[ovirt-users] ovirt 4.1 - skylake - no avx512 support in virtual machines

[Paolo Bonzini]

On 27/02/2018 09:37, Sandro Bonazzola wrote:
> 
> Virtual Machine settings
> A) VM:
> Custom CPU Type: Use cluster default(Intel Skylake Family)
> General Tab shows: Guest CPU Type: Skylake-Client
> 
> avx512: NO
> 
> B) VM:
> Custom CPU Type: Skylake-Client
> General Tab shows: Guest CPU Type: Skylake-Client
> 
> avx512: NO
> 
> C) VM:
> Custom CPU Type: Use cluster default(Intel Skylake Family) [grey -
> cannot modify]
> Migration mode: Do not allow migration
> Pass-Through Host CPU
> General Tab shows: Guest CPU Type: Skylake-Client
> 
> avx512: YES   ( cat /proc/cpuinfo  |grep avx512: avx512f avx512dq
> avx512cd avx512bw avx512vl )
> 
> Using pass-through host cpu (disabling vm migration) is the only way to
> access avx512 in a VM, is it a bug or am I missing something?

Skylake-Client does _not_ have AVX512 (I tried now on a Kaby Lake Core
i7 laptop).  Only Skylake-Server has it and it will be in RHEL 7.5.

Thanks,

Paolo