Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 19 Feb 2021 20:03:57 -0500
From:   Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To:     Ben Widawsky <ben.widawsky@intel.com>
Cc:     linux-cxl@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org,
        linux-pci@vger.kernel.org, Bjorn Helgaas <helgaas@kernel.org>,
        Chris Browy <cbrowy@avery-design.com>,
        Christoph Hellwig <hch@infradead.org>,
        Dan Williams <dan.j.williams@intel.com>,
        David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Jon Masters <jcm@jonmasters.org>,
        Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
        Rafael Wysocki <rafael.j.wysocki@intel.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Vishal Verma <vishal.l.verma@intel.com>,
        "John Groves (jgroves)" <jgroves@micron.com>,
        "Kelley, Sean V" <sean.v.kelley@intel.com>,
        Ariel Sibley <Ariel.Sibley@microchip.com>
Subject: Re: [PATCH v5 5/9] cxl/mem: Add a "RAW" send command
Message-ID: <YDBf/QD8LMFi6JbH@Konrads-MacBook-Pro.local>
References: <20210217040958.1354670-1-ben.widawsky@intel.com>
 <20210217040958.1354670-6-ben.widawsky@intel.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210217040958.1354670-6-ben.widawsky@intel.com>
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from Konrads-MacBook-Pro.local (209.6.208.110) by SN4PR0201CA0061.namprd02.prod.outlook.com (2603:10b6:803:20::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3868.27 via Frontend Transport; Sat, 20 Feb 2021 01:04:00 +0000
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: 7c7aa21b-271e-4ef8-90b1-08d8d53b6a06
X-MS-TrafficTypeDiagnostic: BYAPR10MB2614:
X-Microsoft-Antispam-PRVS: <BYAPR10MB2614D12070AC530E789E85C989839@BYAPR10MB2614.namprd10.prod.outlook.com>
X-MS-Oob-TLC-OOBClassifiers: OLM:7691;
X-MS-Exchange-SenderADCheck: 1
X-Microsoft-Antispam: BCL:0;
X-Microsoft-Antispam-Message-Info: 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
X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR10MB2999.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(396003)(39860400002)(136003)(376002)(346002)(366004)(6666004)(8936002)(186003)(16526019)(6506007)(83380400001)(52116002)(7696005)(26005)(7416002)(8676002)(6916009)(54906003)(86362001)(66476007)(66946007)(316002)(4326008)(55016002)(9686003)(956004)(478600001)(2906002)(5660300002)(66556008);DIR:OUT;SFP:1101;
X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?zF8fLcBnSJWCnJTnGcMSbR3JxfRoEIfbfVY8AYCPnX7mCiVXK5NP1BnYK0Y3?=
 =?us-ascii?Q?YSD8L75koEwW8iPwO7Xqac58zXsx7M1eH/bOaHopCYxxx7wgO3qlp7g/g7yj?=
 =?us-ascii?Q?35Q01bYXhcHspzoeIBor7uBP7BZW5KAqTJwZLL8By+IS9zRKECDf2Vojix26?=
 =?us-ascii?Q?+IprJUCm30f1VbV7As5Uz8mhMgJxvX+s+SaAeSqGQ7scTCZwrERKLL8unQHW?=
 =?us-ascii?Q?ppFgdJ8gSdTzV6VT7NncpnhGH0nDvExfWIKGkMnH1r8Nz9pG79h1Hwbmdngy?=
 =?us-ascii?Q?ON9BmstowmN6tKt7C/WGuO8YjZIG30Z1MC1MExK1pZTvEFa6awZ8lj7SO3gp?=
 =?us-ascii?Q?nKbFWqwIlU90nKQQJrvrjb/AchHdsBuBNfprbFWvw68EcfFGqvcGah5720I+?=
 =?us-ascii?Q?pyErSmiRNXcwX1PK+mYVQbvguQVNOm4vASapCBJocHRlh3G4qNHTH1yfcXat?=
 =?us-ascii?Q?4aZK2pxhma9qTLw2SsR9pfJNnpZY1WUrW+XdFmYulDAmR/bZbwQGBCE4Mn8n?=
 =?us-ascii?Q?JlK29pcGzd3n1KO/wXwyDiZtwDKF8KcKb9lQq78UP3XgET/T+u3p8Nh/EW6i?=
