On 04/18/2017 12:35 AM, Jiri Denemark wrote:
On Thu, Apr 13, 2017 at 16:11:26 -0600, Jim Fehlig wrote:
Hi All,
I've been doing some upgrade testing and noticed a problem starting some
existing VMs after upgrading qemu from 2.6 to 2.9 on one of my AMD machines.
Using libvirt 3.2.0 and qemu 2.6, I have no problems starting a VM with the
following machine/CPU config
<os>
<type arch='x86_64' machine='pc-i440fx-2.6'>hvm</type>
<boot dev='hd'/>
</os>
<cpu mode='custom' match='exact'>
<model fallback='allow'>Opteron_G4</model>
</cpu>
After upgrading qemu to 2.9 the VM fails to start with
error: the CPU is incompatible with host CPU: Host CPU does not provide required
features: svm
I see that qemu commit 75d373ef disables SVM in KVM mode, but that change was
made quite some time ago and pertains to all machine types > pc-i440fx-2.2.
Perhaps the problem was revealed by Jiri's recent libvirt changes to detect host
CPU model by asking qemu?
My knee-jerk reaction is to remove 'svm' from Opteron CPUs in cpu_map.xml, but
I'm far from the expert on the evolving CPU code in libvirt, so asking the
experts here for some guidance.
This issue should be fixed by "qemu: More CPU enhancements and fixes"
series [1], specifically patch 9/9. See the commit message for more
details.
[1] https://www.redhat.com/archives/libvir-list/2017-April/msg00710.html
Thanks. Although I haven't reviewed the series, I did test it and indeed it
fixes the issue.
Regards,
Jim
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