Unknown NMI reason 20 and 30 on a VM

I pulled up the console on a virtual machine I manage today and was greeted with some kernel messages: [5912557.130943] Uhhuh. NMI received for unknown reason 20 on CPU 0. [5912557.131115] Do you have a strange power saving mode enabled? [5912557.131287] Dazed and confused, but trying to continue [6064281.393568] Uhhuh. NMI received for unknown reason 30 on CPU 1. [6064281.393888] Do you have a strange power saving mode enabled? [6064281.394235] Dazed and confused, but trying to continue That's just a few of them, both 20 and 30 occur on CPU 0 and 1. - VM is Debian Jessie, BIOS boot ("QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014"; kernel 3.16.0-4-amd64) - Hypervisor is libvirt/KVM running on Debian testing (currently Debian's 4.7.0-1-amd64; qemu 1:2.7+dfsg-3). - Hardware is an Opteron 6344 on a [Supermicro H8SGL-F](http://www.supermicro.com/Aplus/motherboard/Opteron6000/SR56x0/H8SGL-F.cfm) with ECC RAM with scrub enabled. I don't see any NMI or EDAC error/warning messages on the host. Any idea what is causing these NMI messages on the guest? Are they anything to worry about? (May be related to https://unix.stackexchange.com/questions/216925/nmi-received-for-unknown-reason-20-do-you-have-a-strange-power-saving-mode-ena but that appears to be bare metal).