https://www.theregister.co.uk/2019/06/26/amd_epyc_key_security_flaw/

Microchip slinger AMD has issued a firmware patch to fix the encryption in its Secure Encrypted Virtualization technology (SEV), used to defend the memory of Linux KVM virtual machines running on its Epyc processors.

"Through ongoing collaboration with industry researchers AMD became aware that, if using the user-selectable AMD secure encryption feature on a virtual machine running the Linux operating system, an encryption key could be compromised by manipulating the encryption technology’s behavior," an AMD spokesperson told The Register last night.