Re: [RFC, PATCH 21/22] x86/mm: Introduce page_keyid() and page_encrypted()

From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
	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>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC, PATCH 21/22] x86/mm: Introduce page_keyid() and page_encrypted()
Date: Tue, 6 Mar 2018 17:58:06 +0300	[thread overview]
Message-ID: <20180306145806.ejg5kzaqqmncgqi7@black.fi.intel.com> (raw)
In-Reply-To: <91d27559-3f28-d53c-9fd9-d16e015a3f59@intel.com>

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