Re: [PATCHv2 12/14] x86/mm: Implement page_keyid() using page_ext

[Dave Hansen]

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?