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Subject: Re: [RFC, PATCH 21/22] x86/mm: Introduce page_keyid() and
 page_encrypted()
To: "Kirill A. Shutemov" <kirill@shutemov.name>
References: <20180305162610.37510-1-kirill.shutemov@linux.intel.com>
 <20180305162610.37510-22-kirill.shutemov@linux.intel.com>
 <61041640-435e-1a67-177f-a75791130514@intel.com>
 <20180306085751.tvozsfe6hogh37pd@node.shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        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
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <91d27559-3f28-d53c-9fd9-d16e015a3f59@intel.com>
Date: Tue, 6 Mar 2018 06:56:08 -0800
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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?"