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=-6.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 D764DC11F66 for ; Tue, 13 Jul 2021 00:33:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8791611CB for ; Tue, 13 Jul 2021 00:33:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233759AbhGMAgW (ORCPT ); Mon, 12 Jul 2021 20:36:22 -0400 Received: from mga07.intel.com ([134.134.136.100]:50764 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230099AbhGMAgV (ORCPT ); Mon, 12 Jul 2021 20:36:21 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10043"; a="273907575" X-IronPort-AV: E=Sophos;i="5.84,235,1620716400"; d="scan'208";a="273907575" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2021 17:33:29 -0700 X-IronPort-AV: E=Sophos;i="5.84,235,1620716400"; d="scan'208";a="629866664" Received: from atton-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.212.86.233]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2021 17:33:28 -0700 Subject: Re: [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver To: Andi Kleen , Dave Hansen , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Hans de Goede , Mark Gross , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Peter H Anvin , Tony Luck , Dan Williams , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , x86@kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org References: <20210707204249.3046665-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210707204249.3046665-6-sathyanarayanan.kuppuswamy@linux.intel.com> <06c85c19-e16c-3121-ed47-075cfa779b67@kernel.org> <169451ef-e8f6-5a07-f47a-61eaa085b4ef@intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: Date: Mon, 12 Jul 2021 17:33:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Dave, On 7/8/21 5:38 PM, Andi Kleen wrote: >> Expensive and permanently fractures the direct map. >> >> I'm struggling to figure out why the direct map is even touched here. > I think Sathya did it this way because the TD interface requires a physical address. >> Why not just use a vmalloc area mapping?  You really just need *a* >> decrypted mapping to the page.  You don't need to make *every* mapping >> to the page decrypted. > > Yes it would be possible to use vmap() on the page and only set the vmap encrypted by passing the > right flags directly. Is it alright to have non coherent mappings? If yes, any documentation reference for it? > > That would avoid breaking up the direct mapping. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer