On Mon, Feb 20, 2023 at 10:52 AM Borislav Petkov <bp@xxxxxxxxx> wrote: > > On Mon, Feb 20, 2023 at 10:44:21AM -0800, KP Singh wrote: > > No it cannot with IBRS which is really just KERNEL_IBRS enabled, we > > See my other reply. The intent is there to be able to do it. What needs > to be figured out now is *why* we said no STIBP with IBRS? Was it an > omission or was there some intent behind it. > Sure, it looks like an omission to me, we wrote a POC on Skylake that was able to do cross-thread training with the current set of mitigations. STIBP with IBRS is still correct if spectre_v2=ibrs had really meant IBRS everywhere, but just means KERNEL_IBRS, which means only kernel is protected, userspace is still unprotected. > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
