KVM Virtual Machine Manager: Host CPU does not provide required features: aes

Question

I am using Ubuntu 12.04 64-bit. I am using OpenStack. The service is all working, but nova service is not working. Some got error is: hardware not supported, so I changed Processor > Configuration > Module > Westmere, but when I start the VM, I got an error message:

Error starting domain: unsupported configuration: 
guest and host CPU are not compatible: Host CPU does not provide required features: aes

Solution

You have set your guest CPU to have AES, but your host CPU does not have AES. Your host CPU can not expose a CPU flag that it does not have. Your options:

• Remove the AES CPU flag from the guest VM
• Switch to a VM host that has a CPU with AES instructions (list of compatible CPUs)