On 06/01/2020 16:37, Jan Beulich wrote:
> While the PM doesn't say so, this assumes that the MPERF value read this
> way gets scaled similarly to its reading through RDMSR.
>
> Also introduce the SVM related constants at this occasion.
>
> Signed-off-by: Jan Beulich <[email protected]>
> ---
> RFC: Andrew promised to take care of the CPUID side of this; will need
>      re-basing over his work once available.
> TBD: There are indications that the CPUID field used may be just 8 bits
>      wide.

Getting there.  The movement of CPU_POLICY into the migrate stream is a
substantial step in the right direction.

I've got half a mind to use RDPRU as the first real "need to opt-in"
feature, seeing as there currently isn't an answer for how APERF/MPERF
is virtualisation-safe in the first place, and how exposing it in
userspace is any better.

Perhaps better would be to make APERF/MPERF opt-in to begin with (so it
starts ceasing to exist for VMs by default, but in a backwards
compatible way), and then derive RDPRU as dependent on APERF/MPERF.

~Andrew

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