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>,
Jon Masters <jcm@jonmasters.org>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Randy Dunlap <rdunlap@infradead.org>,
daniel.lll@alibaba-inc.com,
"John Groves (jgroves)" <jgroves@micron.com>,
"Kelley, Sean V" <sean.v.kelley@intel.com>
Subject: Re: [PATCH 09/14] cxl/mem: Add a "RAW" send command
Date: Mon, 1 Feb 2021 13:24:00 -0500 [thread overview]
Message-ID: <20210201182400.GK197521@fedora> (raw)
In-Reply-To: <20210130002438.1872527-10-ben.widawsky@intel.com>
On Fri, Jan 29, 2021 at 04:24:33PM -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. This is useful for a couple of
> usecases, mainly:
> 1. Undocumented vendor specific hardware commands
> 2. Prototyping new hardware commands not yet supported by the driver
This sounds like a recipe for ..
In case you really really want this may I recommend you do two things:
- Wrap this whole thing with #ifdef
CONFIG_CXL_DEBUG_THIS_WILL_DESTROY_YOUR_LIFE
(or something equivalant to make it clear this should never be
enabled in production kernels).
- Add a nice big fat printk in dmesg telling the user that they
are creating a unstable parallel universe that will lead to their
blood pressure going sky-high, or perhaps something more professional
sounding.
- Rethink this. Do you really really want to encourage vendors
to use this raw API instead of them using the proper APIs?
>
> 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.
Problem is that debugfs is no longer "debug" but is enabled in
production kernel.
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WARNING: multiple messages have this Message-ID (diff)
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>,
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>,
daniel.lll@alibaba-inc.com,
"John Groves (jgroves)" <jgroves@micron.com>,
"Kelley, Sean V" <sean.v.kelley@intel.com>
Subject: Re: [PATCH 09/14] cxl/mem: Add a "RAW" send command
Date: Mon, 1 Feb 2021 13:24:00 -0500 [thread overview]
Message-ID: <20210201182400.GK197521@fedora> (raw)
In-Reply-To: <20210130002438.1872527-10-ben.widawsky@intel.com>
On Fri, Jan 29, 2021 at 04:24:33PM -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. This is useful for a couple of
> usecases, mainly:
> 1. Undocumented vendor specific hardware commands
> 2. Prototyping new hardware commands not yet supported by the driver
This sounds like a recipe for ..
In case you really really want this may I recommend you do two things:
- Wrap this whole thing with #ifdef
CONFIG_CXL_DEBUG_THIS_WILL_DESTROY_YOUR_LIFE
(or something equivalant to make it clear this should never be
enabled in production kernels).
- Add a nice big fat printk in dmesg telling the user that they
are creating a unstable parallel universe that will lead to their
blood pressure going sky-high, or perhaps something more professional
sounding.
- Rethink this. Do you really really want to encourage vendors
to use this raw API instead of them using the proper APIs?
>
> 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.
Problem is that debugfs is no longer "debug" but is enabled in
production kernel.
next prev parent reply other threads:[~2021-02-01 18:26 UTC|newest]
Thread overview: 193+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-30 0:24 [PATCH 00/14] CXL 2.0 Support Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 01/14] cxl/mem: Introduce a driver for CXL-2.0-Type-3 endpoints Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 23:51 ` David Rientjes
2021-01-30 23:51 ` David Rientjes
