From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753555AbeCFNwr (ORCPT ); Tue, 6 Mar 2018 08:52:47 -0500 Received: from mga09.intel.com ([134.134.136.24]:18094 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753075AbeCFNwq (ORCPT ); Tue, 6 Mar 2018 08:52:46 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,431,1515484800"; d="scan'208";a="35016997" Subject: Re: [RFC, PATCH 19/22] x86/mm: Implement free_encrypt_page() To: "Kirill A. Shutemov" References: <20180305162610.37510-1-kirill.shutemov@linux.intel.com> <20180305162610.37510-20-kirill.shutemov@linux.intel.com> <20180306085412.vkgheeya24dze53t@node.shutemov.name> Cc: "Kirill A. Shutemov" , Ingo Molnar , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" , Tom Lendacky , Kai Huang , linux-kernel@vger.kernel.org, linux-mm@kvack.org From: Dave Hansen Message-ID: <64d11e65-76b7-4e70-553c-009263b50a1c@intel.com> Date: Tue, 6 Mar 2018 05:52:44 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180306085412.vkgheeya24dze53t@node.shutemov.name> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/06/2018 12:54 AM, Kirill A. Shutemov wrote: >> Have you measured how slow this is? > No, I have not. It would be handy to do this. I *think* you can do it on normal hardware, even if it does not have "real" support for memory encryption. Just don't set the encryption bits in the PTEs but go through all the motions of cache flushing. I think that will help tell us whether this is a really specialized thing a la hugetlbfs or whether it's something we really want to support as a first-class citizen in the VM.