linux-kernel - Re: [RFC PATCH v1 01/18] x86: Set the write-protect cache mode for AMD processors

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Date:	Wed, 27 Apr 2016 10:05:42 -0500
From:	Tom Lendacky <thomas.lendacky@....com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	linux-arch <linux-arch@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
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	Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [RFC PATCH v1 01/18] x86: Set the write-protect cache mode for
 AMD processors

On 04/27/2016 09:47 AM, Andy Lutomirski wrote:
> On Wed, Apr 27, 2016 at 7:44 AM, Tom Lendacky <thomas.lendacky@....com> wrote:
>> On 04/27/2016 09:33 AM, Andy Lutomirski wrote:
>>> On Tue, Apr 26, 2016 at 3:56 PM, Tom Lendacky <thomas.lendacky@....com> wrote:
>>>> For AMD processors that support PAT, set the write-protect cache mode
>>>> (_PAGE_CACHE_MODE_WP) entry to the actual write-protect value (x05).
>>>
>>> What's the purpose of using the WP memory type?
>>
>> The WP memory type is used for encrypting or decrypting data "in place".
>> The use of the WP on the source data will prevent any of the source
>> data from being cached.  Refer to section 7.10.8 "Encrypt-in-Place" in
>> the AMD64 APM link provided in the cover letter.
>>
>> This memory type will be used in subsequent patches for this purpose.
> 
> OK.
> 
> Why AMD-only?  I thought Intel supported WP, too.

Just me being conservative. If there aren't any objections from the
Intel folks about it we can remove the vendor check and just set it.

Thanks,
Tom

> 
> --Andy
>