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From: Dan Williams <dan.j.williams@intel.com>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
	linux-cxl@vger.kernel.org, Linux PCI <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <helgaas@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Ben Widawsky <ben.widawsky@intel.com>,
	Chris Browy <cbrowy@avery-design.com>,
	Linux ACPI <linux-acpi@vger.kernel.org>,
	"Schofield, Alison" <alison.schofield@intel.com>,
	Vishal L Verma <vishal.l.verma@intel.com>,
	Linuxarm <linuxarm@huawei.com>, Fangjian <f.fangjian@huawei.com>,
	Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [RFC PATCH v3 2/4] PCI/doe: Add Data Object Exchange support
Date: Wed, 19 May 2021 17:16:28 -0700
Message-ID: <CAPcyv4hRcdw1N2b1WsVOLqDwZQSt6o=fQsn=VPtA5gpJFY-Qgw@mail.gmail.com> (raw)
In-Reply-To: <CAPcyv4hCCqEPzGKh4hyjHEBE3jDn9iTA_WUOZMFptHKrX-2J_A@mail.gmail.com>

On Wed, May 19, 2021 at 4:51 PM Dan Williams <dan.j.williams@intel.com> wrote:
[..]
> > The short answer is that lock requirement, in the above note, rules
> > out safe direct userspace use of the DOE (unless we can tell the kernel
> > is not going to ever use it).
>
> Linux has the mitigation for that situation defined already. It's the
> mechanism for /dev/mem and pci-mmap exclusion: disable the driver to
> enable unfettered userspace access (modulo kernel-lockdown is
> disabled).
>

Note that when I say "driver" here, it need not necessarily be the
cxl_pci driver for the memory expander. For example, DOE functionality
could be handled by an aux-bus device+driver where that can be
unloaded without taking down the rest of the CXL driver.

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 16:54 [RFC PATCH v3 0/4] PCI Data Object Exchange support + CXL CDAT Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 1/4] PCI: Add vendor ID for the PCI SIG Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 2/4] PCI/doe: Add Data Object Exchange support Jonathan Cameron
2021-05-06 21:59   ` Ira Weiny
2021-05-11 16:50     ` Jonathan Cameron
2021-05-13 21:20       ` Dan Williams
2021-05-14  8:47         ` Jonathan Cameron
2021-05-14 11:15           ` Lorenzo Pieralisi
2021-05-14 12:39             ` Jonathan Cameron
2021-05-14 18:37           ` Dan Williams
2021-05-17  8:40             ` Jonathan Cameron
2021-05-17  8:51               ` Greg KH
2021-05-17 17:21               ` Dan Williams
2021-05-18 10:04                 ` Jonathan Cameron
2021-05-19 14:18                   ` Dan Williams
2021-05-19 15:11                     ` Jonathan Cameron
2021-05-19 15:29                       ` Dan Williams
2021-05-19 16:20                         ` Jonathan Cameron
2021-05-19 16:33                           ` Jonathan Cameron
2021-05-19 16:53                             ` Dan Williams
2021-05-19 17:00                               ` Jonathan Cameron
2021-05-19 19:20                                 ` Dan Williams
2021-05-19 20:18                                   ` Jonathan Cameron
2021-05-19 23:51                                     ` Dan Williams
2021-05-20  0:16                                       ` Dan Williams [this message]
2021-05-20  8:22                                       ` Jonathan Cameron
2021-05-07  9:36   ` Jonathan Cameron
2021-05-07 23:10   ` Bjorn Helgaas
2021-05-12 12:44     ` Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 3/4] cxl/mem: Add CDAT table reading from DOE Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 4/4] cxl/mem: Add a debug parser for CDAT commands Jonathan Cameron

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