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SubjectRe: selftests/x86/fsgsbase_64 test problem
On Mon, Jan 29, 2018 at 10:30:05AM -0800, H. Peter Anvin wrote:
> On 01/29/18 10:26, Andy Lutomirski wrote:
> >>>
> >>> That will utterly suck on non-UMIP machines that have
> >>> hypervisor-provided UMIP emulation.
> >>
> >> Is that a valid thing to optimize for, especially given that paranoid
> >> entries aren't the most common anyway?
> >
> > A bunch of people seem to care about NMI performance for perf.
> >
>
> That wasn't really the question...
>
> > And the current patch set works without this trick.
>
> But I believe the tricks it uses are fragile.
>
> > FWIW, if we switch all entries to the entry text trampoline, we get direct percpu access for free.
>
> That might be a better option.

Has there been any conclusion to this thread? I can still reproduce the
issue on mainline and next.

Thanks,
Dan

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