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?