat.com/security/vulnerabilities/speculativeexecution http://mirror.centos.org/centos/7/virt/x86_64/xen/