From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43E4CC4320A for ; Tue, 10 Aug 2021 19:09:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D00BA6109F for ; Tue, 10 Aug 2021 19:08:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D00BA6109F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 1ECF48D0001; Tue, 10 Aug 2021 15:08:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 19D6B6B0072; Tue, 10 Aug 2021 15:08:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 08C378D0001; Tue, 10 Aug 2021 15:08:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id E0C826B0071 for ; Tue, 10 Aug 2021 15:08:58 -0400 (EDT) Received: from smtpin34.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 63F1F19227 for ; Tue, 10 Aug 2021 19:08:58 +0000 (UTC) X-FDA: 78460108356.34.311A4B5 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by imf28.hostedemail.com (Postfix) with ESMTP id 5E8BA9009F0D for ; Tue, 10 Aug 2021 19:08:57 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10072"; a="278721127" X-IronPort-AV: E=Sophos;i="5.84,310,1620716400"; d="scan'208";a="278721127" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Aug 2021 12:08:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,310,1620716400"; d="scan'208";a="460504963" Received: from black.fi.intel.com ([10.237.72.28]) by orsmga007.jf.intel.com with ESMTP; 10 Aug 2021 12:08:49 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 3F085F9; Tue, 10 Aug 2021 22:08:36 +0300 (EEST) Date: Tue, 10 Aug 2021 22:08:36 +0300 From: "Kirill A. Shutemov" To: Dave Hansen Cc: "Kirill A. Shutemov" , Borislav Petkov , Andy Lutomirski , Sean Christopherson , Andrew Morton , Joerg Roedel , Andi Kleen , Kuppuswamy Sathyanarayanan , David Rientjes , Vlastimil Babka , Tom Lendacky , Thomas Gleixner , Peter Zijlstra , Paolo Bonzini , Ingo Molnar , Varad Gautam , Dario Faggioli , x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/5] efi/x86: Implement support for unaccepted memory Message-ID: <20210810190836.cffj4fjqenuunwsd@black.fi.intel.com> References: <20210810062626.1012-1-kirill.shutemov@linux.intel.com> <20210810062626.1012-3-kirill.shutemov@linux.intel.com> <07c2770e-1171-24ab-9403-91b306b5b1a4@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <07c2770e-1171-24ab-9403-91b306b5b1a4@intel.com> Authentication-Results: imf28.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf28.hostedemail.com: domain of kirill.shutemov@linux.intel.com has no SPF policy when checking 134.134.136.100) smtp.mailfrom=kirill.shutemov@linux.intel.com X-Stat-Signature: tfzka6x7gd8hg1wn945dixgzhsocrcdt X-Rspamd-Queue-Id: 5E8BA9009F0D X-Rspamd-Server: rspam01 X-HE-Tag: 1628622537-432284 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 10, 2021 at 11:30:42AM -0700, Dave Hansen wrote: > On 8/9/21 11:26 PM, Kirill A. Shutemov wrote: > > +config UNACCEPTED_MEMORY > > + bool > > + depends on EFI_STUB > > + help > > + Some Virtual Machine platforms, such as Intel TDX, introduce > > + the concept of memory acceptance, requiring memory to be accepted > > + before it can be used by the guest. This protects against a class of > > + attacks by the virtual machine platform. > > + > > + This option adds support for unaccepted memory and makes such memory > > + usable by kernel. > > Do we really need a full-blown user-visible option here? If we, for > instance, just did: > > config UNACCEPTED_MEMORY > bool > depends on EFI_STUB > > it could be 'select'ed from the TDX Kconfig and no users would ever be > bothered with it. Would a user *ever* turn this on if they don't have > TDX (or equivalent)? But it's already not user selectable. Note that there's no prompt next to the "bool". The "help" section is just for documentation. I think it can be useful. -- Kirill A. Shutemov