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 D5DD4C433EF for ; Fri, 22 Jul 2022 21:19:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233627AbiGVVTC (ORCPT ); Fri, 22 Jul 2022 17:19:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229522AbiGVVTA (ORCPT ); Fri, 22 Jul 2022 17:19:00 -0400 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7B5681496 for ; Fri, 22 Jul 2022 14:18:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1658524739; x=1690060739; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=JNEVeaQpNIkYZAQkbOrI2gpmynzCWz40l3qhi8iEsRE=; b=UbMRaaza35Bw5ubQVD7drpUvNxYYG8JUOolBnBM4Z5CO1XRCavYB2Ny8 355+RDvU02vtpruOJuiPTi/9GfNGjRfGEqq3C6YfGa9KfQLX8PyYNIEJ3 77LkSDXh+tjlI4F1gXUtUJpWvjc6Nx9wWoEV+8NbkS1l6oUQyOgcETutd 4HwQTe8BFYnb2UNVe9z7i5USuen2C30NXCCWWEs53MQ1J0Kt2YWXvlA9H UzUvVybtNkVWMYn6nPFDovDk31qU/Jr5yFJ2hUMULzcadyHzxNozS1Gie mSyUkzgVQ1y8lhuvuVWAXs1l2a/G/GoJVaEuUgK1J4GyFaoWURvguQtgh g==; X-IronPort-AV: E=McAfee;i="6400,9594,10416"; a="267802562" X-IronPort-AV: E=Sophos;i="5.93,186,1654585200"; d="scan'208";a="267802562" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2022 14:18:59 -0700 X-IronPort-AV: E=Sophos;i="5.93,186,1654585200"; d="scan'208";a="574311344" Received: from atsunori-mobl1.amr.corp.intel.com (HELO [10.251.22.108]) ([10.251.22.108]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2022 14:18:58 -0700 Message-ID: Date: Fri, 22 Jul 2022 14:18:58 -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 v8 5/5] x86/tdx: Add Quote generation support Content-Language: en-US To: Dave Hansen , Isaku Yamahata Cc: 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, "Nakajima, Jun" References: <20220609025220.2615197-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20220609025220.2615197-6-sathyanarayanan.kuppuswamy@linux.intel.com> <403cfccb-7fff-ab0b-8ebd-e5b04e631571@intel.com> <20220722190524.GA3299911@ls.amr.corp.intel.com> <18578c5a-7a35-ab20-467c-80141b0410a8@intel.com> From: Sathyanarayanan Kuppuswamy In-Reply-To: <18578c5a-7a35-ab20-467c-80141b0410a8@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org + Jun On 7/22/22 12:13 PM, Dave Hansen wrote: > On 7/22/22 12:05, Isaku Yamahata wrote: >>> So, the quote portion of this is basically a bidirectional blob sender. >>> It's to send a blob between guest userspace to host userspace. >>> >>> Do we *REALLY* need specific driver functionality for this? For >>> instance, is there no existing virtio device that can send blobs back >>> and forth? >> It's virtio-vsock. If virtio-vsock is available, the communication works. >> However, some users would like to disable virtio-vsock on their environment for >> some reasons. Even virtio at all. Especially for confidential computing use >> case. It's their choice. It can't be assumed that virtio is available. >> >> The goal is VMM-agnostic (but TDX-specific) interface for that. > > You're basically saying that every confidential computing technology > should have its own host user <-> guest kernel <-> guest user ABI. > That's insanity. If we do this, we need *one* interface that says "talk > to the hypervisor" that's common for all hypervisors and hardware > vendors, or at least more than *one*. > > We don't need a way to talk to hypervisors for Intel systems and another > for AMD and yet another on whatever. For cases where your platform does not want to support or enable the generic interface (like vsock), isn't it better to have a fallback approach? I am not saying we should have such an ABI for all cases. But attestation is a must-have feature for the TDX guest, and we want to support it in all TD guest platforms. I think the GHCI ABI is added to meet this requirement. Jun/Isaku, if you are aware of the exact requirement for this hypercall, please share it. Also let us know your comments on this topic. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer