Re: [PATCHv3 09/17] x86/mm: Implement page_keyid() using page_ext

[Dave Hansen]

> +int page_keyid(const struct page *page)
> +{
> +     if (mktme_status != MKTME_ENABLED)
> +             return 0;
> +
> +     return lookup_page_ext(page)->keyid;
> +}
> +EXPORT_SYMBOL(page_keyid);

Please start using a proper X86_FEATURE_* flag for this.  It will give
you all the fancy static patching that you are missing by doing it this way.