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 AD9FAC433EF for ; Thu, 21 Jul 2022 18:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231374AbiGUSw3 (ORCPT ); Thu, 21 Jul 2022 14:52:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229379AbiGUSw2 (ORCPT ); Thu, 21 Jul 2022 14:52:28 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B19842ED5A for ; Thu, 21 Jul 2022 11:52:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1658429546; x=1689965546; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=BWL7+RtnFnoXytr6NeetuBR2+uRW0R2T7TZSH0tDrAg=; b=nnnfm1yzT2N/Un2tDiHOcAccVE78hZ/zZr/zIjQsR2wBFfHIEg6pgIjo htyaSr35I72NmVtBwU+kgUwecv4AlPgtNa8IrOOdoqOigptlPAOo/Aqvb nc6NyAv9luMeMcKlz4zO3lLmQRXRWELj3BwaTCZzooOsNf6yfpX6Rkcsc JBabxKAXqljSOK1fCXmogrj4eBpxLsw2v9mpWbj3koDJOgnW06nHSb1vB 8aUzGtKYzuB374kjW4wtrruGKauBAxL8XdJsUTAOS6ilsC6vxX/rDeDHu Q2FpVj8T81eiV5yQH/gYQAhgXGXjhAYj79QC4ZAH9aaDGTUxqEjUu+SoU w==; X-IronPort-AV: E=McAfee;i="6400,9594,10415"; a="273998501" X-IronPort-AV: E=Sophos;i="5.93,183,1654585200"; d="scan'208";a="273998501" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2022 11:52:26 -0700 X-IronPort-AV: E=Sophos;i="5.93,183,1654585200"; d="scan'208";a="573867059" Received: from vasantgx-mobl.amr.corp.intel.com (HELO [10.212.244.191]) ([10.212.244.191]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2022 11:52:25 -0700 Message-ID: <1fdecc17-8f4f-fceb-8da0-4a21ca0d58be@intel.com> Date: Thu, 21 Jul 2022 11:52:24 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v8 5/5] x86/tdx: Add Quote generation support Content-Language: en-US To: Isaku Yamahata Cc: Sathyanarayanan Kuppuswamy , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , "Kirill A . Shutemov" , Tony Luck , Andi Kleen , Kai Huang , Wander Lairson Costa , marcelo.cerri@canonical.com, tim.gardner@canonical.com, khalid.elmously@canonical.com, philip.cox@canonical.com, linux-kernel@vger.kernel.org References: <20220609025220.2615197-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20220609025220.2615197-6-sathyanarayanan.kuppuswamy@linux.intel.com> <214e24f0-5236-be8d-024a-da48737d854a@intel.com> <20220721184221.GA3288872@ls.amr.corp.intel.com> From: Dave Hansen In-Reply-To: <20220721184221.GA3288872@ls.amr.corp.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 7/21/22 11:42, Isaku Yamahata wrote: > Regarding to the size of quote, there is no hard limit because it's for future > usage. But here is a rough idea about it. > > - 4KB(1 page) can accommodate TDREPORT that is defined right now. > - 128KB is too small for foreseen use cases. > - 1MB is too big. big enough for future. Again, we're off in the weeds. How does the VMM know how much to read/write? I have a theory: the spec says that R12 is: "Shared 4KB GPA as input – the memory contains a TDREPORT_STRUCT." That's *A* 4KB GPA. The maximum is one 4KB page. That's the only thing that makes sense because there's no length in the ABI anywhere. What am I missing?