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[79.181.91.42]) by smtp.gmail.com with ESMTPSA id x26sm3314318qkn.116.2019.08.11.01.55.29 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sun, 11 Aug 2019 01:55:33 -0700 (PDT) Date: Sun, 11 Aug 2019 04:55:27 -0400 From: "Michael S. Tsirkin" To: Christoph Hellwig Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Message-ID: <20190811044431-mutt-send-email-mst@kernel.org> References: <87zhrj8kcp.fsf@morokweng.localdomain> <20190810143038-mutt-send-email-mst@kernel.org> <20190810220702.GA5964@ram.ibm.com> <20190811055607.GA12488@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190811055607.GA12488@lst.de> 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, 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 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. -- MST _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 13E7DC0650F for ; Sun, 11 Aug 2019 08:55:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE764208C2 for ; Sun, 11 Aug 2019 08:55:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726075AbfHKIzf (ORCPT ); Sun, 11 Aug 2019 04:55:35 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:42704 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725776AbfHKIzf (ORCPT ); Sun, 11 Aug 2019 04:55:35 -0400 Received: by mail-qt1-f195.google.com with SMTP id t12so11449697qtp.9 for ; Sun, 11 Aug 2019 01:55:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6/2qVAPvLy768Na8XqJHyfaQBOmu1VTQjHr1b0tqDos=; b=ZK247MQpGCfiPlj4HG6le8S9ob6xibKINExrP3oS+KUneAUryU7xK3+tF1N8P0FZVf BqyOGWQF9I5/pnm6NTpx1faSyZ5lc9v/y4xnJWY87QUORzsTpyI53b3XwhSWq/hZ4gzi JtFZ0ikk15BxYxH0K9BW5AqjejqNmIGIUYvSjW+uB7E71URijMzAJiFbIoeWWkq4P13f VDIA7adhkxRnDcrn1kd5le+8APImHyeyyA7luKMW8OS9FfIMMv+Xh7B7tRG/+2k4trT8 a2c21qsgl7agovqPdmH4FgYExxE/1tO8NHXEGG6CivE3Vz0C2xyjO52wgwUwYwqrHgMV TteA== X-Gm-Message-State: APjAAAVffyV1zs9UAC61FL0xCBxjKQIrvbaft9hLwqZtgL6S3gS2VxZK A1v1DtyfNsZO4+BULr6jPLnnJw== X-Google-Smtp-Source: APXvYqwQSHWl5DZCKxcv6b09e+m/U60yeBUP2tSK+Zxbso+cleqVM/RZ1b43sqdRDBiAuYOyKuC1mA== X-Received: by 2002:a0c:d91b:: with SMTP id p27mr25451190qvj.236.1565513734175; Sun, 11 Aug 2019 01:55:34 -0700 (PDT) Received: from redhat.com (bzq-79-181-91-42.red.bezeqint.net. [79.181.91.42]) by smtp.gmail.com with ESMTPSA id x26sm3314318qkn.116.2019.08.11.01.55.29 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sun, 11 Aug 2019 01:55:33 -0700 (PDT) Date: Sun, 11 Aug 2019 04:55:27 -0400 From: "Michael S. Tsirkin" To: Christoph Hellwig Cc: 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: <20190811044431-mutt-send-email-mst@kernel.org> References: <87zhrj8kcp.fsf@morokweng.localdomain> <20190810143038-mutt-send-email-mst@kernel.org> <20190810220702.GA5964@ram.ibm.com> <20190811055607.GA12488@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190811055607.GA12488@lst.de> 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 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. -- MST