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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 89A54C352A1 for ; Wed, 7 Dec 2022 17:49:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p2yXw-0001eS-SK; Wed, 07 Dec 2022 12:49:28 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p2yXu-0001eH-3e for qemu-devel@nongnu.org; Wed, 07 Dec 2022 12:49:26 -0500 Received: from mail-oa1-x31.google.com ([2001:4860:4864:20::31]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1p2yXq-0003Sc-L6 for qemu-devel@nongnu.org; Wed, 07 Dec 2022 12:49:25 -0500 Received: by mail-oa1-x31.google.com with SMTP id 586e51a60fabf-1433ef3b61fso22122814fac.10 for ; Wed, 07 Dec 2022 09:49:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=42ZUzXP0Q+K0r/qguonfBFATcxW0cNiAlCL9i/Wscvg=; b=mt+aoz2oR3QALOYfdYhaVdQLdrTonIVQiXJpD1iOUgtnl19WrEtejHpU7EHoat/XRA C4EfzuD4GJjdCYx3NPPSvkfTuBC/hULjRuU/q//xkZFW0V/o3yKGVV7wvwOD2MCk+yfy Bl1VbNVlfrEzcxCbsvBWsrvEopATN13PnJOJlyboOAH+T3yRi1hMbxpeMPx93lflJKr2 b1N2ptAe7tZ6rj8x/fpnIis7/A5Br4bR/xoKYZUMy07p/QWKERrVKJHkeDFIh6mUqj2i xDx0N8y0ljeHHuealqJrkXj7Pr5lAFRTvXa9uznutxTwAxYJErbBJxC5SwoP0r3IGJdI Fadw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=42ZUzXP0Q+K0r/qguonfBFATcxW0cNiAlCL9i/Wscvg=; b=RAuzYRuqOH0TRrCW/QOiVLJzJQLM7HOxzQS4Ge0aVHKW0BucaMZyXXvsEd1DQGVqFv OXmZ8Jcay7fJt8Mla7sOXBmIi/qX79MS185NovgOTbpcrupKCRlrkI4x1rYGtrxgBcJ+ 5uqNIq1Gk0rYdj4J0h6wjn2ydZOIJSqM685KufjhDjNC+fQKwCmGNWLcgLEoLTTBSg2n 7tUESx/a/KNqOiwm3Iu/2o7FWVf6LqI6JD+hbRRvKS46Dlg1IttjqHW22lsliONPaMia iVsELipbvQ3fuz3XDHZYvcg2LZqxnKLeJ3QOBpDX0Fn8rwjahMK12IqF/Q4mFaN0VAxG NGUA== X-Gm-Message-State: ANoB5pm8AdJMiZLeU7nhPEZAnnafuwMfmJyZXqmP1zrc46ZpVLM79piL Gqwnsidp4V9bDi5VurqZWDE= X-Google-Smtp-Source: AA0mqf5DlUdQO9qWCt/weAQRD6fa3eC4pONyakT2gRF8g1DF+1Thwh2SWeVUNLzIF2yx8qQYkc9DOg== X-Received: by 2002:a05:6870:f816:b0:144:687:9ac0 with SMTP id fr22-20020a056870f81600b0014406879ac0mr18726757oab.277.1670435360380; Wed, 07 Dec 2022 09:49:20 -0800 (PST) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id t27-20020a056870f21b00b001435fe636f2sm12409252oao.53.2022.12.07.09.49.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Dec 2022 09:49:19 -0800 (PST) Date: Wed, 7 Dec 2022 09:49:18 -0800 From: Guenter Roeck To: Jinhao Fan Cc: qemu-devel@nongnu.org, its@irrelevant.dk, kbusch@kernel.org Subject: Re: [PATCH v3 1/2] hw/nvme: Implement shadow doorbell buffer support Message-ID: <20221207174918.GA1151796@roeck-us.net> References: <20220616123408.3306055-1-fanjinhao21s@ict.ac.cn> <20220616123408.3306055-2-fanjinhao21s@ict.ac.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616123408.3306055-2-fanjinhao21s@ict.ac.cn> Received-SPF: pass client-ip=2001:4860:4864:20::31; envelope-from=groeck7@gmail.com; helo=mail-oa1-x31.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FORGED_FROMDOMAIN=0.21, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi, On Thu, Jun 16, 2022 at 08:34:07PM +0800, Jinhao Fan wrote: > Implement Doorbel Buffer Config command (Section 5.7 in NVMe Spec 1.3) > and Shadow Doorbel buffer & EventIdx buffer handling logic (Section 7.13 > in NVMe Spec 1.3). For queues created before the Doorbell Buffer Config > command, the nvme_dbbuf_config function tries to associate each existing > SQ and CQ with its Shadow Doorbel buffer and EventIdx buffer address. > Queues created after the Doorbell Buffer Config command will have the > doorbell buffers associated with them when they are initialized. > > In nvme_process_sq and nvme_post_cqe, proactively check for Shadow > Doorbell buffer changes instead of wait for doorbell register changes. > This reduces the number of MMIOs. > > In nvme_process_db(), update the shadow doorbell buffer value with > the doorbell register value if it is the admin queue. This is a hack > since hosts like Linux NVMe driver and SPDK do not use shadow > doorbell buffer for the admin queue. Copying the doorbell register > value to the shadow doorbell buffer allows us to support these hosts > as well as spec-compliant hosts that use shadow doorbell buffer for > the admin queue. > > Signed-off-by: Jinhao Fan I noticed that I can no longer boot Linux kernels from nvme on riscv64 systems. The problem is seen with qemu v7.1 and qemu v7.2-rc4. The log shows: [ 35.904128] nvme nvme0: I/O 642 (I/O Cmd) QID 1 timeout, aborting [ 35.905000] EXT4-fs (nvme0n1): mounting ext2 file system using the ext4 subsystem [ 66.623863] nvme nvme0: I/O 643 (I/O Cmd) QID 1 timeout, aborting [ 97.343989] nvme nvme0: Abort status: 0x0 [ 97.344355] nvme nvme0: Abort status: 0x0 [ 97.344647] nvme nvme0: I/O 7 QID 0 timeout, reset controller [ 97.350568] nvme nvme0: I/O 644 (I/O Cmd) QID 1 timeout, aborting This is with the mainline Linux kernel (v6.1-rc8). Bisect points to this patch. Reverting this patch and a number of associated patches (to fix conflicts) fixes the problem. 06143d8771 Revert "hw/nvme: Implement shadow doorbell buffer support" acb4443e3a Revert "hw/nvme: Use ioeventfd to handle doorbell updates" d5fd309feb Revert "hw/nvme: do not enable ioeventfd by default" 1ca1e6c47c Revert "hw/nvme: unregister the event notifier handler on the main loop" 2d26abd51e Revert "hw/nvme: skip queue processing if notifier is cleared" 99d411b5a5 Revert "hw/nvme: reenable cqe batching" 2293d3ca6c Revert "hw/nvme: Add trace events for shadow doorbell buffer" Qemu command line: qemu-system-riscv64 -M virt -m 512M \ -kernel arch/riscv/boot/Image -snapshot \ -device nvme,serial=foo,drive=d0 \ -drive file=rootfs.ext2,if=none,format=raw,id=d0 \ -bios default \ -append "root=/dev/nvme0n1 console=ttyS0,115200 earlycon=uart8250,mmio,0x10000000,115200" \ -nographic -monitor none Guenter