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 2C571C43387 for ; Fri, 11 Jan 2019 03:29:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 037AC2146F for ; Fri, 11 Jan 2019 03:29:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728015AbfAKD3o (ORCPT ); Thu, 10 Jan 2019 22:29:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39818 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727957AbfAKD3o (ORCPT ); Thu, 10 Jan 2019 22:29:44 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 726E573A62; Fri, 11 Jan 2019 03:29:43 +0000 (UTC) Received: from [10.72.12.143] (ovpn-12-143.pek2.redhat.com [10.72.12.143]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 992D65C219; Fri, 11 Jan 2019 03:29:34 +0000 (UTC) Subject: Re: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB To: Joerg Roedel , "Michael S . Tsirkin" , Konrad Rzeszutek Wilk Cc: 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, hch@lst.de References: <20190110134433.15672-1-joro@8bytes.org> From: Jason Wang Message-ID: <5ae1341e-62ec-0478-552b-259eabf9fb17@redhat.com> Date: Fri, 11 Jan 2019 11:29:31 +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: <20190110134433.15672-1-joro@8bytes.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 11 Jan 2019 03:29:43 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2019/1/10 下午9:44, Joerg Roedel wrote: > Hi, > > there is a problem with virtio-blk driven devices when > virtio-ring uses SWIOTLB through the DMA-API. This happens > for example in AMD-SEV enabled guests, where the guest RAM > is mostly encrypted and all emulated DMA has to happen > to/from the SWIOTLB aperture. > > The problem is a limitation of the SWIOTLB implementation, > which does not support allocations larger than 256kb. When > the virtio-blk driver tries to read/write a block larger > than that, the allocation of the dma-handle fails and an IO > error is reported. > > This patch-set adds a check to the virtio-code whether it > might be using SWIOTLB bounce buffering and limits the > maximum segment size in the virtio-blk driver in this case, > so that it doesn't try to do larger reads/writes. Just wonder if my understanding is correct IOMMU_PLATFORM must be set for all virtio devices under AMD-SEV guests? Thanks > > Please review. > > Thanks, > > Joerg > > Joerg Roedel (3): > swiotlb: Export maximum allocation size > virtio: Introduce virtio_max_dma_size() > virtio-blk: Consider virtio_max_dma_size() for maximum segment size > > drivers/block/virtio_blk.c | 10 ++++++---- > drivers/virtio/virtio_ring.c | 11 +++++++++++ > include/linux/swiotlb.h | 12 ++++++++++++ > include/linux/virtio.h | 2 ++ > 4 files changed, 31 insertions(+), 4 deletions(-) >