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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,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 3FA08C04AAF for ; Thu, 16 May 2019 13:54:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A3A420657 for ; Thu, 16 May 2019 13:54:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727642AbfEPNyy (ORCPT ); Thu, 16 May 2019 09:54:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36442 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726769AbfEPNyy (ORCPT ); Thu, 16 May 2019 09:54:54 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E8F4C882FB; Thu, 16 May 2019 13:54:53 +0000 (UTC) Received: from gondolin (dhcp-192-222.str.redhat.com [10.33.192.222]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6CADA60BE5; Thu, 16 May 2019 13:54:46 +0000 (UTC) Date: Thu, 16 May 2019 15:54:44 +0200 From: Cornelia Huck To: Halil Pasic Cc: "Jason J. Herne" , kvm@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky , Sebastian Ott , virtualization@lists.linux-foundation.org, "Michael S. Tsirkin" , Christoph Hellwig , Thomas Huth , Christian Borntraeger , Viktor Mihajlovski , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , Farhan Ali , Eric Farman , Michael Mueller Subject: Re: [PATCH 06/10] s390/cio: add basic protected virtualization support Message-ID: <20190516155444.158867ac.cohuck@redhat.com> In-Reply-To: <20190516154245.4a0a84f7.pasic@linux.ibm.com> References: <20190426183245.37939-1-pasic@linux.ibm.com> <20190426183245.37939-7-pasic@linux.ibm.com> <20190513114136.783c851c.cohuck@redhat.com> <20190515230817.2f8a8a5d.pasic@linux.ibm.com> <20190516083228.0cc5b489.cohuck@redhat.com> <20190516154245.4a0a84f7.pasic@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 16 May 2019 13:54:54 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 16 May 2019 15:42:45 +0200 Halil Pasic wrote: > On Thu, 16 May 2019 08:32:28 +0200 > Cornelia Huck wrote: > > > On Wed, 15 May 2019 23:08:17 +0200 > > Halil Pasic wrote: > > > > > On Tue, 14 May 2019 10:47:34 -0400 > > > "Jason J. Herne" wrote: > > > > > > Are we > > > > worried that virtio data structures are going to be a burden on the 31-bit address space? > > > > > > > > > > > > > > That is a good question I can not answer. Since it is currently at least > > > a page per queue (because we use dma direct, right Mimu?), I am concerned > > > about this. > > > > > > Connie, what is your opinion? > > > > Yes, running into problems there was one of my motivations for my > > question. I guess it depends on the number of devices and how many > > queues they use. The problem is that it affects not only protected virt > > guests, but all guests. > > > > Unless things are about to change only devices that have > VIRTIO_F_IOMMU_PLATFORM are affected. So it does not necessarily affect > not protected virt guests. (With prot virt we have to use > VIRTIO_F_IOMMU_PLATFORM.) > > If it were not like this, I would be much more worried. If we go forward with this approach, documenting this side effect of VIRTIO_F_IOMMU_PLATFORM is something that needs to happen. > > @Mimu: Could you please discuss this problem with the team? It might be > worth considering to go back to the design of the RFC (i.e. cio/ccw stuff > allocated from a common cio dma pool which gives you 31 bit addressable > memory, and 64 bit dma mask for a ccw device of a virtio device). > > Regards, > Halil >