linux-kernel - Re: [RFC, PATCH 21/22] x86/mm: Introduce page_keyid() and page

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Date:   Tue, 6 Mar 2018 17:58:06 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     "Kirill A. Shutemov" <kirill@...temov.name>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC, PATCH 21/22] x86/mm: Introduce page_keyid() and
 page_encrypted()

On Tue, Mar 06, 2018 at 02:56:08PM +0000, Dave Hansen wrote:
> On 03/06/2018 12:57 AM, Kirill A. Shutemov wrote:
> > On Mon, Mar 05, 2018 at 09:08:53AM -0800, Dave Hansen wrote:
> >> On 03/05/2018 08:26 AM, Kirill A. Shutemov wrote:
> >>> +static inline bool page_encrypted(struct page *page)
> >>> +{
> >>> +	/* All pages with non-zero KeyID are encrypted */
> >>> +	return page_keyid(page) != 0;
> >>> +}
> >>
> >> Is this true?  I thought there was a KEYID_NO_ENCRYPT "Do not encrypt
> >> memory when this KeyID is in use."  Is that really only limited to key 0.
> > 
> > Well, it depends on what we mean by "encrypted". For memory management
> > pruposes we care if the page is encrypted with KeyID different from
> > default one. All pages with non-default KeyID threated the same by memory
> > management.
> 
> Doesn't it really mean "am I able to use the direct map to get this
> page's contents?"

Yes.

Any proposal for better helper name?

-- 
 Kirill A. Shutemov