 =?us-ascii?Q?12GOSE6tMfYZKhIvN0NzZGlA3m/b5t1z5m36XpiFNTfzJUr/6gVwZpHaZRSR?=
 =?us-ascii?Q?zqB9wtjsULaWkyl7AkaLXbkwe7gQtuch36/7E7vfP65w2O4g/vENQD9thgOl?=
 =?us-ascii?Q?9ahj5WEAr7tLIgt2XBHGTsKx5LM44/qj5r5ALiAIoICFRBag0TfQWmgVo0gh?=
 =?us-ascii?Q?0PmFARM5pZG9vMPcwRbYvaPXC2sWvvNKyZuiqWiC5WaHz1gq/6QqCOztUR2n?=
 =?us-ascii?Q?5rd9Oi9EDDM5VaBqli3rO4RG0k9YduX+6vO2A0MJCye4DkkIhAPDQVpmZU2B?=
 =?us-ascii?Q?t5UgSCihblxEzh98tTNHdmjlzhVAM6/xNPxAU9D/pJWaCT6mJNQFIeCIW5Xf?=
 =?us-ascii?Q?cWVrOzmTL92PAiZY21MeWt2CpinObwQ2oisNDigE18l1TUprZRBlkzptfrGa?=
 =?us-ascii?Q?0x6xn1k/wrCGnjaBg/Z+hrouI+6OHFEiQ7tRTKzTYVt80gMDGLUSp1wQboFG?=
 =?us-ascii?Q?MwLQC8weJL2xZ22fVYFZXzw+LDM/9HQ4xr3mZZsli5Kig4Xdv0zrYXLKjQfA?=
 =?us-ascii?Q?fojYn1GU6nDkvsYqS4EXmj+wXJ3H9i+w+SdH33y4l07MO0eASSK7LIDONgdR?=
 =?us-ascii?Q?IJAz1mCNCKGa6IJH1G3oaYRd5RJHSW5d3AfS5tB3WJvK+mSMIjTRj4OEgzPO?=
 =?us-ascii?Q?DYvLmg/7xlX5cPorAcPAJRWEjo3on0zdwFzN/9HQkwcg9qW42Ncc2UBHSNb5?=
 =?us-ascii?Q?ms7yY7snhbngG+eLTQLKdqyy?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 7c7aa21b-271e-4ef8-90b1-08d8d53b6a06
X-MS-Exchange-CrossTenant-AuthSource: BYAPR10MB2999.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2021 01:04:03.2986
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: JdpvoM8L5Zvyw28JGtKaPqVwrA4OwNccI9WWfZe16fVoF1WQqjkX/vkdIUHAdEgPhTJ8M0TF7WxctKLM+mj/BQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR10MB2614
X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9900 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 spamscore=0 mlxscore=0
 phishscore=0 adultscore=0 bulkscore=0 mlxlogscore=999 suspectscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000
 definitions=main-2102200003
X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9900 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 impostorscore=0 phishscore=0
 mlxlogscore=999 malwarescore=0 clxscore=1011 suspectscore=0
 lowpriorityscore=0 bulkscore=0 adultscore=0 priorityscore=1501 mlxscore=0
 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2009150000 definitions=main-2102200003
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Feb 16, 2021 at 08:09:54PM -0800, Ben Widawsky wrote:
> The CXL memory device send interface will have a number of supported
> commands. The raw command is not such a command. Raw commands allow
> userspace to send a specified opcode to the underlying hardware and
> bypass all driver checks on the command. The primary use for this
> command is to [begrudgingly] allow undocumented vendor specific hardware
> commands.
> 
> While not the main motivation, it also allows prototyping new hardware
> commands without a driver patch and rebuild.
> 
> While this all sounds very powerful it comes with a couple of caveats:
> 1. Bug reports using raw commands will not get the same level of
>    attention as bug reports using supported commands (via taint).
> 2. Supported commands will be rejected by the RAW command.
> 
> With this comes new debugfs knob to allow full access to your toes with
> your weapon of choice.
> 
> Cc: Ariel Sibley <Ariel.Sibley@microchip.com>
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com> (v2)
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>