Description of problem: As bug 1182650 says, Haswell and Broadwell processors are patched to disable TSX instructions according to erratum released by Intel. This introduces VM incompatibility between Haswell processors with TSX and without TSX when explicitly specified as cpumodel='Haswell'. The upstream qemu introduced new cpu models, Haswell-noTSX and Broadwell-noTSX namely to address this issue. Bug 1182650 fixes the problem in the libvirt part. This bug intends to address qemu. Here's a link to the upstream commit: http://git.qemu.org/?p=qemu.git;a=commitdiff;h=a356850b80b3d13b2ef737dad2acb05e6da03753
qemu-2.1.3-8.fc21 has been submitted as an update for Fedora 21. https://admin.fedoraproject.org/updates/qemu-2.1.3-8.fc21
Package qemu-2.1.3-8.fc21: * should fix your issue, * was pushed to the Fedora 21 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing qemu-2.1.3-8.fc21' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2015-9599/qemu-2.1.3-8.fc21 then log in and leave karma (feedback).
qemu-2.1.3-8.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.