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Date:   Mon, 18 Jun 2018 13:07:21 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Kai Huang <kai.huang@linux.intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCHv3 09/17] x86/mm: Implement page_keyid() using page_ext
Message-ID: <20180618100721.qvm4maovfhxbfoo7@black.fi.intel.com>
References: <20180612143915.68065-1-kirill.shutemov@linux.intel.com>
 <20180612143915.68065-10-kirill.shutemov@linux.intel.com>
 <169af1d8-7fb6-5e1a-4f34-0150570018cc@intel.com>
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On Wed, Jun 13, 2018 at 06:20:10PM +0000, Dave Hansen wrote:
> > +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.

There's no MKTME CPU feature.

Well, I guess we can invent syntactic one or just use static key directly.

Let's see how it behaves performance-wise before optimizing this.

-- 
 Kirill A. Shutemov