major.io words of wisdom from a systems engineer

Late night virtualization frustration with kvm

I dragged out an old Aopen MP57-D tonight that was just sitting in the closet and decided to load up kvm on Fedora 18. I soon found myself staring at a very brief error message upon bootup:

kvm: disabled by bios

After a reboot, the BIOS screen was up and I saw that Virtualization and VT-d were both enabled. Trusted execution (TXT) was disabled, so I enabled it for kicks and rebooted. Now I had two errors:

kvm: disable TXT in the BIOS or activate TXT before enabling KVM
kvm: disabled by bios

Time for another trip to the BIOS. I disabled TXT, rebooted, and I was back to the same error where I first started. A quick check of /proc/cpuinfo showed that I had the right processor extensions. Even the output of lshw showed that I should be ready to go. Some digging in Google led me to a blog post for a fix on Dell Optiplex hardware.

The fix was to do this:

  1. Within the BIOS, disable virtualization, VT-d, and TXT
  2. Save the BIOS configuration, reboot, and pull power to the computer at grub
  3. Within the BIOS, enable virtualization and VT-d but leave TXT disabled
  4. Save the BIOS configuration, reboot, and pull power to the computer at grub
  5. Boot up the computer normally

Although it seems a bit archaic, this actually fixed my problem and set me on my way.