On 21/10/19 16:09, Vitaly Kuznetsov wrote:
>>> + if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_ON) {
>>> + env->features[FEAT_HV_RECOMM_EAX] |= HV_NO_NONARCH_CORESHARING;
>>> + } else if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_AUTO) {
>> Do you want to make auto the default if "-cpu host,migratable=off"? It
>> can be done on top so I started queueing this patch.
> Hm, one thing is that CPUID 0x40000004 doesn't exist if no Hyper-V
> enlightenments are passed so we'll probably have to modify your idea to
> "-cpu host,migratable=off,+any-hyperv-enlightenment" but then the
> question is how conservative are we, like if QEMU command line doesn't
> change can new CPUID flags appear or not? And we'll probably need a way
> to explicitly disable HV_NO_NONARCH_CORESHARING if needed.
I would defer to Eduardo on whether "migratable=off" would allow adding
new CPUID flags. The follow-up question however is whether we would
benefit from a "+hyperv" option that enables all known Hyper-V
enlightenment for a given machine type.
Paolo
