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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D0F90C43381 for ; Mon, 25 Feb 2019 22:24:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CE01217F5 for ; Mon, 25 Feb 2019 22:24:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="XDC0lB4o" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727149AbfBYWY4 (ORCPT ); Mon, 25 Feb 2019 17:24:56 -0500 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:57252 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726919AbfBYWY4 (ORCPT ); Mon, 25 Feb 2019 17:24:56 -0500 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 8A9128EE1A0; Mon, 25 Feb 2019 14:24:55 -0800 (PST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id b1FCeoJGUl5q; Mon, 25 Feb 2019 14:24:55 -0800 (PST) Received: from [153.66.254.194] (unknown [50.35.68.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 209998EE101; Mon, 25 Feb 2019 14:24:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1551133494; bh=gYPCkZ9FZitooDGmvyYgKnn+jkl/V8/CrR0hwnaMTFs=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=XDC0lB4oub4kFkJ/JtseRC3wcnQ8zzcltSVe+RbZEWDWMcVL7JZfxJQDO+C3ggoKL UTg0eiC4GaJ62sRybwd3mtiEAde/QqMZNFS+Cf5vzFwVZqTsi0jamkhA4E0fVcNGGd kcfgru8/6LyGD1JaFFiJWYDExlyhNBXHpqKHVW9Q= Message-ID: <1551133491.3226.75.camel@HansenPartnership.com> Subject: Re: [PATCH] tpm: Add driver for TPM over virtio From: James Bottomley To: Jarkko Sakkinen Cc: Matthew Garrett , David Tolnay , Peter Huewe , Jason Gunthorpe , linux-integrity , "Michael S. Tsirkin" , Jason Wang , virtualization@lists.linux-foundation.org, dgreid@chromium.org, apronin@chromium.org Date: Mon, 25 Feb 2019 14:24:51 -0800 In-Reply-To: <20190225210511.GA8727@linux.intel.com> References: <1550873900.2787.25.camel@HansenPartnership.com> <1550885645.3577.31.camel@HansenPartnership.com> <1551025819.3106.25.camel@HansenPartnership.com> <1551108969.3226.26.camel@HansenPartnership.com> <1551126043.3226.45.camel@HansenPartnership.com> <20190225210511.GA8727@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, 2019-02-25 at 23:05 +0200, Jarkko Sakkinen wrote: > On Mon, Feb 25, 2019 at 12:20:43PM -0800, James Bottomley wrote: > > On Mon, 2019-02-25 at 11:17 -0800, Matthew Garrett wrote: > > > On Mon, Feb 25, 2019 at 7:36 AM James Bottomley > > > wrote: > > > > > The virtio driver performs discovery via virtio, which crosvm > > > > > implements already for all of its supported devices. This > > > > > substantially reduces the amount of TPM-specific code > > > > > compared to your suggestions, and lowers the barrier to entry > > > > > for implementing TPM support in other hypervisors which I > > > > > hope we agree is beneficial. > > > > > > > > Well, that's somewhat misleading: The reason we already have > > > > two hypervisor specific drivers already is because every > > > > hypervisor has a different virtual discovery mechanism. You > > > > didn't find the other two hypervisor drivers remotely useful, > > > > so why would another hypervisor find yours useful? > > > > > > > > > The existing hypervisor drivers expose hypervisor-specific > > > details. This proposed driver provides an abstract interface that > > > is usable by other hypervisors. It allows building a VM that > > > exposes TPM functionality without requiring additional hardware > > > emulation, reducing the hypervisor attack surface. > > > > Well, that depends whether you think a virtio bus is an abstract > > concept or a hypervisor specific detail. There are currently four > > major hypervisors: xen, kvm, hyper-v and ESX. Of those, only one > > implements virtio: kvm. I agree virtio is a standard and certainly > > a slew of minor hypervisors implement it because they need paravirt > > support on Linux so they piggyback off kvm, but I don't see any of > > the other major hypervisors jumping on the bandwagon. > > > > I certainly agree our lives would be easier if all the major > > hypervisor vendors would just agree a single paravirt driver > > standard. > > I think that a Windows hypervisor (Hyper-V) and a closed hypervisor > (VMWare) are out of context for this discussion. But why? We already have both in various Linux subsystems; for instance SCSI has storvsc (hyper-v paravirt storage driver) and vmw_pvscsi (VMWare paravirt storage dirver). The only real requirement is a willingness to open source the driver and publish the communication spec. If another paravirt TPM driver is a good idea, why wouldn't we allow these guys to play in our sandpit too (under the right open source conditions, of course)? James