Re: [PATCH v1] KVM: x86: PMU Whitelist

From: Eric Hankland
Date: Tue Jun 04 2019 - 12:00:45 EST

On Mon, Jun 3, 2019 at 9:37 PM Wei Wang <> wrote:

> So, I'm not sure if "quantifying LLC contention" has been proved to
> be a real issue. If this is considered to be an issue:
> - without PMU, we could also write a piece of software to run in the
> guest to quantify that contention (e.g. by analyzing the memory access
> latency). How do you prevent this?
> - the same thing could also happen with the L1 cache (e.g. a vCPU
> and a host thread run 2 logical CPUs on the same core). If this is disabled
> as well, we may have very few events usable, and would like to see what you
> have on the whitelist.

Right - I'm aware there are other ways of detecting this - it's still
a class of events that some people don't want to surface. I'll ask if
there are any better examples.