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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 95E94C7618B for ; Wed, 24 Jul 2019 12:53:25 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 6B976218B8 for ; Wed, 24 Jul 2019 12:53:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B976218B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51358 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqGlo-0002TS-LH for qemu-devel@archiver.kernel.org; Wed, 24 Jul 2019 08:53:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56641) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqGle-000250-Iu for qemu-devel@nongnu.org; Wed, 24 Jul 2019 08:53:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hqGlZ-00052X-Mh for qemu-devel@nongnu.org; Wed, 24 Jul 2019 08:53:10 -0400 Received: from mga03.intel.com ([134.134.136.65]:11067) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hqGlZ-0004rq-2u for qemu-devel@nongnu.org; Wed, 24 Jul 2019 08:53:09 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Jul 2019 05:53:00 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,302,1559545200"; d="scan'208";a="163836345" Received: from yangzhon-virtual.bj.intel.com (HELO localhost) ([10.238.145.78]) by orsmga008.jf.intel.com with ESMTP; 24 Jul 2019 05:52:58 -0700 Date: Wed, 24 Jul 2019 20:47:45 +0800 From: Yang Zhong To: Paolo Bonzini Message-ID: <20190724124745.GB3369@yangzhon-Virtual> References: <7A85DF989CAE8F42902CF7B31A7D94A1487D6D13@shsmsx102.ccr.corp.intel.com> <93e3762a-d906-6d6b-9a5f-7497af188f94@redhat.com> <20190724065513.GA3369@yangzhon-Virtual> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.65 Subject: Re: [Qemu-devel] The WCE issue in guest when i enable WCE in Qemu side. X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: yang.zhong@intel.com, "qemu-devel@nongnu.org" , Stefan Hajnoczi , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jul 24, 2019 at 10:57:30AM +0200, Paolo Bonzini wrote: > On 24/07/19 08:55, Yang Zhong wrote: > > > > The SPDK code i am using is latest version, So, i feel we should > > enable WCE feature in SPDK side by default. thanks for your help! > > Note that enabling the CONFIG_WCE feature has some consequences. > According to the spec: > > - if the VIRTIO_BLK_F_CONFIG_WCE feature was negotiated and the > writeback field in configuration space was 0 all the time between the > submission of the write and its completion, the device MUST ensure that > stable writes are committed to persistent storage before reporting > completion of the write. This means using FUA writes or something like that > > - the device MUST offset VIRTIO_BLK_F_FLUSH if they offer > VIRTIO_BLK_F_CONFIG_WCE > > - if VIRTIO_BLK_F_CONFIG_WCE is negotiated but VIRTIO_BLK_F_FLUSH is > not, the device MUST initialize writeback to 0 > Paolo, thanks for your reminder, these info are very helpful to me:), thanks, Yang. > Paolo