Re: Unmapping KVM Guest Memory from Host Kernel

Manwaring, Derek
2024-03-08T21:05:22Z

On 2024-03-08 at 10:46-0700, David Woodhouse wrote:
> On Fri, 2024-03-08 at 09:35 -0800, David Matlack wrote:
> > I think what James is looking for (and what we are also interested
> > in), is _eliminating_ the ability to access guest memory from the
> > direct map entirely. And in general, eliminate the ability to access
> > guest memory in as many ways as possible.
>
> Well, pKVM does that...

Yes we've been looking at pKVM and it accomplishes a lot of what we're trying
to do. Our initial inclination is that we want to stick with VHE for the lower
overhead. We also want flexibility across server parts, so we would need to
get pKVM working on Intel & AMD if we went this route.

Certainly there are advantages of pKVM on the perf side like the in-place
memory sharing rather than copying as well as on the security side by simply
reducing the TCB. I'd be interested to hear others' thoughts on pKVM vs
memfd_secret or general ASI.

Derek