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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 23251C433ED for ; Mon, 3 May 2021 18:28:24 +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 AA3876112F for ; Mon, 3 May 2021 18:28:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA3876112F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42202 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lddIs-0002Ta-L0 for qemu-devel@archiver.kernel.org; Mon, 03 May 2021 14:28:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37584) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lddIE-0001qf-N6 for qemu-devel@nongnu.org; Mon, 03 May 2021 14:27:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:56469) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lddIB-0003U1-Sb for qemu-devel@nongnu.org; Mon, 03 May 2021 14:27:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620066459; 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=1E+BaIjDxhZl6GZ7y81/Hi7Q9ChK6qWJNShgYtoeN+8=; b=SOfMX+T/moEbEZLKGuJcqV5Yx6wlToQNqcChcxZJMzPUvSLKhVk0E+HRxitchvRfDaInTO lJl45ZYmcEvNENRZddzXXcIaIU4vahSLThuRoLNlu9wNtxga/k9c7yWRN78uMJbVFsRFQU cbde2Sd13XQ+G0FZ5gi0tA0EK03b9HY= 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-366-1VUIJ22kPluutAz6Czm1Rw-1; Mon, 03 May 2021 14:27:35 -0400 X-MC-Unique: 1VUIJ22kPluutAz6Czm1Rw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CA43318B9F41; Mon, 3 May 2021 18:27:32 +0000 (UTC) Received: from [10.3.114.144] (ovpn-114-144.phx2.redhat.com [10.3.114.144]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 608806061F; Mon, 3 May 2021 18:27:23 +0000 (UTC) Subject: Re: [PATCH v4 3/3] nvdimm: Enable sync-dax device property for nvdimm To: Shivaprasad G Bhat , david@gibson.dropbear.id.au, groug@kaod.org, qemu-ppc@nongnu.org, ehabkost@redhat.com, marcel.apfelbaum@gmail.com, mst@redhat.com, imammedo@redhat.com, xiaoguangrong.eric@gmail.com, peter.maydell@linaro.org, qemu-arm@nongnu.org, richard.henderson@linaro.org, pbonzini@redhat.com, stefanha@redhat.com, haozhong.zhang@intel.com, shameerali.kolothum.thodi@huawei.com, kwangwoo.lee@sk.com, armbru@redhat.com References: <161966810162.652.13723419108625443430.stgit@17be908f7c1c> <161966813983.652.5749368609701495826.stgit@17be908f7c1c> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Mon, 3 May 2021 13:27:22 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <161966813983.652.5749368609701495826.stgit@17be908f7c1c> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: linux-nvdimm@lists.01.org, aneesh.kumar@linux.ibm.com, qemu-devel@nongnu.org, kvm-ppc@vger.kernel.org, shivaprasadbhat@gmail.com, bharata@linux.vnet.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/28/21 10:49 PM, Shivaprasad G Bhat wrote: > The patch adds the 'sync-dax' property to the nvdimm device. > > When the sync-dax is 'direct' indicates the backend is synchronous DAX > capable and no explicit flush requests are required. When the mode is > set to 'writeback' it indicates the backend is not synhronous DAX synchronous > capable and explicit flushes to Hypervisor are required. > > On PPC where the flush requests from guest can be honoured by the qemu, s/the qemu/qemu/ > the 'writeback' mode is supported and set as the default. The device > tree property "hcall-flush-required" is added to the nvdimm node which > makes the guest to issue H_SCM_FLUSH hcalls to request for flushes s/to issue/issue/ s/request for/request/ > explicitly. This would be the default behaviour without sync-dax > property set for the nvdimm device. For old pSeries machine, the > default is 'unsafe'. > > For non-PPC platforms, the mode is set to 'unsafe' as the default. > > Signed-off-by: Shivaprasad G Bhat > --- > +++ b/qapi/common.json > @@ -197,3 +197,23 @@ > { 'enum': 'GrabToggleKeys', > 'data': [ 'ctrl-ctrl', 'alt-alt', 'shift-shift','meta-meta', 'scrolllock', > 'ctrl-scrolllock' ] } > + > +## > +# @NvdimmSyncModes: > +# > +# Indicates the mode of flush to be used to ensure persistence in case > +# of power failures. > +# > +# @unsafe: This is to indicate, the data on the backend device not be > +# consistent in power failure scenarios. s/This is to indicate, the/This indicates that/ s/device not/device might not/ > +# @direct: This is to indicate the backend device supports synchronous DAX > +# and no explicit flush requests from the guest is required. This indicates the backend device supports synchronous DAX, and no explicit flush requests from the guest are required. > +# @writeback: To be used when the backend device doesn't support synchronous > +# DAX. The hypervisor issues flushes to the disk when requested > +# by the guest. > +# Since: 6.0 6.1 > +# > +## > +{ 'enum': 'NvdimmSyncModes', > + 'data': [ 'unsafe', 'writeback', > + { 'name': 'direct', 'if': 'defined(CONFIG_LIBPMEM)' } ] } > > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org