[virt-tools-list] 2 questions

Daniel P. Berrangé berrange at redhat.com
Fri Feb 1 15:04:34 UTC 2019

On Fri, Feb 01, 2019 at 04:56:23PM +0200, Hetz Ben Hamo wrote:
> Hi,
> I hope I'm asking in the right place.
> First question: I'm using AMD Ryzen 2700 CPU, and the VM's were running
> super slow. Checking on the net, most of the docs shows that I should look
> at lscpu output which indeed shows that my CPU has SVM. However, it took me
> a bit more time to figure out that the kvm_amd module was not loaded
> because SVM was disabled in the BIOS, so my question is: Could the VMM team
> add a simple check before starting a VM if kvm-intel or kvm_amd modules are
> loaded and if not - show a warning message to enable VT-X/SVM on the
> BIOS/UEFI please?

FWIW,  virt-host-validate command line tool should report on this problem,
but of course you have to know it exists first, so wouldn't have helped
your situation.

> Second question: After enabling the SVM in the BIOS and restarting the VMM,
> the previously configured VM was still running super-slow. I recreated the
> VM and only the new VM was running fast, so I assume that a parameter not
> to use the SVM is written in the VM configuration? if so, where can I
> change it in the VM configuration GUI? (I thought it was related to the
> copy/mode of the CPU, which doesn't change things)

Whether to use TCG (emulation) or KVM (hardware acceleration) is in the
guest XML configuration.

I don't think its changable in the GUI.

If you use the command line tool 'virsh edit $GUESTNAME' as root you will

  <domain type='qemu'>

Just change that to 'kvm' instead.

|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

More information about the virt-tools-list mailing list