Re: [PATCH V3 2/2] perf/x86: Reset the dirty counter to prevent the leak for an RDPMC task

[Liang, Kan]

On 4/13/2021 8:34 PM, Andy Lutomirski wrote:
> On Tue, Apr 13, 2021 at 12:05 PM <kan.liang@xxxxxxxxxxxxxxx> wrote:
> > From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> >
> > The counter value of a perf task may leak to another RDPMC task.
> > For example, a perf stat task as below is running on CPU 0.
> >
> >      perf stat -e 'branches,cycles' -- taskset -c 0 ./workload
>
> I assume this doesn't fix the leak if the sensitive counter is systemwide?

Right.

> Could Intel please add proper security and ideally virtualization for
> this?  Ideally RDPMC permission would be a bitmask for all RDPMC-able
> counters, not just a single on/off switch.

Yes, we are working on it.

For now, I think this patch is what we can do so far.

Thanks,
Kan