Re: [PATCH 2/2] kvm/x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally

[Paolo Bonzini]

On 21/05/20 08:44, Tao Xu wrote:
> 
> I am sorry, I mean:
> By default, we don't expose WAITPKG to guest. For QEMU, we can use
> "-overcommit cpu-pm=on" to use WAITPKG.

But UMONITOR, UMWAIT and TPAUSE are not NOPs on older processors (which
I should have checked before committing your patch, I admit).  So you
have broken "-cpu host -overcommit cpu-pm=on" on any processor that
doesn't have WAITPKG.  I'll send a patch.

Paolo