2021-02-01 17:21 ` Jonathan Cameron
2021-02-01 17:21 ` Jonathan Cameron
2021-02-01 17:34 ` Konrad Rzeszutek Wilk
2021-02-01 17:34 ` Konrad Rzeszutek Wilk
2021-02-02 17:58 ` Christoph Hellwig
2021-02-02 17:58 ` Christoph Hellwig
2021-02-02 18:00 ` Christoph Hellwig
2021-02-02 18:00 ` Christoph Hellwig
2021-01-30 0:24 ` [PATCH 02/14] cxl/mem: Map memory device registers Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 23:51 ` David Rientjes
2021-01-30 23:51 ` David Rientjes
2021-02-01 16:46 ` Ben Widawsky
2021-02-01 16:46 ` Ben Widawsky
2021-02-01 18:19 ` Jonathan Cameron
2021-02-01 18:19 ` Jonathan Cameron
2021-02-01 17:36 ` Konrad Rzeszutek Wilk
2021-02-01 17:36 ` Konrad Rzeszutek Wilk
2021-02-02 18:04 ` Christoph Hellwig
2021-02-02 18:04 ` Christoph Hellwig
2021-02-02 18:31 ` Ben Widawsky
2021-02-02 18:31 ` Ben Widawsky
2021-02-03 17:12 ` Christoph Hellwig
2021-02-03 17:12 ` Christoph Hellwig
2021-01-30 0:24 ` [PATCH 03/14] cxl/mem: Find device capabilities Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 23:51 ` David Rientjes
2021-01-30 23:51 ` David Rientjes
2021-02-01 16:53 ` Ben Widawsky
2021-02-01 16:53 ` Ben Widawsky
2021-02-01 21:51 ` David Rientjes
2021-02-01 21:51 ` David Rientjes
2021-02-01 21:58 ` Ben Widawsky
2021-02-01 21:58 ` Ben Widawsky
2021-02-01 22:23 ` David Rientjes
2021-02-01 22:23 ` David Rientjes
2021-02-01 22:28 ` Ben Widawsky
2021-02-01 22:28 ` Ben Widawsky
2021-02-01 22:33 ` Ben Widawsky
2021-02-01 22:33 ` Ben Widawsky
2021-02-01 22:45 ` David Rientjes
2021-02-01 22:45 ` David Rientjes
2021-02-01 22:50 ` Ben Widawsky
2021-02-01 22:50 ` Ben Widawsky
2021-02-01 23:09 ` David Rientjes
2021-02-01 23:09 ` David Rientjes
2021-02-01 23:17 ` Ben Widawsky
2021-02-01 23:17 ` Ben Widawsky
2021-02-01 23:58 ` David Rientjes
2021-02-01 23:58 ` David Rientjes
2021-02-02 0:11 ` Ben Widawsky
2021-02-02 0:11 ` Ben Widawsky
2021-02-02 0:14 ` Dan Williams
2021-02-02 0:14 ` Dan Williams
2021-02-02 1:09 ` David Rientjes
2021-02-02 1:09 ` David Rientjes
2021-02-01 22:02 ` Dan Williams
2021-02-01 22:02 ` Dan Williams
2021-02-01 17:41 ` Konrad Rzeszutek Wilk
2021-02-01 17:41 ` Konrad Rzeszutek Wilk
2021-02-01 17:50 ` Ben Widawsky
2021-02-01 17:50 ` Ben Widawsky
2021-02-01 18:08 ` Konrad Rzeszutek Wilk
2021-02-01 18:08 ` Konrad Rzeszutek Wilk
2021-02-02 18:10 ` Christoph Hellwig
2021-02-02 18:10 ` Christoph Hellwig
2021-02-02 18:24 ` Ben Widawsky
2021-02-02 18:24 ` Ben Widawsky
2021-02-03 17:15 ` Christoph Hellwig
2021-02-03 17:15 ` Christoph Hellwig
2021-02-03 17:23 ` Ben Widawsky
2021-02-03 17:23 ` Ben Widawsky
2021-02-03 21:23 ` Dan Williams
2021-02-03 21:23 ` Dan Williams
2021-02-04 7:16 ` Christoph Hellwig
2021-02-04 7:16 ` Christoph Hellwig
2021-02-04 15:29 ` Ben Widawsky
2021-02-04 15:29 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 04/14] cxl/mem: Implement polled mode mailbox Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 23:51 ` David Rientjes
2021-01-30 23:51 ` David Rientjes
2021-02-01 20:00 ` Dan Williams
2021-02-01 20:00 ` Dan Williams
2021-02-02 22:57 ` Ben Widawsky
2021-02-02 22:57 ` Ben Widawsky
2021-02-02 23:54 ` Dan Williams
2021-02-02 23:54 ` Dan Williams
2021-02-03 0:54 ` Ben Widawsky
2021-02-03 0:54 ` Ben Widawsky
2021-02-02 22:50 ` Ben Widawsky
2021-02-02 22:50 ` Ben Widawsky
2021-02-01 17:54 ` Konrad Rzeszutek Wilk
2021-02-01 17:54 ` Konrad Rzeszutek Wilk
2021-02-01 19:13 ` Ben Widawsky
2021-02-01 19:13 ` Ben Widawsky
2021-02-01 19:28 ` Dan Williams
2021-02-01 19:28 ` Dan Williams
2021-02-04 21:53 ` [EXT] " John Groves (jgroves)
2021-02-04 22:24 ` Ben Widawsky
