[libvirt-users] CPU model and missing AES-NI extension

[Michal Privoznik]

On 04.02.2015 22:32, Dennis Jacobfeuerborn wrote:
> Hi,
> today I tried to configure a guest using Virt-Manager and used the "copy
> host cpu configuration" option which resultet in a "Sandy Bridge" model.
> What I noticed is that for example the "aes" extension is not available
> in the guest even though it is available on the host cpu.
> 
> This is what the host cpu looks like:
> 
> model name	: Intel(R) Xeon(R) CPU E5-2650 v3 @ 2.30GHz
> flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
> pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx
> pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl
> xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor
> ds_cpl vmx smx est tm2 ssse3 fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2
> x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm
> abm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority
> ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid
> 
> And this is what I get in the guest:
> 
> model name	: Intel Xeon E312xx (Sandy Bridge)
> flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
> pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb lm
> constant_tsc pni ssse3 cx16 sse4_1 sse4_2 popcnt lahf_lm abm
> 
> Is there a way to get closer to the hardware and get as many of the host
> features in the guest as possible? I never intend to do anything like
> live-migration with this guest so compatibility for that case is not a
> concern.
> 

I think this is XML snippet you're aiming for:

  <cpu mode='host-model'>
    <model fallback='allow'/>
  </cpu>


Michal