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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 D0E87C433E0 for ; Tue, 22 Dec 2020 13:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E71E229C5 for ; Tue, 22 Dec 2020 13:25:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726942AbgLVNZI (ORCPT ); Tue, 22 Dec 2020 08:25:08 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:53012 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726557AbgLVNZH (ORCPT ); Tue, 22 Dec 2020 08:25:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608643420; 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=9kISqIU8vAjOFBkpQnPPm5JuJX1GeR511WeyawMtRTI=; b=ZR3lyUAI8p0tQ0z6GNPIUGxN7CUG2H+C/WiukInnPb/NMhPcSirs8JJjKPnBQlzJDMxC7c RL6Bf7m5d/vLwFvoj6l+ACCQfSgntZuAr1y7OcyKq+3GO5dCSUCq8lLHcuQ1rsXounLKyj wqTnIBRxplMPt9+WXTROH4BGeb9RQGM= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-376-xjQ0nruUPci9z9Let6Vj_A-1; Tue, 22 Dec 2020 08:23:39 -0500 X-MC-Unique: xjQ0nruUPci9z9Let6Vj_A-1 Received: by mail-wm1-f72.google.com with SMTP id s130so1728511wme.0 for ; Tue, 22 Dec 2020 05:23:39 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=9kISqIU8vAjOFBkpQnPPm5JuJX1GeR511WeyawMtRTI=; b=KrPIOTIGucBLmK3bx9bLZZmAbSJvCNi8JTJqkluPwt7fwXgHFZnMoPEHRvV/dfuNK/ P8MizDsdQYwvnfBix/vvgmR+EFCviXpuBEGexY3CWrr1+uvMsq5y/gE5+GV9mQKd1Jj3 RdJ5qjwKEyBSd2Wad8BAL8CVpsC937zUgL9/mk8IzWqxWEy4+yr04pse+UJfdJi6QXc7 lhbaWtENlEoDFO7/rVATO2jCyuSY7fdj6nfym4vjYu/LcGRfByRi94nfEmZdOYPUDxu6 Bvnm4i/jfLNZXo5BCKR8iLdJvpq5jldg6GO9ERPosuMSUfZNhXA4+W5FykGpHOX/aE2Z XXrA== X-Gm-Message-State: AOAM533PMgglP7pOYtDmkPsVIhlu3KB4k84Bc8SXNRI+72/tc2etnhFw LnLaAobvbv+DQUHsiGkH7tQOu6JXk0HZUqGubmbFomj1oWBS3+bjsCqpePkcvYthCnLHB3ybAqQ 0ob9v5ljoUD79O6iBLVPLK+BS X-Received: by 2002:a05:600c:25c2:: with SMTP id 2mr22499138wml.170.1608643417882; Tue, 22 Dec 2020 05:23:37 -0800 (PST) X-Google-Smtp-Source: ABdhPJz9rysDLcWTp8Jau0zRAN0UDLnMWHjrfFFfXPkheRBJUpzOIBynVFrzYgP/JEQ2TVAAHWtjJw== X-Received: by 2002:a05:600c:25c2:: with SMTP id 2mr22499103wml.170.1608643417665; Tue, 22 Dec 2020 05:23:37 -0800 (PST) Received: from steredhat (host-79-34-249-199.business.telecomitalia.it. [79.34.249.199]) by smtp.gmail.com with ESMTPSA id j59sm32452847wrj.13.2020.12.22.05.23.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Dec 2020 05:23:37 -0800 (PST) Date: Tue, 22 Dec 2020 14:23:34 +0100 From: Stefano Garzarella To: Jason Wang Cc: virtualization@lists.linux-foundation.org, Stefan Hajnoczi , Laurent Vivier , linux-kernel@vger.kernel.org, Eli Cohen , "Michael S. Tsirkin" , Max Gurtovoy Subject: Re: [PATCH RFC 00/12] vdpa: generalize vdpa simulator and add block device Message-ID: <20201222132334.v34qfcjyhta6noen@steredhat> References: <20201113134712.69744-1-sgarzare@redhat.com> <93f207c0-61e6-3696-f218-e7d7ea9a7c93@redhat.com> <20201218113816.zcyeyqipux4ao4cp@steredhat> <7dd3ed02-36c3-fcfd-0a1d-9c31af6f473e@redhat.com> <20201221111423.sestfroiw2dgpluc@steredhat> <856d53c2-82e2-e408-76e6-24c92010f973@redhat.com> <20201222105733.4f6oou7lshi35qvc@steredhat> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 22, 2020 at 08:29:20PM +0800, Jason Wang wrote: > >On 2020/12/22 下午6:57, Stefano Garzarella wrote: >>On Tue, Dec 22, 2020 at 10:44:48AM +0800, Jason Wang wrote: >>> >>>On 2020/12/21 下午7:14, Stefano Garzarella wrote: >>>>On Mon, Dec 21, 2020 at 11:16:54AM +0800, Jason Wang wrote: >>>>> >>>>>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. >>>> >>>>Okay, so since we are using for simplicity an identical mapping, >>>>we are assigning the same dma_addr to multiple pages. >>> >>> >>>I think I get you now. That's the root cause for the failure. >> >>Yes, sorry, I didn't explain well previously. >> >>> >>>Then I think we need an simple iova allocator for vdpa simulator, >>>and it might be useful for VDUSE as well. >> >>Okay, I'll work on it. >>If you have an example to follow or some pointers, they are welcome :-) > > >Kernel had implemented one in iova.c but I'm not sure we need the >complexity like that. Or we can just use rbtree or idr to implement a >simpler one. Yeah, I found it and I started to integrate it in the simulator. Also if it appears complicated, it seams to me that it should be simple to integrate. I'll give it a try, and if it is too complicate, I'll switch to a simple rbtree. Thanks, Stefano