> On Wed, Feb 07, 2024, Xin Li wrote:
> > Clear FRED VM entry/exit controls when initializing a vCPU, and set
> > these controls only if FRED is enumerated after set CPUID.
> >
> > FRED VM entry/exit controls need to be set to establish context
> > sufficient to support FRED event delivery immediately after VM entry
> > and exit. However it is not required to save/load FRED MSRs for
> > a non-FRED guest, which aren't supposed to access FRED MSRs.
>
> Does this actually provide a measurable performance boost? If not, just do the
> unnecessary load/store on entry/exit.
No performance measurement yet. Will make the change.
>
> Generally speaking, the only time KVM dynamically toggles entry/exit controls is
> when KVM wants to run the guest with a host value, e.g. with the host's
> PERF_GLOBAL_CTRL.
Simple rule.
Thanks!
Xin
