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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id a1e0cc1a2514c-998d9a9ca31sm3266318241.10.2026.11.04.16.49.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 16:49:35 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xOlfb-00000000cqL-0257; Wed, 04 Nov 2026 20:49:35 -0400 Date: Wed, 4 Nov 2026 20:49:34 -0400 From: Jason Gunthorpe To: Jacob Pan Cc: "Aneesh Kumar K.V (Arm)" , iommu@lists.linux.dev, Alex Williamson , Alexey Kardashevskiy , Bjorn Helgaas , Catalin Marinas , Joerg Roedel , Jonathan Cameron , Jonathan Hunter , Kevin Tian , Krishna Reddy , Lukas Wunner , Nicolin Chen , Robin Murphy , Samuel Ortiz , Shameer Kolothum , Steven Price , Suravee Suthikulpanit , Suzuki K Poulose , Thierry Reding , Vasant Hegde , Will Deacon , Xu Yilun , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-tegra@vger.kernel.org Subject: Re: [PATCH v8 12/15] iommufd/viommu: Allow PCI TSM backends to provide vIOMMU operations Message-ID: <20261105004934.GE3889730@ziepe.ca> References: <20261104161632.3547423-1-aneesh.kumar@kernel.org> <20261104161632.3547423-13-aneesh.kumar@kernel.org> <20261104152351.00002565@linux.microsoft.com> X-Mailing-List: linux-coco@lists.linux.dev 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: <20261104152351.00002565@linux.microsoft.com> On Wed, Nov 04, 2026 at 03:23:51PM -0800, Jacob Pan wrote: > I am thinking MSHV/pKVM can register an assignment-only tsm_dev to > leverage this? Could PCI/TSM support this role without device-security? It is certainly not what TSM was originally imagined for, but with our new arrangement, yah maybe so? TSM basically just becomes this weird overlay driver on the PCI device that does stuff. Some of the stuff it might do: - Register an attestation subsystem device to do SPDM - Register to allow iommufd to create a viommu - Some status sysfs ? - ?? It all seems separable and composable to me, so if you don't want to launch an attestation subsystem device because there is no SPDM then I think that might be OK? Another option would be to somehow obtain the viommu from the kvm file descriptor and rely on the fd to handle the module pinning/etc. I don't know how to do that nicely with the way the modules work though.. Jason