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 8DD59C61DA4 for ; Fri, 24 Feb 2023 12:03:51 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pVWmr-0005Ka-J8; Fri, 24 Feb 2023 07:02:54 -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 1pVWmW-0005HD-2r for qemu-devel@nongnu.org; Fri, 24 Feb 2023 07:02:42 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pVWmJ-0004dH-4I for qemu-devel@nongnu.org; Fri, 24 Feb 2023 07:02:28 -0500 Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4PNSzz42pWz6J7Ys; Fri, 24 Feb 2023 19:57:03 +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 15.1.2507.17; Fri, 24 Feb 2023 12:01:52 +0000 Date: Fri, 24 Feb 2023 12:01:51 +0000 To: Fan Ni CC: Gregory Price , Jonathan Cameron via , Michael Tsirkin , Ben Widawsky , "linux-cxl@vger.kernel.org" , "linuxarm@huawei.com" , Ira Weiny , Gregory Price , Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= , Mike Maslenkin Subject: Re: [PATCH 2/2] hw/cxl: Multi-Region CXL Type-3 Devices (Volatile and Persistent) Message-ID: <20230224120151.00007b79@Huawei.com> In-Reply-To: <20230224002940.GA1282789@bgt-140510-bm03> References: <20230131163847.23025-1-Jonathan.Cameron@huawei.com> <20230131163847.23025-3-Jonathan.Cameron@huawei.com> <20230217161617.000064d1@huawei.com> <20230220114646.000000ff@Huawei.com> <20230224002940.GA1282789@bgt-140510-bm03> 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="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml500002.china.huawei.com (7.191.160.78) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=185.176.79.56; envelope-from=jonathan.cameron@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-to: Jonathan Cameron From: Jonathan Cameron via Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, 24 Feb 2023 00:29:47 +0000 Fan Ni wrote: > On Mon, Feb 20, 2023 at 11:46:46AM +0000, Jonathan Cameron wrote: > > > On Fri, 17 Feb 2023 06:08:57 -0500 > > Gregory Price wrote: > > > > > On Fri, Feb 17, 2023 at 04:16:17PM +0000, Jonathan Cameron via wrote: > > > > On Tue, 31 Jan 2023 16:38:47 +0000 > > > > Jonathan Cameron via wrote: > > > > > > > > > From: Gregory Price > > > > > > > > > > This commit enables each CXL Type-3 device to contain one volatile > > > > > memory region and one persistent region. > > > > > > > > > > Two new properties have been added to cxl-type3 device initialization: > > > > > [volatile-memdev] and [persistent-memdev] > > > > > > > > > > The existing [memdev] property has been deprecated and will default the > > > > > memory region to a persistent memory region (although a user may assign > > > > > the region to a ram or file backed region). It cannot be used in > > > > > combination with the new [persistent-memdev] property. > > > > > > > > > > Partitioning volatile memory from persistent memory is not yet supported. > > > > > > > > > > Volatile memory is mapped at DPA(0x0), while Persistent memory is mapped > > > > > at DPA(vmem->size), per CXL Spec 8.2.9.8.2.0 - Get Partition Info. > > > > > > > > > > Signed-off-by: Gregory Price > > > > > Signed-off-by: Jonathan Cameron > > > > > > > > > Hi Gregory, > > > > > > > > I've added support for multiple HDM decoders and hence can now > > > > test both volatile and non volatile on same device. > > > > It very nearly all works. With one exception which is I couldn't > > > > poke the first byte of the non volatile region. > > > > > > > > I think we have an off by one in a single check. > > > > > > > > Interestingly it makes no difference when creating an FS on top > > > > (which was my standard test) so I only noticed when poking memory > > > > addresses directly to sanity check the HDM decoder setup. > > > > > > > > I'll roll a v2 if no one shouts out that I'm wrong. > > > > > > > > Note that adding multiple HDM decoders massively increases > > > > the number of test cases over what we had before to poke all the > > > > corners so I may well be missing stuff. Hopefully can send an RFC > > > > of that support out next week. > > > > > > > > Jonathan > > > > > > > > > > Very cool! Thanks for pushing this over the finishing line. > > > > > > All my testing so far has been really smooth since getting the TCG issue > > > worked out. > > > > > > > > -MemTxResult cxl_type3_read(PCIDevice *d, hwaddr host_addr, uint64_t *data, > > > > > - unsigned size, MemTxAttrs attrs) > > > [...] > > > > > + if (vmr) { > > > > > + if (*dpa_offset <= int128_get64(vmr->size)) { > > > > > > > > Off by one I think. < > > > > > > > > > > Yes that makes sense, should be <. Derp derp. > > > > > > Though I think this may alludes to more off-by-one issues? This says > > > > > > if (dpa_offset < vmr->size) > > > > > > but dpa_offset should be (hpa - memory_region_base), > > > > > > The HPA is used by memory access routing for the whole system to determine > > > what device it should access. > > > > > > If that corner case is being hit, doesn't it imply the higher level code > > > is also susceptible to this, and is routing accesses to the wrong device? > > > > I don't think so though I may be missing something. > > > > Say vmr->size = 8 > > > > hpa dpa_offset > > 0 0 > > 1 1 > > 2 2 > > 3 3 > > 4 4 > > 5 5 > > 6 6 > > 7 7 > > 8 0 > > > > etc > > If vmr->size=8, we should expect that at most 8 offsets (e.g., hpa [0,7]) will > access vmem and hpa=8 will access offset=0 at pmem, right? > If with hpa=8, dpa_offset round to 0, does it mean we never get a > dpa_offset larger than 7? If so, when pmem will be accessed? Ah. I didn't mention that when HPA == 8 in this example the dpa_offset is now used to access pmem until we reach vmr->size + persistent_mr->size at which point it is off the end and it's routed no where at all. Table is too simplisitic! > > > > > Also the writes are turning up where I expect them to. > > > > Also just noticed that the code is setting Memory_base in the CXL dvsec. > > Given we are emulating a device as if it has been freshly powered up > > those should not be set - it's the OS or firmware's job to set them up. > > Harmless though, so can be a cleanup to follow the main series. > > > > We don't currently handle dvsec range based routing anyway and > > I'm not sure we ever will as it is a pain to test without some firmware > > or OS code to program them for us. > > > > Note that if you update your kernel to cxl/next it will currently fail > > as the Range register emulation is (I think) rather over enthusiastic > > and currently decides to emulate the HDM decoders for the QEMU emulated > > type 3 devices. > > > > https://lore.kernel.org/linux-cxl/167640366272.935665.1056268838301725481.stgit@dwillia2-xfh.jf.intel.com/T/#m6c025d5c9b27d8360a64079593f6c5adaa408772 > > > > Jonathan > > > > > > > > > > ~Gregory > > > >