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.li...@linux.intel.com> wrote:

From: Kan Liang <kan.li...@linux.intel.com>

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