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 C0814C10F14 for ; Tue, 15 Oct 2019 07:37:27 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 6EC0C2086A for ; Tue, 15 Oct 2019 07:37:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EC0C2086A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 46snM91r9YzDqfs for ; Tue, 15 Oct 2019 18:37:25 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 46snJZ04WHzDq8X for ; Tue, 15 Oct 2019 18:35:10 +1100 (AEDT) Received: by verein.lst.de (Postfix, from userid 2407) id 4C96D68CEE; Tue, 15 Oct 2019 09:35:02 +0200 (CEST) Date: Tue, 15 Oct 2019 09:35:01 +0200 From: Christoph Hellwig To: Ram Pai Subject: Re: [PATCH 2/2] virtio_ring: Use DMA API if memory is encrypted Message-ID: <20191015073501.GA32345@lst.de> References: <1570843519-8696-1-git-send-email-linuxram@us.ibm.com> <1570843519-8696-2-git-send-email-linuxram@us.ibm.com> <1570843519-8696-3-git-send-email-linuxram@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1570843519-8696-3-git-send-email-linuxram@us.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: andmike@us.ibm.com, sukadev@linux.vnet.ibm.com, mdroth@linux.vnet.ibm.com, b.zolnierkie@samsung.com, jasowang@redhat.com, aik@linux.ibm.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, paul.burton@mips.com, robin.murphy@arm.com, m.szyprowski@samsung.com, linuxppc-dev@lists.ozlabs.org, hch@lst.de, david@gibson.dropbear.id.au Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Oct 11, 2019 at 06:25:19PM -0700, Ram Pai wrote: > From: Thiago Jung Bauermann > > Normally, virtio enables DMA API with VIRTIO_F_IOMMU_PLATFORM, which must > be set by both device and guest driver. However, as a hack, when DMA API > returns physical addresses, guest driver can use the DMA API; even though > device does not set VIRTIO_F_IOMMU_PLATFORM and just uses physical > addresses. Sorry, but this is a complete bullshit hack. Driver must always use the DMA API if they do DMA, and if virtio devices use physical addresses that needs to be returned through the platform firmware interfaces for the dma setup. If you don't do that yet (which based on previous informations you don't), you need to fix it, and we can then quirk old implementations that already are out in the field. In other words: we finally need to fix that virtio mess and not pile hacks on top of hacks.