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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 977CFC433F5 for ; Tue, 19 Apr 2022 14:26:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353289AbiDSO3D (ORCPT ); Tue, 19 Apr 2022 10:29:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349562AbiDSO11 (ORCPT ); Tue, 19 Apr 2022 10:27:27 -0400 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CB5835A86; Tue, 19 Apr 2022 07:24:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650378285; x=1681914285; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=S/AnCfZB2POHJ489DdjypzBOnhx3vZSBUI8TEc0qIJI=; b=CqPZLWOe+A78Wk+FwsEcLBVERF48br7drCngxW6KoCRdoVhqGzDLhbtb PG/eI5Gs6TVWfli+/eZ2Tdrr5rn7VD4CTH/THi54vaftjOLagxXJ31Tk0 XS5NySOFQtHcTcoQ6GaOc+C9cwLb1hN61UHVtXJHLkBubYaLJ+co1J5c0 rbIy9SGIrmCFO00zISvMOf6lsE4rrBt0Bw0aI4qNSLEBFT05+8KrV0sHc Iaxv4o3sDiLV7AjuRq0azNksRXAK4Ag0cGNjl2VY7PB4dcdrqu4Qglqa9 QqeI7/YxNXGwgJkgsbpN5cL1SEVBg6eli7lpvvALPYV3R85vSqEe020NC Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10322"; a="324219231" X-IronPort-AV: E=Sophos;i="5.90,272,1643702400"; d="scan'208";a="324219231" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Apr 2022 07:24:44 -0700 X-IronPort-AV: E=Sophos;i="5.90,272,1643702400"; d="scan'208";a="657656324" Received: from aislaslo-mobl.amr.corp.intel.com (HELO [10.212.57.245]) ([10.212.57.245]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Apr 2022 07:24:43 -0700 Message-ID: <72205a7a-faf2-4322-02cd-303ee8252abb@intel.com> Date: Tue, 19 Apr 2022 07:24:43 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Content-Language: en-US To: Sathyanarayanan Kuppuswamy , Kai Huang , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Hans de Goede , Mark Gross Cc: "H . Peter Anvin" , "Kirill A . Shutemov" , Tony Luck , Andi Kleen , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org References: <20220415220109.282834-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20220415220109.282834-5-sathyanarayanan.kuppuswamy@linux.intel.com> <975b5050-2108-9ace-cc71-46f17db0a731@intel.com> <4875ea9c-593a-e669-889a-1e809a50a570@linux.intel.com> From: Dave Hansen Subject: Re: [PATCH v3 4/4] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver In-Reply-To: <4875ea9c-593a-e669-889a-1e809a50a570@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/19/22 07:19, Sathyanarayanan Kuppuswamy wrote: > On 4/19/22 7:13 AM, Dave Hansen wrote: >>> >From this perspective, I am not sure what's the value of having a >>> dedicated >>> INTEL_TDX_ATTESTATION Kconfig.  The attestation support code should >>> be turned on >>> unconditionally when CONFIG_INTEL_TDX_GUEST is on.  The code can also >>> be just >>> under arch/x86/coco/tdx/ I guess? >> How much code are we talking about?  What's the difference in the size >> of the binaries with this compiled in? > > Current driver size is ~300 lines. It adds ~500 bytes to the kernel > binary if it is built-in. That doesn't sound like good use of a Kconfig option to me. Just explain in the cover letter: Any distribution enabling TDX is also expected to need attestation. The compiled size is quite small (500 bytes).