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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5eca8df2a38sm4234612e0c.16.2026.11.05.06.59.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Nov 2026 06:59:53 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xOywS-00000002o7b-2oaN; Thu, 05 Nov 2026 10:59:52 -0400 Date: Thu, 5 Nov 2026 10:59:52 -0400 From: Jason Gunthorpe To: Andrew Lunn Cc: Robin Murphy , Greg Kroah-Hartman , Leon Romanovsky , "Rafael J. Wysocki" , Danilo Krummrich , Dmitry Torokhov , Heiner Kallweit , Russell King , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Johannes Berg , Jonathan Corbet , Shuah Khan , Randy Dunlap , Bjorn Helgaas , "Joerg Roedel (AMD)" , Suravee Suthikulpanit , Vasant Hegde , Will Deacon , David Woodhouse , Lu Baolu , Johan Hovold , Eric Dumazet , Marcel Holtmann , Luiz Augusto von Dentz , Nipun Gupta , Nikhil Agarwal , Pieter Jansen van Vuuren , linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, linux-input@vger.kernel.org, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-usb@vger.kernel.org, linux-bluetooth@vger.kernel.org, linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, iommu@lists.linux.dev Subject: Re: [PATCH 10/17] driver core: Expose device trust authorization through sysfs Message-ID: <20261105145952.GA663069@ziepe.ca> References: <20261105-device-trust-core-v1-0-1e536825b4eb@nvidia.com> <20261105-device-trust-core-v1-10-1e536825b4eb@nvidia.com> <2026110514-bunkhouse-handset-6a3a@gregkh> <20261105132729.GB8298@unreal> <2026110535-engulf-precut-cf10@gregkh> <9d896ebb-6892-4cac-a7c5-41def47f0be0@arm.com> <54c9476c-9f76-4ea1-a73a-c9937d6b463c@lunn.ch> X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54c9476c-9f76-4ea1-a73a-c9937d6b463c@lunn.ch> On Thu, Nov 05, 2026 at 03:43:53PM +0100, Andrew Lunn wrote: > > Yup, and that's true even in the PCI TDISP case - there's a major amount of > > "communication" and "configuration" involved in that. The principle which > > should (hopefully) generalise is that a bus/host controller driver can > > always interrogate its child device to perform whatever attestation and > > general configuration is appropriate, but we won't hand off any _control_ of > > that device to a specific device driver (nor enable potentially-impactful > > bus-level features like DMA, interrupts, etc. if relevant) without the > > requisite agreement between the bus code and the user. > > Maybe it would be good to list subsystems which the bus driver can > use, and cannot use. > > You list interrupts as potentially being dangerous. What about reset > controllers, GPIOs, regulators? At least in the embedded world, the > bus driver might need to enable power, set a clock ticking, and take > the device out of reset via a GPIO, before the device pops into > existence and will enumerate on the bus. > > I don't see why interrupts are dangerous, which makes it hard for me > to determine if GPIOs and clocks, and regulators are also dangerous? IMHO we shouldn't try to over think this. The overall point is to give the userspace a place to inject policy. Bus drivers should try as hard as they can to contain their child devices. Like PCIE should activate the iommu, disable ATS. USB should limit the messages it exchanges, and so on. When userspace accepts the bus driver it also accepts its containment capability. So if it accepts one that uses gpio, etc then that's fine. We are not the point of trying to describe what threat models various kernel drivers can support. Userspace has to figure that out on their own. Jason