I have some older servers in my oVirt 3.5.6 cluster (on CentOS 7.2) that have Nehalem model Xeon CPUs, so that's my cluster CPU type. When I try to install Windows Server 2012 R2 Essentials, it gets through the "copying files to disk" stage and to the first reboot, but then blue-screens with a KMODE_EXCEPTION_NOT_HANDLED error (right about the time it should be setting up devices). It does not appear to be related to any virtio driver (I tried with IDE disk, and with virtio-scsi and memory balloon disabled). I have Fedora 23 (of course newer qemu-kvm version) on my desktop (with a much newer Intel CPU), with the libvirt tools installed, so I installed Windows there, and it worked. If I step the CPU back to Nehalem, it fails the same way. Go forward one step to Westmere, and it works (the only CPU feature difference for libvirt appears to be aes, but configuring Nehalem+aes doesn't seem to work, so there's more to it than that). Windows Server 2012 R2 is supposed to still run on Nehalem CPUs, so I guess there's a bug in qemu-kvm's emulation or features? I do also have a couple of servers with Sandy Bridge CPUs in my cluster. Is there any practical way to restrict a VM to running on a couple of hosts (and then use a hook to override the CPU model)? -- Chris Adams <cma(a)cmadams.net&gt;