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 61189C54EAA for ; Fri, 27 Jan 2023 10:04:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233250AbjA0KEk (ORCPT ); Fri, 27 Jan 2023 05:04:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231743AbjA0KEi (ORCPT ); Fri, 27 Jan 2023 05:04:38 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F921DBD3 for ; Fri, 27 Jan 2023 02:04:10 -0800 (PST) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4P3Cng37j8z67PwL; Fri, 27 Jan 2023 18:03:19 +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 15.1.2375.34; Fri, 27 Jan 2023 10:04:07 +0000 Date: Fri, 27 Jan 2023 10:04:06 +0000 From: Jonathan Cameron To: Dan Williams CC: , Alison Schofield , Vishal Verma , "Ira Weiny" , Subject: Re: [PATCH] cxl/pci: Set the device timestamp Message-ID: <20230127100406.00006c65@Huawei.com> In-Reply-To: <63d2e0f67eee9_ea222294b6@dwillia2-xfh.jf.intel.com.notmuch> References: <20230126180458.5145-1-Jonathan.Cameron@huawei.com> <63d2e0f67eee9_ea222294b6@dwillia2-xfh.jf.intel.com.notmuch> 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 Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org On Thu, 26 Jan 2023 12:22:14 -0800 Dan Williams wrote: > Jonathan Cameron wrote: > > CXL r3.0 section 8.2.9.4.2 "Set Timestamp" recommends that the host sets > > the timestamp after every Conventional or CXL Reset to ensure accurate > > timestamps. This should include on initial boot up. The time base that > > is being set is used by a device for the poison list overflow timestamp > > and all event timestamps. Note that the command is optional and if > > not supported and the device cannot return accurate timestamps it will > > fill the fields in with an appropriate marker (see the specification > > description of each timestamp). > > > > Signed-off-by: Jonathan Cameron > > > > --- > > > > Open question: Should we only do this if Linux has control of the > > error handling? In theory it should be safe anyway given the > > specification is clear that the timestamp base should always be the > > same - so subject to small errors we shouldn't cause any firmware first > > handling to get confused. > > > > drivers/cxl/core/mbox.c | 25 +++++++++++++++++++++++++ > > drivers/cxl/cxlmem.h | 7 +++++++ > > drivers/cxl/pci.c | 5 +++++ > > include/uapi/linux/cxl_mem.h | 1 + > > 4 files changed, 38 insertions(+) > > > > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > > index b03fba212799..a7317bb142ed 100644 > > --- a/drivers/cxl/core/mbox.c > > +++ b/drivers/cxl/core/mbox.c > > @@ -65,6 +65,7 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = { > > CXL_CMD(GET_SCAN_MEDIA_CAPS, 0x10, 0x4, 0), > > CXL_CMD(SCAN_MEDIA, 0x11, 0, 0), > > CXL_CMD(GET_SCAN_MEDIA, 0, CXL_VARIABLE_PAYLOAD, 0), > > + CXL_CMD(SET_TIMESTAMP, 8, 0, 0), > > Is there a use case for userspace to need to send its own view > of 'timestamp' to the device? I think it's ok if this only a > kernel-internal thing. Fair enough. Easier to add the interface later if we need to than to rip it out. > > > }; > > > > /* > > @@ -93,6 +94,7 @@ static u16 cxl_disabled_raw_commands[] = { > > CXL_MBOX_OP_SET_SHUTDOWN_STATE, > > CXL_MBOX_OP_SCAN_MEDIA, > > CXL_MBOX_OP_GET_SCAN_MEDIA, > > + CXL_MBOX_OP_SET_TIMESTAMP, > > The criteria I have in mind for commands that should be added to this > list are things that need to have a kernel control point (like long > running background commands), or commands with data integrity > implications that only the kernel can reasonably manage (like shutdown > state). While it is odd for userspace to send its own timestamps via > debug kernel builds that enable raw commands, the side effects of > allowing this seem benign. Makes sense I'll drop it from this list. > > > }; > > > > /* > > @@ -857,6 +859,29 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds) > > } > > EXPORT_SYMBOL_NS_GPL(cxl_mem_create_range_info, CXL); > > > > +int cxl_set_timestamp(struct cxl_dev_state *cxlds, u64 ts) > > +{ > > + struct cxl_mbox_cmd mbox_cmd; > > + struct cxl_mbox_set_timestamp_in pi; > > + > > + /* > > + * Command is optional and functionality should not be affected if > > + * the command is not available. > > + */ > > + if (!test_bit(CXL_MEM_COMMAND_ID_SET_TIMESTAMP, cxlds->enabled_cmds)) > > + return 0; > > + > > + pi.timestamp = ts; > > cpu_to_le64()? Good point. Thanks, Jonathan