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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 41729C433E0 for ; Tue, 16 Feb 2021 15:50:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0A3E64D9E for ; Tue, 16 Feb 2021 15:50:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230303AbhBPPuu (ORCPT ); Tue, 16 Feb 2021 10:50:50 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2573 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229764AbhBPPur (ORCPT ); Tue, 16 Feb 2021 10:50:47 -0500 Received: from fraeml744-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Dg4xW0tBwz67pRK; Tue, 16 Feb 2021 23:43:11 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml744-chm.china.huawei.com (10.206.15.225) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 16 Feb 2021 16:50:05 +0100 Received: from localhost (10.47.75.223) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 16 Feb 2021 15:50:03 +0000 Date: Tue, 16 Feb 2021 15:48:57 +0000 From: Jonathan Cameron To: Ben Widawsky CC: , , , , , Bjorn Helgaas , "Chris Browy" , Christoph Hellwig , "Dan Williams" , David Hildenbrand , David Rientjes , Ira Weiny , "Jon Masters" , Rafael Wysocki , Randy Dunlap , Vishal Verma , "John Groves (jgroves)" , "Kelley, Sean V" Subject: Re: [PATCH v4 9/9] cxl/mem: Add payload dumping for debug Message-ID: <20210216154857.0000261d@Huawei.com> In-Reply-To: <20210216014538.268106-10-ben.widawsky@intel.com> References: <20210216014538.268106-1-ben.widawsky@intel.com> <20210216014538.268106-10-ben.widawsky@intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.75.223] X-ClientProxiedBy: lhreml717-chm.china.huawei.com (10.201.108.68) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 15 Feb 2021 17:45:38 -0800 Ben Widawsky wrote: > It's often useful in debug scenarios to see what the hardware has dumped > out. As it stands today, any device error will result in the payload not > being copied out, so there is no way to triage commands which weren't > expected to fail (and sometimes the payload may have that information). > > The functionality is protected by normal kernel security mechanisms as > well as a CONFIG option in the CXL driver. > > This was extracted from the original version of the CXL enabling patch > series. > > Signed-off-by: Ben Widawsky My gut feeling here is use a tracepoint rather than spamming the kernel log. Alternatively just don't bother merging this patch - it's on the list now anyway so trivial for anyone doing such debug to pick it up. Jonathan > --- > drivers/cxl/Kconfig | 13 +++++++++++++ > drivers/cxl/mem.c | 8 ++++++++ > 2 files changed, 21 insertions(+) > > diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig > index 97dc4d751651..3eec9276e586 100644 > --- a/drivers/cxl/Kconfig > +++ b/drivers/cxl/Kconfig > @@ -50,4 +50,17 @@ config CXL_MEM_RAW_COMMANDS > potential impact to memory currently in use by the kernel. > > If developing CXL hardware or the driver say Y, otherwise say N. > + > +config CXL_MEM_INSECURE_DEBUG > + bool "CXL.mem debugging" > + depends on CXL_MEM > + help > + Enable debug of all CXL command payloads. > + > + Some CXL devices and controllers support encryption and other > + security features. The payloads for the commands that enable > + those features may contain sensitive clear-text security > + material. Disable debug of those command payloads by default. > + If you are a kernel developer actively working on CXL > + security enabling say Y, otherwise say N. > endif > diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c > index dc608bb20a31..237b956f0be0 100644 > --- a/drivers/cxl/mem.c > +++ b/drivers/cxl/mem.c > @@ -342,6 +342,14 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm, > > /* #5 */ > rc = cxl_mem_wait_for_doorbell(cxlm); > + > + if (!cxl_is_security_command(mbox_cmd->opcode) || > + IS_ENABLED(CONFIG_CXL_MEM_INSECURE_DEBUG)) { > + print_hex_dump_debug("Payload ", DUMP_PREFIX_OFFSET, 16, 1, > + mbox_cmd->payload_in, mbox_cmd->size_in, > + true); > + } > + > if (rc == -ETIMEDOUT) { > cxl_mem_mbox_timeout(cxlm, mbox_cmd); > return rc;