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

[Andy Lutomirski]

On Wed, Apr 27, 2016 at 7:44 AM, Tom Lendacky <thomas.lendacky@xxxxxxx> wrote:
> On 04/27/2016 09:33 AM, Andy Lutomirski wrote:
>> On Tue, Apr 26, 2016 at 3:56 PM, Tom Lendacky <thomas.lendacky@xxxxxxx> 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.

--Andy