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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_GIT 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 BC70BC43387 for ; Thu, 10 Jan 2019 13:44:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 961C82173B for ; Thu, 10 Jan 2019 13:44:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729048AbfAJNoo (ORCPT ); Thu, 10 Jan 2019 08:44:44 -0500 Received: from 8bytes.org ([81.169.241.247]:56476 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729047AbfAJNoh (ORCPT ); Thu, 10 Jan 2019 08:44:37 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 55FC0329; Thu, 10 Jan 2019 14:44:35 +0100 (CET) From: Joerg Roedel To: "Michael S . Tsirkin" , Jason Wang , 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, Joerg Roedel Subject: [PATCH 0/3] Fix virtio-blk issue with SWIOTLB Date: Thu, 10 Jan 2019 14:44:30 +0100 Message-Id: <20190110134433.15672-1-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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. 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(-) -- 2.17.1