Re: [PATCH v11 2/7] x86/kvm/hyper-v: Simplify addition for custom cpuid leafs

On 13/05/20 14:49, Jon Doron wrote:

quoted

To be honest from my understanding of the TLFS it states:
"The maximum input value for hypervisor CPUID information."

So we should not expose stuff we wont "answer" to, I agree you can
always issue CPUID to any leaf and you will get zeroes but if we try to
follow TLFS it sounds like this needs to be capped here.

I think Roman is right in the reading, but it's also nicer to have a
capped EAX because you can just look at EAX and guess what features are
there (it's simpler than looking for zeroes).

Paolo