On Sat, May 27, 2017 at 11:09:54AM -0400, Brian Gerst wrote:
> > static inline int pgd_none(pgd_t pgd)
> > {
> > + if (p4d_folded)
> > + return 0;
> > /*
> > * There is no need to do a workaround for the KNL stray
> > * A/D bit erratum here. PGDs only point to page tables
>
> These should use static_cpu_has(X86_FEATURE_LA57), so that it gets
> patched by alternatives.
Right, eventually we would likely need something like this. But at this
point I'm more worried about correctness than performance. Performance
will be the next step.
And I haven't tried it yet, but I would expect direct use of alternatives
wouldn't be possible. If I read code correctly, we enable paging way
before we apply alternatives. But we need to have something functional in
between.
I guess it will be fun :)
--
Kirill A. Shutemov
