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