Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCHv3 1/3] x86/mm/encrypt: Move page table helpers into
 separate translation unit
To:     "Kirill A. Shutemov" <kirill@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>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@suse.de>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <20180124163623.61765-1-kirill.shutemov@linux.intel.com>
 <20180124163623.61765-2-kirill.shutemov@linux.intel.com>
 <f1005ed5-c245-b64f-fe4b-64fff5790172@amd.com>
 <20180130222800.7hrnzpy56fb6jwnn@node.shutemov.name>
From:   Tom Lendacky <thomas.lendacky@amd.com>
Message-ID: <e35bd204-a8d5-f88b-c042-c9eca792493a@amd.com>
Date:   Tue, 30 Jan 2018 16:40:16 -0600
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.5.2
MIME-Version: 1.0
In-Reply-To: <20180130222800.7hrnzpy56fb6jwnn@node.shutemov.name>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Received-SPF: None (protection.outlook.com: amd.com does not designate
 permitted sender hosts)
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jan 2018 22:40:21.1073 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: d8faab49-f626-4c89-95ac-08d5683272a0
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR12MB1143
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 1/30/2018 4:28 PM, Kirill A. Shutemov wrote:
> On Tue, Jan 30, 2018 at 04:26:03PM -0600, Tom Lendacky wrote:
>> On 1/24/2018 10:36 AM, Kirill A. Shutemov wrote:
>>> There are bunch of functions in mem_encrypt.c that operate on the
>>> identity mapping, which means they want virtual addresses to be equal to
>>> physical one, without PAGE_OFFSET shift.
>>>
>>> We also need to avoid paravirtualizaion call there.
>>>
>>> Getting this done is tricky. We cannot use usual page table helpers.
>>> It forces us to open-code a lot of things. It makes code ugly and hard
>>> to modify.
>>>
>>> We can get it work with the page table helpers, but it requires few
>>> preprocessor tricks. These tricks may have side effects for the rest of
>>> the file.
>>>
>>> Let's isolate such functions into own translation unit.
>>>
>>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>>
>> Just one minor comment at the end.  With that change:
>>
>> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
>>
>>> ---
>>>  arch/x86/mm/Makefile               |  14 +-
>>>  arch/x86/mm/mem_encrypt.c          | 578 +----------------------------------
>>>  arch/x86/mm/mem_encrypt_identity.c | 596 +++++++++++++++++++++++++++++++++++++
>>>  arch/x86/mm/mm_internal.h          |   1 +
>>>  4 files changed, 607 insertions(+), 582 deletions(-)
>>>  create mode 100644 arch/x86/mm/mem_encrypt_identity.c
>>>
>>
>> ...
>>
>>> diff --git a/arch/x86/mm/mm_internal.h b/arch/x86/mm/mm_internal.h
>>> index 4e1f6e1b8159..7b4fc4386d90 100644
>>> --- a/arch/x86/mm/mm_internal.h
>>> +++ b/arch/x86/mm/mm_internal.h
>>> @@ -19,4 +19,5 @@ extern int after_bootmem;
>>>  
>>>  void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache);
>>>  
>>> +extern bool sev_enabled __section(.data);
>>
>> Lets move this into arch/x86/include/asm/mem_encrypt.h and then add
>> #include <linux/mem_encrypt.h> to mem_encrypt_identity.c.
> 
> Why? Will we need it beyond arch/x86/mm/ in the future?

I just think it would be best to keep all the memory encryption stuff
together.

Thanks,
Tom

>