2021-02-04 22:24 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 05/14] cxl/mem: Register CXL memX devices Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 0:31 ` Dan Williams
2021-01-30 0:31 ` Dan Williams
2021-01-30 23:52 ` David Rientjes
2021-01-30 23:52 ` David Rientjes
2021-02-01 17:10 ` Ben Widawsky
2021-02-01 17:10 ` Ben Widawsky
2021-02-01 21:53 ` David Rientjes
2021-02-01 21:53 ` David Rientjes
2021-02-01 21:55 ` Dan Williams
2021-02-01 21:55 ` Dan Williams
2021-02-02 18:13 ` Christoph Hellwig
2021-02-02 18:13 ` Christoph Hellwig
2021-01-30 0:24 ` [PATCH 06/14] cxl/mem: Add basic IOCTL interface Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-02-02 18:15 ` Christoph Hellwig
2021-02-02 18:15 ` Christoph Hellwig
2021-02-02 18:33 ` Ben Widawsky
2021-02-02 18:33 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 07/14] cxl/mem: Add send command Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-02-01 18:15 ` Konrad Rzeszutek Wilk
2021-02-01 18:15 ` Konrad Rzeszutek Wilk
2021-02-02 23:08 ` Ben Widawsky
2021-02-02 23:08 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 08/14] taint: add taint for direct hardware access Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-02-01 18:18 ` Konrad Rzeszutek Wilk
2021-02-01 18:18 ` Konrad Rzeszutek Wilk
2021-02-01 18:34 ` Ben Widawsky
2021-02-01 18:34 ` Ben Widawsky
2021-02-01 19:01 ` Dan Williams
2021-02-01 19:01 ` Dan Williams
2021-02-02 2:49 ` Konrad Rzeszutek Wilk
2021-02-02 2:49 ` Konrad Rzeszutek Wilk
2021-02-02 17:46 ` Dan Williams
2021-02-02 17:46 ` Dan Williams
2021-02-08 22:00 ` Dan Williams
2021-02-08 22:00 ` Dan Williams
2021-02-08 22:09 ` Kees Cook
2021-02-08 22:09 ` Kees Cook
2021-02-08 23:05 ` Ben Widawsky
2021-02-08 23:05 ` Ben Widawsky
2021-02-08 23:36 ` Dan Williams
2021-02-08 23:36 ` Dan Williams
2021-02-09 1:03 ` Dan Williams
2021-02-09 1:03 ` Dan Williams
2021-02-09 3:36 ` Ben Widawsky
2021-02-09 3:36 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 09/14] cxl/mem: Add a "RAW" send command Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-02-01 18:24 ` Konrad Rzeszutek Wilk [this message]
2021-02-01 18:24 ` Konrad Rzeszutek Wilk
2021-02-01 19:27 ` Ben Widawsky
2021-02-01 19:27 ` Ben Widawsky
2021-02-01 19:34 ` Konrad Rzeszutek Wilk
2021-02-01 19:34 ` Konrad Rzeszutek Wilk
2021-02-01 21:20 ` Dan Williams
2021-02-01 21:20 ` Dan Williams
2021-01-30 0:24 ` [PATCH 10/14] cxl/mem: Create concept of enabled commands Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 11/14] cxl/mem: Use CEL for enabling commands Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 12/14] cxl/mem: Add set of informational commands Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-01-30 0:24 ` [PATCH 13/14] cxl/mem: Add limited Get Log command (0401h) Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
2021-02-01 18:28 ` Konrad Rzeszutek Wilk
2021-02-01 18:28 ` Konrad Rzeszutek Wilk
2021-02-02 23:51 ` Ben Widawsky
2021-02-02 23:51 ` Ben Widawsky
2021-02-02 23:57 ` Dan Williams
2021-02-02 23:57 ` Dan Williams
2021-02-03 17:16 ` Ben Widawsky
2021-02-03 17:16 ` Ben Widawsky
2021-02-03 18:14 ` Konrad Rzeszutek Wilk
2021-02-03 18:14 ` Konrad Rzeszutek Wilk
2021-02-03 20:31 ` Dan Williams
2021-02-03 20:31 ` Dan Williams
2021-02-04 18:55 ` Ben Widawsky
2021-02-04 18:55 ` Ben Widawsky
2021-02-04 21:01 ` Dan Williams
2021-02-04 21:01 ` Dan Williams
2021-01-30 0:24 ` [PATCH 14/14] MAINTAINERS: Add maintainers of the CXL driver Ben Widawsky
2021-01-30 0:24 ` Ben Widawsky
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