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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 A4DD7C43387 for ; Mon, 14 Jan 2019 12:41:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77E8C20659 for ; Mon, 14 Jan 2019 12:41:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726467AbfANMlv (ORCPT ); Mon, 14 Jan 2019 07:41:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38624 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726449AbfANMlv (ORCPT ); Mon, 14 Jan 2019 07:41:51 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 349F5811DA; Mon, 14 Jan 2019 12:41:51 +0000 (UTC) Received: from [10.72.12.169] (ovpn-12-169.pek2.redhat.com [10.72.12.169]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9C41719C7C; Mon, 14 Jan 2019 12:41:40 +0000 (UTC) Subject: Re: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB To: Christoph Hellwig Cc: Joerg Roedel , "Michael S . Tsirkin" , Konrad Rzeszutek Wilk , Jens Axboe , virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jfehlig@suse.com, jon.grimm@amd.com, brijesh.singh@amd.com References: <20190110134433.15672-1-joro@8bytes.org> <5ae1341e-62ec-0478-552b-259eabf9fb17@redhat.com> <20190111091502.GC5825@8bytes.org> <38bcbd46-674c-348a-cbd6-66bd431e986a@redhat.com> <20190114095002.GA29874@lst.de> From: Jason Wang Message-ID: Date: Mon, 14 Jan 2019 20:41:37 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190114095002.GA29874@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 14 Jan 2019 12:41:51 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2019/1/14 下午5:50, Christoph Hellwig wrote: > On Mon, Jan 14, 2019 at 05:41:56PM +0800, Jason Wang wrote: >> On 2019/1/11 下午5:15, Joerg Roedel wrote: >>> On Fri, Jan 11, 2019 at 11:29:31AM +0800, Jason Wang wrote: >>>> Just wonder if my understanding is correct IOMMU_PLATFORM must be set for >>>> all virtio devices under AMD-SEV guests? >>> Yes, that is correct. Emulated DMA can only happen on the SWIOTLB >>> aperture, because that memory is not encrypted. The guest bounces the >>> data then to its encrypted memory. >>> >>> Regards, >>> >>> Joerg >> >> Thanks, have you tested vhost-net in this case. I suspect it may not work > Which brings me back to my pet pevee that we need to take actions > that virtio uses the proper dma mapping API by default with quirks > for legacy cases. The magic bypass it uses is just causing problems > over problems. Yes, I fully agree with you. This is probably an exact example of such problem. Thanks