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SubjectRe: [PATCH] x86/nospec: Unwreck the RSB stuffing
On Tue, Aug 16, 2022 at 03:01:33PM +0200, Borislav Petkov wrote:
> On Tue, Aug 16, 2022 at 12:52:58PM +0000, Andrew Cooper wrote:
> > One minor point.  Stuff 32 slots.
> >
> > There are Intel parts out in the world with RSBs larger than 32 entries,
> > and this loop does not fill the entire RSB on those.
> >
> > This is why the 32-entry stuffing loop is explicitly not supported on
> > eIBRS hardware as a general mechanism.
> I'm guessing there will be an Intel patch forthcoming, making that
> RSB_CLEAR_LOOPS more dynamic, based on the current model.

This is being discussed internally, but likely Enhanced IBRS parts don't
need RSB stuffing (except for the single entry stuffing for mitigating

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