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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 6D92BC11D0B for ; Thu, 20 Feb 2020 16:13:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 41C0A20658 for ; Thu, 20 Feb 2020 16:13:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728607AbgBTQNM (ORCPT ); Thu, 20 Feb 2020 11:13:12 -0500 Received: from verein.lst.de ([213.95.11.211]:50190 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727233AbgBTQNM (ORCPT ); Thu, 20 Feb 2020 11:13:12 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 02BC668BFE; Thu, 20 Feb 2020 17:13:10 +0100 (CET) Date: Thu, 20 Feb 2020 17:13:09 +0100 From: Christoph Hellwig To: Halil Pasic Cc: "Michael S. Tsirkin" , Jason Wang , Marek Szyprowski , Robin Murphy , Christoph Hellwig , linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Christian Borntraeger , Janosch Frank , Viktor Mihajlovski , Cornelia Huck , Ram Pai , Thiago Jung Bauermann , David Gibson , "Lendacky, Thomas" , Michael Mueller Subject: Re: [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected Message-ID: <20200220161309.GB12709@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-3-pasic@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200220160606.53156-3-pasic@linux.ibm.com> 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 Thu, Feb 20, 2020 at 05:06:06PM +0100, Halil Pasic wrote: > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 867c7ebd3f10..fafc8f924955 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -243,6 +243,9 @@ static bool vring_use_dma_api(struct virtio_device *vdev) > if (!virtio_has_iommu_quirk(vdev)) > return true; > > + if (force_dma_unencrypted(&vdev->dev)) > + return true; Hell no. This is a detail of the platform DMA direct implementation. Drivers have no business looking at this flag, and virtio finally needs to be fixed to use the DMA API properly for everything but legacy devices. No amount of desparate hacks is going to fix that fundamental problem, and I'm starting to get really sick and tired of all the crap patches published in this area. 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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 07DABC11D05 for ; Thu, 20 Feb 2020 16:13:17 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 DA31820659 for ; Thu, 20 Feb 2020 16:13:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA31820659 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 localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 7F1C38796C; Thu, 20 Feb 2020 16:13:16 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id K0u4oI84NEsw; Thu, 20 Feb 2020 16:13:15 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 11FBB87AA1; Thu, 20 Feb 2020 16:13:15 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id F3A1DC1D81; Thu, 20 Feb 2020 16:13:14 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0D06CC013E; Thu, 20 Feb 2020 16:13:14 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id EAF1E203E7; Thu, 20 Feb 2020 16:13:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id uMWRz4x787zu; Thu, 20 Feb 2020 16:13:12 +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 silver.osuosl.org (Postfix) with ESMTPS id 78BE0203B9; Thu, 20 Feb 2020 16:13:12 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 02BC668BFE; Thu, 20 Feb 2020 17:13:10 +0100 (CET) Date: Thu, 20 Feb 2020 17:13:09 +0100 From: Christoph Hellwig To: Halil Pasic Subject: Re: [PATCH 2/2] virtio: let virtio use DMA API when guest RAM is protected Message-ID: <20200220161309.GB12709@lst.de> References: <20200220160606.53156-1-pasic@linux.ibm.com> <20200220160606.53156-3-pasic@linux.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200220160606.53156-3-pasic@linux.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-s390@vger.kernel.org, Janosch Frank , "Michael S. Tsirkin" , Jason Wang , Cornelia Huck , Ram Pai , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Christian Borntraeger , iommu@lists.linux-foundation.org, David Gibson , Michael Mueller , "Lendacky, Thomas" , Viktor Mihajlovski , Robin Murphy , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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 Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, Feb 20, 2020 at 05:06:06PM +0100, Halil Pasic wrote: > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 867c7ebd3f10..fafc8f924955 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -243,6 +243,9 @@ static bool vring_use_dma_api(struct virtio_device *vdev) > if (!virtio_has_iommu_quirk(vdev)) > return true; > > + if (force_dma_unencrypted(&vdev->dev)) > + return true; Hell no. This is a detail of the platform DMA direct implementation. Drivers have no business looking at this flag, and virtio finally needs to be fixed to use the DMA API properly for everything but legacy devices. No amount of desparate hacks is going to fix that fundamental problem, and I'm starting to get really sick and tired of all the crap patches published in this area. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu