Messages in this thread | | | Date | Thu, 29 Mar 2018 15:43:38 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCHv2 12/14] x86/mm: Implement page_keyid() using page_ext |
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On Wed, Mar 28, 2018 at 09:59:23AM -0700, Dave Hansen wrote: > On 03/28/2018 09:55 AM, Kirill A. Shutemov wrote: > > +static inline int page_keyid(struct page *page) > > +{ > > + if (!mktme_nr_keyids) > > + return 0; > > + > > + return lookup_page_ext(page)->keyid; > > +} > > This doesn't look very optimized. Don't we normally try to use > X86_FEATURE_* for these checks so that we get the runtime patching *and* > compile-time optimizations?
I didn't go to micro optimization just yet. I would like to see whole stack functioning first.
It doesn't make sense to use cpu_feature_enabledX86_FEATURE_TME) as it would produce false-positives: MKTME enumeration requires MSR read.
We may change mktme_nr_keyids check to a static key here. But this is not urgent.
-- Kirill A. Shutemov
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