Re: KVM PMU virtualization

Joerg Roedel
2010-02-28T16:34:34Z

On Fri, Feb 26, 2010 at 04:14:08PM +0100, Peter Zijlstra wrote:
> On Fri, 2010-02-26 at 16:53 +0200, Avi Kivity wrote:
> > > If you give a full PMU to a guest it's a whole different dimension and quality
> > > of information. Literally hundreds of different events about all sorts of
> > > aspects of the CPU and the hardware in general.
> > >
> >
> > Well, we filter out the bad events then.
>
> Which requires trapping the MSR access, at which point a soft-PMU is
> almost there, right?

The perfctl msrs need to be trapped anyway. Otherwise the guest could
generate NMIs in host context. But access to the perfctr registers could
be given to the guest.

Joerg