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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AF30C3DA6F for ; Wed, 23 Aug 2023 17:03:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232076AbjHWRDa convert rfc822-to-8bit (ORCPT ); Wed, 23 Aug 2023 13:03:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbjHWRD3 (ORCPT ); Wed, 23 Aug 2023 13:03:29 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0182E68 for ; Wed, 23 Aug 2023 10:03:26 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4RWCFY586hz67Q5S for ; Thu, 24 Aug 2023 01:02:41 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Wed, 23 Aug 2023 18:03:24 +0100 Date: Wed, 23 Aug 2023 18:03:23 +0100 From: Jonathan Cameron To: Ravi Kanth CC: , Sajjan Rao Subject: Re: Support for CXL v3.0 spec with QEMU Message-ID: <20230823180323.000052d5@Huawei.com> In-Reply-To: References: <20230810173322.0000543c@Huawei.com> <20230811145223.000040de@Huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On Wed, 16 Aug 2023 17:11:17 +0530 Ravi Kanth wrote: > Thanks, Jonathan. We were able to now see the CCI endpoint in the lspci output. > > However, we are not able to see the /dev/cxl/switch0 node. Should we > be loading the cxl driver with the changes suggested by you in the > link below? If yes, We are not able to download the source code as we > do not see the git repository for the same. Is this part of the > mainline? Not yet part of mainline so you will have to apply the patches and build a custom kernel. Jonathan > > https://lore.kernel.org/linux-cxl/20230804115414.14391-1-Jonathan.Cameron@huawei.com/T/#t > > Ravi > > On Fri, Aug 11, 2023 at 7:22 PM Jonathan Cameron > wrote: > > > > On Fri, 11 Aug 2023 17:34:33 +0530 > > Ravi Kanth wrote: > > > > > Hi Jonathan, > > > We build qemu with your repository code but we do not see any changes > > > in the output of lspci. Do we have any prerequisites / command > > > parameters w.r.t on how we boot the qemu for your changes to take > > > effect? Please let us know. > > > > As the switch cci is a separate PCI function it needs to be explicitly > > added. See the cover letter of kernel switch-cci RFC: > > > > https://lore.kernel.org/linux-cxl/20230804115414.14391-1-Jonathan.Cameron@huawei.com > > > > -device cxl-upstream,bus=cxl_rp_port0,id=us0,addr=0.0,multifunction=on, \ > > -device cxl-switch-mailbox-cci,bus=cxl_rp_port0,addr=0.1,target=us0 \ > > -device cxl-downstream,port=0,bus=us0,id=swport0,chassis=0,slot=4 \ > > -device cxl-downstream,port=1,bus=us0,id=swport1,chassis=0,slot=5 \ > > > > Is the switch part of it. > > > > We don't yet have the additions for MHDs though some discussion on how to > > do it has happened. Those will support some FMAPI command via tunnelling throuhg > > the main mailbox. > > > > I'm on vacation from tonight until the 22nd, so good luck. Feel free > > to post questions in meantime but my reply will take a while! > > > > Jonathan > > > > > > > > Thanks for your help. > > > > > > Thanks > > > Ravi > > > > > > On Thu, Aug 10, 2023 at 10:10 PM Ravi Kanth wrote: > > > > > > > > Thanks Jonathan for pointing this out. I will definitely take a look > > > > at this. Current support for the simulation of CCI mailbox is only via > > > > MCTP messages or even via CXL driver IOCTLs? > > > > > > > > Ravi > > > > > > > > On Thu, Aug 10, 2023 at 10:03 PM Jonathan Cameron > > > > wrote: > > > > > > > > > > On Thu, 10 Aug 2023 21:42:12 +0530 > > > > > Ravi Kanth wrote: > > > > > > > > > > > Hello, > > > > > > > > > > Hi Ravi, > > > > > > > > > > > > > > > > > I am writing this mail to know if the latest QEMU has support for CXL > > > > > > spec v3.0? I understand from the older tutorials that QEMU has support > > > > > > for CXL v2.0. Is there any update to QEMU to support the CXL v3.0? I > > > > > > would like to specifically test the CCI mailbox functionality which > > > > > > has been added to CXL v3.0 spec. > > > > > > > > > > The nature of the CXL specification and the QEMU support is that for > > > > > devices there isn't a clear divide between different generations of > > > > > the specification. By that I mean, that a device based on the CXL 2.0 > > > > > specification is compatible with the CXL 3.0 specification. As such, > > > > > the QEMU emulation has focused on features of interest - it is a far > > > > > from complete implementation of all the options in the CXL 2.0 > > > > > specification but conversely there are some parts of CXL 3.0 are supported. > > > > > > > > > > Note that the particular CCI functionality is not yet ready for CXL upstream, > > > > > but we do have some support in the staging tree I maintain. > > > > > > > > > > https://gitlab.com/jic23/qemu/-/commits/cxl-2023-08-07/ > > > > > specifically > > > > > https://gitlab.com/jic23/qemu/-/commit/2eb7e6402a45b359c304cea894a1d27625a4b80c > > > > > > > > > > Note at this stage we only support subset of commands. > > > > > Contributions of more support welcomed! > > > > > > > > > > Intent of the current support and related MCTP CCI access (over I2C) is > > > > > to enable ecosystem development, particularly of fabric managers. > > > > > For that a tiny subset of commands was sufficient to be sure the architecture > > > > > inside QEMU worked and that the proposed kernel code functions correctly. > > > > > > > > > > Jonathan > > > > > > > > > > > > > > > > > Thank you in advance for your assistance. > > > > > > > > > > > > Ravi > > > > > > > > > > > > > > > > > -- > > > > Regards > > > > M.V.R.Ravi Kanth > > > > > > > > > > > > >