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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3322EC31E40 for ; Mon, 12 Aug 2019 12:15:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1235620651 for ; Mon, 12 Aug 2019 12:15:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728459AbfHLMPk (ORCPT ); Mon, 12 Aug 2019 08:15:40 -0400 Received: from verein.lst.de ([213.95.11.211]:47888 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727059AbfHLMPk (ORCPT ); Mon, 12 Aug 2019 08:15:40 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id EC352227A8C; Mon, 12 Aug 2019 14:15:33 +0200 (CEST) Date: Mon, 12 Aug 2019 14:15:32 +0200 From: Christoph Hellwig To: "Michael S. Tsirkin" Cc: Christoph Hellwig , Ram Pai , Thiago Jung Bauermann , virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Jason Wang , David Gibson , Alexey Kardashevskiy , Paul Mackerras , Benjamin Herrenschmidt Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Message-ID: <20190812121532.GB9405@lst.de> References: <87zhrj8kcp.fsf@morokweng.localdomain> <20190810143038-mutt-send-email-mst@kernel.org> <20190810220702.GA5964@ram.ibm.com> <20190811055607.GA12488@lst.de> <20190811044431-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190811044431-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 11, 2019 at 04:55:27AM -0400, Michael S. Tsirkin wrote: > On Sun, Aug 11, 2019 at 07:56:07AM +0200, Christoph Hellwig wrote: > > So we need a flag on the virtio device, exposed by the > > hypervisor (or hardware for hw virtio devices) that says: hey, I'm real, > > don't take a shortcut. > > The point here is that it's actually still not real. So we would still > use a physical address. However Linux decides that it wants extra > security by moving all data through the bounce buffer. The distinction > made is that one can actually give device a physical address of the > bounce buffer. Sure. The problem is just that you keep piling hacks on top of hacks. We need the per-device flag anyway to properly support hardware virtio device in all circumstances. Instead of coming up with another ad-hoc hack to force DMA uses implement that one proper bit and reuse it here. 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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 F1A0CC31E40 for ; Mon, 12 Aug 2019 12:15:46 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CCBEE20651 for ; Mon, 12 Aug 2019 12:15:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CCBEE20651 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id D8B1FCC8; Mon, 12 Aug 2019 12:15:40 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id C159DCB2; Mon, 12 Aug 2019 12:15:39 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 5C53D8A0; Mon, 12 Aug 2019 12:15:39 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id EC352227A8C; Mon, 12 Aug 2019 14:15:33 +0200 (CEST) Date: Mon, 12 Aug 2019 14:15:32 +0200 From: Christoph Hellwig To: "Michael S. Tsirkin" Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Message-ID: <20190812121532.GB9405@lst.de> References: <87zhrj8kcp.fsf@morokweng.localdomain> <20190810143038-mutt-send-email-mst@kernel.org> <20190810220702.GA5964@ram.ibm.com> <20190811055607.GA12488@lst.de> <20190811044431-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190811044431-mutt-send-email-mst@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Benjamin Herrenschmidt , Jason Wang , Alexey Kardashevskiy , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Paul Mackerras , iommu@lists.linux-foundation.org, Christoph Hellwig , David Gibson X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Sun, Aug 11, 2019 at 04:55:27AM -0400, Michael S. Tsirkin wrote: > On Sun, Aug 11, 2019 at 07:56:07AM +0200, Christoph Hellwig wrote: > > So we need a flag on the virtio device, exposed by the > > hypervisor (or hardware for hw virtio devices) that says: hey, I'm real, > > don't take a shortcut. > > The point here is that it's actually still not real. So we would still > use a physical address. However Linux decides that it wants extra > security by moving all data through the bounce buffer. The distinction > made is that one can actually give device a physical address of the > bounce buffer. Sure. The problem is just that you keep piling hacks on top of hacks. We need the per-device flag anyway to properly support hardware virtio device in all circumstances. Instead of coming up with another ad-hoc hack to force DMA uses implement that one proper bit and reuse it here. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu