RE: [Xen-devel] [Q] Allow rdpmc access from DOM-0

["Mohapatra, Hemant" <Hemant.Mohapatra@xxxxxxx>]

>  From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>  Subject: Re: [Xen-devel] [Q] Allow rdpmc access from DOM-0
>  
>  RDPMC is not much use unless you can also set up the
performance-counting
>  MSRs in advance to count appropriate things. Since we do not
virtualise
>  these MSRs, providing access to RDPMC is pointless. You should look
at
>  xenoprof for example usage of performance counter infrastructure in
Xen.


My bad; I should've mentioned this before: I already have allowed access
to the appropriate MSRs and can read/write to them using rdmsr/wrmsr on
DOM-0. It was easy to add them to the white-list since the opcode was
already being trapped and virtualized and it was only a matter of adding
access to the MSRs I needed specifically. 

I have worked with Xenoprof but I am essentially trying to port a few
applications to Xen here and trying to re-write them in conjunction with
Xenoprof seems like the round-about way of doing it. I am trying to
follow the route of how rdmsr/wrmsr were virtualized so that I can do
the same with rdpmc. I see no harm in this since RDMSR is already
allowed from Dom0.

Thanks,
Hemant



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