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Description of problem: When trying to set up a virtual machine on a CPU E7-8870 (Westmere) it shows that the invtsc feature cannot be used inside the domain XML. According to the output of # virsh capabilities this should be the case. Version-Release number of selected component (if applicable): - kernel-3.10.0-327.10.1.el7.x86_64 - libvirt-1.2.17-13.el7_2.3 How reproducible: Set up a RHEL7.2 VM on an RHEL7.2 hypervisor Steps to Reproduce: 1. Install the VM 2. Start it with <cpu mode='host-model'> inside XML 3. The flag nonstop_tsc isn't present in /proc/cpuinfo as invtsc is missing 4. Add to XML: <feature policy='require' name='invtsc'/> 5. Try to start the VM with virsh start <domain> Actual results: Error message: error: Failed to start domain ls3059v1 error: unsupported configuration: host doesn't support invariant TSC Expected results: VM starts Additional info:
Would you mind sharing the output of virsh capabilities and /proc/cpuinfo from the host?
Created attachment 1132364 [details] Output of virsh capabilities
Created attachment 1132365 [details] output of cat /proc/cpuinfo
This appears to also be the case for Sandy Bridge. I have the same setup - RHEL 7.2 host, virsh capabilities does show invtsc, I added to my xml as <feature policy='require' name='invtsc'/> and get no errors at define or guest start up. I do not see invtsc in /proc/cpuinfo for either the host or guest. The qemu process does not have it either. Dave
The RHEL7 hypervisor (qemu-kvm from the qemu-kvm package) does not support invtsc. The support is only in the RHEV hypervisor (qemu-kvm from the qemu-kvm-rhev package). I suggest closing this as NOTABUG. The feature shows in /proc/cpuinfo as nonstop_tsc, not invtsc.
Thanks to Jan Tomko we now have a reliable status about qemu-kvm in RHEL7.2. What we checked out now: 1. Subscribed the system to the RHEV channel 2. Installed the quemu-kvm-rhev package which updated qemu-kvm 3. Switched the guest off and on again 4. The desired CPU flags {constant,nonstop}_tsc are now visible within the guest. So we can close this bug for now. Thank you all.
Closing as per comment #7
*** Bug 1625014 has been marked as a duplicate of this bug. ***