Re: [PATCH v2 1/3] KVM: x86: add support for user wait instructions

[Paolo Bonzini]

On 29/05/19 04:05, Tao Xu wrote:
>>
> 
> Thank you Paolo, but I have another question. I was wondering if it is
> appropriate to enable X86_FEATURE_WAITPKG when QEMU uses "-overcommit
> cpu-pm=on"?

"-overcommit" only establishes the behavior of KVM, it doesn't change
the cpuid bits.  So you'd need "-cpu" as well.

Paolo

> Or just enable X86_FEATURE_WAITPKG when QEMU add the feature
> "-cpu host,+waitpkg"? User wait instructions is the wait or pause
> instructions may be executed at any privilege level, but can use
> IA32_UMWAIT_CONTROL to set the maximum time.