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 1082FC6FA89 for ; Thu, 15 Sep 2022 00:30:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229601AbiIOAau (ORCPT ); Wed, 14 Sep 2022 20:30:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbiIOAat (ORCPT ); Wed, 14 Sep 2022 20:30:49 -0400 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E53D886FF7; Wed, 14 Sep 2022 17:30:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663201848; x=1694737848; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=f3arqoM1mTN79PR584P6N+hqC5q/kwp/eTlHzWZFjgw=; b=nu+7lIo2ischnxQEON7BpILh6o9oA8NALaem6kJUdoIX1d5qlu4NRQGV BeDKghTR0Vq8gvIlnC0utiAlRWZ4yISYUdEZe7FXcSIeJioxRgl95R+KJ Cxfxq0ASnI6Il9iRx8gu4LrReBADKTzDh41zK9UIvQkSIi9ZS1C0SzD2D eD6RQBvbqCXV4OXhJ1c3pVFqnJoAUgVbuc4AOyGgEfJGgn2GAJSH85eO9 UMYgdFSRM05V4pKS70rf8VzyVrs2nekVFWapND0vzs20Kf2wuH/Ir+Dqo ewIqUUEIHqZBJxJnsq6oso0UUQ9r/nisb+6iyX9+BvzUh+4adjrGNT1I4 Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10470"; a="362536145" X-IronPort-AV: E=Sophos;i="5.93,316,1654585200"; d="scan'208";a="362536145" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Sep 2022 17:30:47 -0700 X-IronPort-AV: E=Sophos;i="5.93,316,1654585200"; d="scan'208";a="759418141" Received: from mmcgoort-mobl.amr.corp.intel.com (HELO [10.209.54.54]) ([10.209.54.54]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Sep 2022 17:30:46 -0700 Message-ID: Date: Wed, 14 Sep 2022 17:30:45 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.11.0 Subject: Re: [PATCH v13 1/3] x86/tdx: Add TDX Guest attestation interface driver Content-Language: en-US To: Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Shuah Khan Cc: "H . Peter Anvin" , Greg Kroah-Hartman , "Kirill A . Shutemov" , Tony Luck , Andi Kleen , Kai Huang , Wander Lairson Costa , Isaku Yamahata , marcelo.cerri@canonical.com, tim.gardner@canonical.com, khalid.elmously@canonical.com, philip.cox@canonical.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org References: <20220909192708.1113126-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20220909192708.1113126-2-sathyanarayanan.kuppuswamy@linux.intel.com> <7c3cc265-869b-b2fc-43f2-d2cbd0bc142c@intel.com> <1182ef92-cae3-b7c1-8339-8e8bfa48f2e3@linux.intel.com> From: Sathyanarayanan Kuppuswamy In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 9/14/22 9:12 AM, Dave Hansen wrote: > On 9/14/22 08:36, Sathyanarayanan Kuppuswamy wrote: >> When we initially submitted the attestation patches, virt/coco folder >> was not created. I initially kept this driver in platform/x86/, but >> later moved to arch/x86/coco based on the review comments in v4. There >> was a discussion about the need for a new config and the location of >> the driver. The outcome of that discussion is, since this is not a >> traditional driver, but a basic TDX feature, we don't need a special >> config and the code can be maintained in the arch/x86/coco folder. > > Could you please include the following in this set somewhere: > > "The code to do the SEV analog of this TDX functionality is in > ___insert_path_here____. This code is different from that because > ______reason______ so it is instead placed in ____other_path____." > > ? I have also included info about why we don't use a separate config option for it. The code for the SEV equivalent of this TDX attestation functionality can be found in drivers/virt/coco/sev-guest/. It is implemented as a platform module driver, and it can be enabled using the CONFIG_SEV_GUEST config option. However, in the case of TDX, it is implemented as a built-in driver in the arch/x86/coco/tdx/tdx.c because of the following reasons: 1. Attestation is expected to be needed by all distributions that support TDX. Therefore, using a separate configuration option is not necessary. With TDX support, it can be enabled by default, and a built-in driver model will work better in this use case. 2. Since it is not a conventional device driver and the code is very simple, creating an individual driver for it may be an overkill. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer