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=-10.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,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 B2F96C433E0 for ; Mon, 21 Dec 2020 03:18:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81A1822D02 for ; Mon, 21 Dec 2020 03:18:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727457AbgLUDSg (ORCPT ); Sun, 20 Dec 2020 22:18:36 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:41048 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725927AbgLUDSg (ORCPT ); Sun, 20 Dec 2020 22:18:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608520629; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CsblJmOtG9tZ7kKpi056Ey60jmaFEOA9x9uDqAciUmU=; b=U26u+H8z2jE57EbssurlHbbfc26HjDg531dFJNm4Nyn+N+Go715E+NpRB7baGGurw/DrO8 GtV2Ik28y3rLqeCImEvzIVVY1y+keQ0Uauzqgi8/tUlDIF3L7MolSd9PHTQxZquoVCdzlb vAPYu7wi4TOrEGn9KzCroCOvAI5gnlA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-564-Sm0RUi0JMFO9BXgQjLPUpA-1; Sun, 20 Dec 2020 22:17:07 -0500 X-MC-Unique: Sm0RUi0JMFO9BXgQjLPUpA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 56008800D55; Mon, 21 Dec 2020 03:17:06 +0000 (UTC) Received: from [10.72.12.173] (ovpn-12-173.pek2.redhat.com [10.72.12.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id E75575D9CA; Mon, 21 Dec 2020 03:16:55 +0000 (UTC) Subject: Re: [PATCH RFC 00/12] vdpa: generalize vdpa simulator and add block device To: Stefano Garzarella Cc: virtualization@lists.linux-foundation.org, Stefan Hajnoczi , Laurent Vivier , linux-kernel@vger.kernel.org, Eli Cohen , "Michael S. Tsirkin" , Max Gurtovoy References: <20201113134712.69744-1-sgarzare@redhat.com> <93f207c0-61e6-3696-f218-e7d7ea9a7c93@redhat.com> <20201218113816.zcyeyqipux4ao4cp@steredhat> From: Jason Wang Message-ID: <7dd3ed02-36c3-fcfd-0a1d-9c31af6f473e@redhat.com> Date: Mon, 21 Dec 2020 11:16:54 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201218113816.zcyeyqipux4ao4cp@steredhat> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/12/18 下午7:38, Stefano Garzarella wrote: > On Mon, Nov 16, 2020 at 11:37:48AM +0800, Jason Wang wrote: >> >> On 2020/11/13 下午9:47, Stefano Garzarella wrote: >>> Thanks to Max that started this work! >>> I took his patches, and extended the block simulator a bit. >>> >>> This series moves the network device simulator in a new module >>> (vdpa_sim_net) and leaves the generic functions in the vdpa_sim core >>> module, allowing the possibility to add new vDPA device simulators. >>> Then we added a new vdpa_sim_blk module to simulate a block device. >>> >>> I'm not sure about patch 11 ("vringh: allow vringh_iov_xfer() to skip >>> bytes when ptr is NULL"), maybe we can add a new functions instead of >>> modify vringh_iov_xfer(). >>> >>> As Max reported, I'm also seeing errors with vdpa_sim_blk related to >>> iotlb and vringh when there is high load, these are some of the error >>> messages I can see randomly: >>> >>>   vringh: Failed to access avail idx at 00000000e8deb2cc >>>   vringh: Failed to read head: idx 6289 address 00000000e1ad1d50 >>>   vringh: Failed to get flags at 000000006635d7a3 >>> >>>   virtio_vdpa vdpa0: vringh_iov_push_iotlb() error: -14 offset:   >>> 0x2840000 len: 0x20000 >>>   virtio_vdpa vdpa0: vringh_iov_pull_iotlb() error: -14 offset:   >>> 0x58ee000 len: 0x3000 >>> >>> These errors should all be related to the fact that iotlb_translate() >>> fails with -EINVAL, so it seems that we miss some mapping. >> >> >> Is this only reproducible when there's multiple co-current accessing >> of IOTLB? If yes, it's probably a hint that some kind of >> synchronization is still missed somewhere. >> >> It might be useful to log the dma_map/unmp in both virtio_ring and >> vringh to see who is missing the map. >> > > Just an update about these issues with vdpa-sim-blk. > I've been focusing a little bit on these failures over the last few > days and have found two issues related to the IOTLB/IOMMU: > > 1. Some requests coming from the block layer fills the SG list with > multiple buffers that had the same physical address. This happens for > example while using 'mkfs', at some points multiple sectors are zeroed > so multiple SG elements point to the same physical page that is zeroed. > Since we are using vhost_iotlb_del_range() in the > vdpasim_unmap_page(), this removes all the overlapped ranges. I fixed > removing a single map in vdpasim_unmap_page(), but has an alternative > we can implement some kind of reference counts. I think we need to do what hardware do. So using refcount is probably not a good ida. > > 2. There was a race between dma_map/unmap and the worker thread, since > both are accessing the IOMMU. Taking the iommu_lock while using > vhost_iotlb_* API in the worker thread fixes the "vringh: Failed to *" > issues. > > Whit these issues fixed the vdpa-blk simulator seems to work well. > I'll send the patches next week or after the break. Good to know this. Thanks > > Thanks, > Stefano >