Description of problem: KVM doesn't work on Haswell systems. The latest kernel update broke KVM. I have three Fedora boxs, two Haswells and an Ivy Bridge. The Ivy Bridge seems to be working, the Haswells aren't. The VMs are RHEL 6.6 clones (Scientific Linux 6.6). Version-Release number of selected component (if applicable): 3.18.7-200.fc21.x86_64 How reproducible:100% Steps to Reproduce: 1.Start a virtual machine 2. 3. Actual results: Unsupported CPU error Expected results: Additional info: rror 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
This is already fixed upstream: https://www.redhat.com/archives/libvir-list/2014-December/msg00800.html That said, pasting Jan Tomko's suggestion from another bug[1] which is a duplicate of this[2]: update the guest XML config manually to omit those features: $ virsh edit VM . . . Disable the two CPU features: <cpu mode="custom" match="exact"> <model fallback="forbid">Haswell</model> <feature policy='disable' name='rtm'/> <feature policy='disable' name='hle'/> </cpu> And a comment from: Josh Boyer 2015-02-10 08:51:03 EST "As a bit more information, Intel pushed a firmware update that disabled the rtm/hle operations entirely because the TSX support in Hgaswell is broken in the chip. It works... until it doesn't. Fedora includes that microcode update and it is applied during early boot now." [1] https://bugzilla.redhat.com/show_bug.cgi?id=1190307 -- 3.18.4-200.fc21 (and later) cause guest/host CPU compatibility failures [2] https://bugzilla.redhat.com/show_bug.cgi?id=1182650 -- Can't launch any VM : rtm and hle CPU features flags needed by libvirt but not in /proc/cpuinfo *** This bug has been marked as a duplicate of bug 1182650 ***