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 72202C61DA4 for ; Thu, 2 Feb 2023 09:58:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229667AbjBBJ60 (ORCPT ); Thu, 2 Feb 2023 04:58:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229929AbjBBJ60 (ORCPT ); Thu, 2 Feb 2023 04:58:26 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDA20303C4 for ; Thu, 2 Feb 2023 01:58:24 -0800 (PST) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4P6vJv1ZlYz6J67l; Thu, 2 Feb 2023 17:54:39 +0800 (CST) Received: from localhost (10.81.211.68) 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; Thu, 2 Feb 2023 09:58:22 +0000 Date: Thu, 2 Feb 2023 09:58:21 +0000 From: Jonathan Cameron To: Ira Weiny CC: Dan Williams , "Jiang, Dave" , Alison Schofield , Vishal Verma , Ben Widawsky , Robert Richter , Subject: Re: [PATCH v3 3/4] cxl/uapi: Tag commands from cxl_query_cmd() Message-ID: <20230202095821.00001a98@Huawei.com> In-Reply-To: <20221222-cxl-misc-v3-3-60d4f35e4b39@intel.com> References: <20221222-cxl-misc-v3-0-60d4f35e4b39@intel.com> <20221222-cxl-misc-v3-3-60d4f35e4b39@intel.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="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.81.211.68] X-ClientProxiedBy: lhrpeml500001.china.huawei.com (7.191.163.213) 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, 01 Feb 2023 17:23:12 -0800 Ira Weiny wrote: > It was pointed out that commands not supported by the device or excluded > by the kernel were being returned in cxl_query_cmd().[1] > > While libcxl correctly handles failing commands, it is more efficient to > not issue an invalid command in the first place. This can't be done > without additional information being returned from cxl_query_cmd(). In > addition, information about the availability of commands can be useful > for debugging. > > Add flags to struct cxl_command_info which reflect if a command is > enabled and/or exclusive to the kernel. > > [1] https://lore.kernel.org/all/63b4ec4e37cc1_5178e2941d@dwillia2-xfh.jf.intel.com.notmuch/ > > Suggested-by: Dan Williams > Signed-off-by: Ira Weiny No mention of why we can use space in the existing defined flag mask? I couldn't find a reason why we couldn't previously but Dan's proposal was to reserve that first bit so I'm wondering on the reasoning one way or the other! Other than that detail, this looks like a good solution to me. Jonathan > > --- > Changes for v3: > Dan > Pass enabled/exclusive flags to user space rather than > masking those commands. > --- > drivers/cxl/core/mbox.c | 9 +++++++-- > include/uapi/linux/cxl_mem.h | 4 +++- > 2 files changed, 10 insertions(+), 3 deletions(-) > > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > index b03fba212799..6ab4613f3cf9 100644 > --- a/drivers/cxl/core/mbox.c > +++ b/drivers/cxl/core/mbox.c > @@ -445,9 +445,14 @@ int cxl_query_cmd(struct cxl_memdev *cxlmd, > * structures. > */ > cxl_for_each_cmd(cmd) { > - const struct cxl_command_info *info = &cmd->info; > + struct cxl_command_info info = cmd->info; > > - if (copy_to_user(&q->commands[j++], info, sizeof(*info))) > + if (test_bit(info.id, cxlmd->cxlds->enabled_cmds)) > + info.flags |= CXL_MEM_COMMAND_FLAG_ENABLED; > + if (test_bit(info.id, cxlmd->cxlds->exclusive_cmds)) > + info.flags |= CXL_MEM_COMMAND_FLAG_EXCLUSIVE; > + > + if (copy_to_user(&q->commands[j++], &info, sizeof(info))) > return -EFAULT; > > if (j == n_commands) > diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h > index 459a3f7f764b..4aee64b7cc1a 100644 > --- a/include/uapi/linux/cxl_mem.h > +++ b/include/uapi/linux/cxl_mem.h > @@ -91,7 +91,9 @@ struct cxl_command_info { > __u32 id; > > __u32 flags; > -#define CXL_MEM_COMMAND_FLAG_MASK GENMASK(0, 0) > +#define CXL_MEM_COMMAND_FLAG_MASK GENMASK(1, 0) > +#define CXL_MEM_COMMAND_FLAG_ENABLED BIT(0) > +#define CXL_MEM_COMMAND_FLAG_EXCLUSIVE BIT(1) > > __u32 size_in; > __u32 size_out; >