Re: [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code

Borislav Petkov
2020-11-17T21:23:27Z

On Tue, Nov 17, 2020 at 08:02:51PM +0100, Alexandre Chartre wrote:
> No. This prevents the guest VM from gathering data from the host
> kernel on the same cpu-thread. But there's no mitigation for a guest
> VM running on a cpu-thread attacking another cpu-thread (which can be
> running another guest VM or the host kernel) from the same cpu-core.
> You cannot use flush/clear barriers because the two cpu-threads are
> running in parallel.

Now there's your justification for why you're doing this. It took a
while...

The "why" should always be part of the 0th message to provide
reviewers/maintainers with answers to the question, what this pile of
patches is all about. Please always add this rationale to your patchset
in the future.

Thx.

--
Regards/Gruss,
Boris.