Re: [PATCH v8 09/12] x86/HVM: scale MPERF values reported to guests (on AMD)

[Jan Beulich <jbeulich@xxxxxxxx>]

On 05.05.2020 10:17, Jan Beulich wrote:
> AMD's PM specifies that MPERF (and its r/o counterpart) reads are
> affected by the TSC ratio. Hence when processing such reads in software
> we too should scale the values. While we don't currently (yet) expose
> the underlying feature flags, besides us allowing the MSRs to be read
> nevertheless, RDPRU is going to expose the values even to user space.
> 
> Furthermore, due to the not exposed feature flags, this change has the
> effect of making properly inaccessible (for reads) the two MSRs.
> 
> Note that writes to MPERF (and APERF) continue to be unsupported.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Sorry, just re-sent this one with correct numbering.

Jan