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=-2.4 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 DEA1113F6DFF for ; Mon, 30 Jul 2018 09:34:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FAFC20881 for ; Mon, 30 Jul 2018 09:34:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="lBF9v4+b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7FAFC20881 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727018AbeG3LIY (ORCPT ); Mon, 30 Jul 2018 07:08:24 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:37852 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbeG3LIY (ORCPT ); Mon, 30 Jul 2018 07:08:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=oJ0NUTX86TgKdU19i9RyYhm33mr4nHdA8Q0kxIYlN6E=; b=lBF9v4+bEojlrdIMFsUIndRzG 2m7L+b72NtFMUxSridq3IdmOxUhFPlnBrDjQXQK7CzpBuGfxci0/injq9ea0yk849FWKgBVrzDpjS CbUMYPCrRkR0gnEDGZ5/a9PM49rOTmypzHJvJ7+jeP4oL8g6arWktkjbM47Sju+THnd6XRMtyVXUc Wvmio4f06CesPKwMf8qm9fJvzSEyDIh4l00nEsAvhFzziT6b3HhNMvlqaSdPnbMfMuo0njzBSOx76 SRxucxP6rrv5QIkYIpPco4HtsDN+RiihwArVqal/mebfAehv/6+HaTxXMazwxY8xXulpbTY6d27ja tKuA/0dCA==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1fk4ZC-0003XQ-9Y; Mon, 30 Jul 2018 09:34:14 +0000 Date: Mon, 30 Jul 2018 02:34:14 -0700 From: Christoph Hellwig To: Will Deacon Cc: Anshuman Khandual , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, david@gibson.dropbear.id.au, jasowang@redhat.com, benh@kernel.crashing.org, mpe@ellerman.id.au, mst@redhat.com, hch@infradead.org, linuxram@us.ibm.com, haren@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com, robin.murphy@arm.com, jean-philippe.brucker@arm.com, marc.zyngier@arm.com Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Message-ID: <20180730093414.GD26245@infradead.org> References: <20180720035941.6844-1-khandual@linux.vnet.ibm.com> <20180727095804.GA25592@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180727095804.GA25592@arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 27, 2018 at 10:58:05AM +0100, Will Deacon wrote: > > I just wanted to say that this patch series provides a means for us to > force the coherent DMA ops for legacy virtio devices on arm64, which in turn > means that we can enable the SMMU with legacy devices in our fastmodel > emulation platform (which is slowly being upgraded to virtio 1.0) without > hanging during boot. Patch below. Yikes, this is a nightmare. That is exactly where I do not want things to end up. We really need to distinguish between legacy virtual crappy virtio (and that includes v1) that totally ignores the bus it pretends to be on, and sane virtio (to be defined) that sit on a real (or properly emulated including iommu and details for dma mapping) bus. Having a mumble jumble of arch specific undocumented magic as in the powerpc patch replied to or this arm patch is a complete no-go. Nacked-by: Christoph Hellwig for both. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Date: Mon, 30 Jul 2018 02:34:14 -0700 Message-ID: <20180730093414.GD26245@infradead.org> References: <20180720035941.6844-1-khandual@linux.vnet.ibm.com> <20180727095804.GA25592@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20180727095804.GA25592@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Will Deacon Cc: robh@kernel.org, srikar@linux.vnet.ibm.com, mst@redhat.com, benh@kernel.crashing.org, linuxram@us.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, hch@infradead.org, paulus@samba.org, marc.zyngier@arm.com, mpe@ellerman.id.au, joe@perches.com, robin.murphy@arm.com, david@gibson.dropbear.id.au, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, haren@linux.vnet.ibm.com, Anshuman Khandual List-Id: virtualization@lists.linuxfoundation.org On Fri, Jul 27, 2018 at 10:58:05AM +0100, Will Deacon wrote: > > I just wanted to say that this patch series provides a means for us to > force the coherent DMA ops for legacy virtio devices on arm64, which in turn > means that we can enable the SMMU with legacy devices in our fastmodel > emulation platform (which is slowly being upgraded to virtio 1.0) without > hanging during boot. Patch below. Yikes, this is a nightmare. That is exactly where I do not want things to end up. We really need to distinguish between legacy virtual crappy virtio (and that includes v1) that totally ignores the bus it pretends to be on, and sane virtio (to be defined) that sit on a real (or properly emulated including iommu and details for dma mapping) bus. Having a mumble jumble of arch specific undocumented magic as in the powerpc patch replied to or this arm patch is a complete no-go. Nacked-by: Christoph Hellwig for both.