Re: [PATCH for-4.14] x86/msr: Disallow access to Processor Trace MSRs

[Michał Leszczyński <michal.leszczynski@xxxxxxx>]

----- 19 cze 2020 o 13:58, Andrew Cooper andrew.cooper3@xxxxxxxxxx napisał(a):

> We do not expose the feature to guests, so should disallow access to the
> respective MSRs.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Paul Durrant <paul@xxxxxxx>
> CC: Michał Leszczyński <michal.leszczynski@xxxxxxx>
> 
> Paul: For 4.14.  This needs backporting to older trees as well.
> 
> Michał: CC'ing, just to keep you in the loop.  Xen has some dubious default
> MSR semantics which we're still in the middle of untangling in a backwards
> compatible way.  Patches like this will eventually not be necessary, but they
> are for now.


As for external IPT monitoring, it would be best if the VM would think
that IPT is simply not supported at all by the underlying hypervisor.


Best regards,
Michał Leszczyński
CERT Polska