Description of problem:

I have a variety of virt images on my laptop. If I attempt to boot them under 3.18.4-200.fc21 and later (including the latest update 3.18.5-201.fc21), I get:

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

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 89, in
cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 125, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1388, in
startup
    self._backend.create()
  File "/usr/lib64/python2.7/site-packages/libvirt.py", line 999, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: unsupported configuration: guest and host CPU are not
compatible: Host CPU does not provide required features: rtm, hle

kernel-3.18.3-201.fc21 and earlier work fine.

I assume this is because the kernel has some updated microcode (or similar) and is now correctly disabling HLE?

Version-Release number of selected component (if applicable):

kernel-3.18.4-200.fc21 and later

How reproducible:

100%

Steps to Reproduce:
1. boot system
2. attempt to start virt images

Actual results:

Fails

Expected results:

Succeeds in some reasonable way.

Additional info:

qemu-system-x86-2.1.3-1.fc21.x86_64, if it matters.