From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jacob Pan <jacob.pan@linux.microsoft.com>
Cc: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>,
iommu@lists.linux.dev, Alex Williamson <alex@shazbot.org>,
Alexey Kardashevskiy <aik@amd.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Joerg Roedel <joro@8bytes.org>,
Jonathan Cameron <jic23@kernel.org>,
Jonathan Hunter <jonathanh@nvidia.com>,
Kevin Tian <kevin.tian@intel.com>,
Krishna Reddy <vdumpa@nvidia.com>, Lukas Wunner <lukas@wunner.de>,
Nicolin Chen <nicolinc@nvidia.com>,
Robin Murphy <robin.murphy@arm.com>,
Samuel Ortiz <sameo@rivosinc.com>,
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
Steven Price <steven.price@arm.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Thierry Reding <thierry.reding@kernel.org>,
Vasant Hegde <vasant.hegde@amd.com>,
Will Deacon <will@kernel.org>,
Xu Yilun <yilun.xu@linux.intel.com>,
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
Date: Wed, 4 Nov 2026 20:49:34 -0400 [thread overview]
Message-ID: <20261105004934.GE3889730@ziepe.ca> (raw)
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
next prev parent reply other threads:[~2026-11-05 0:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 16:16 [PATCH v8 00/15] iommufd: TSM-backed virtual IOMMUs for confidential guests Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 01/15] PCI/TSM: Move core code into its own directory Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 02/15] virt: coco: tsm: Remove the device from lookup before PCI teardown Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 03/15] virt: coco: tsm: Complete PCI registration before publishing the device Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 04/15] virt: coco: tsm: Require PCI operations when registering a TSM Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 05/15] iommufd/device: Associate KVM file pointer with iommufd_device Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 06/15] iommufd/device: Hold a KVM file reference for the device lifetime Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 07/15] iommufd/viommu: Keep a reference to the KVM file Aneesh Kumar K.V (Arm)
2026-11-04 16:35 ` Jacob Pan
2026-11-04 16:16 ` [PATCH v8 08/15] iommufd: Add a vDEVICE operation ioctl framework Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 09/15] PCI/TSM: Remove the legacy guest request interface Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 10/15] PCI/TSM: Add vIOMMU-bound device contexts Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 11/15] iommufd/viommu: Select vIOMMU operations before allocation Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 12/15] iommufd/viommu: Allow PCI TSM backends to provide vIOMMU operations Aneesh Kumar K.V (Arm)
2026-11-04 23:23 ` Jacob Pan
2026-11-05 0:49 ` Jason Gunthorpe [this message]
2026-11-04 16:16 ` [PATCH v8 13/15] iommufd/viommu: Allow vIOMMUs without a parent HWPT Aneesh Kumar K.V (Arm)
2026-11-04 19:03 ` Nicolin Chen
2026-11-04 19:31 ` Jason Gunthorpe
2026-11-04 16:16 ` [PATCH v8 14/15] PCI/TSM: Wait for device contexts before removing a DSM Aneesh Kumar K.V (Arm)
2026-11-04 16:16 ` [PATCH v8 15/15] PCI/TSM: Wait for users during unregister Aneesh Kumar K.V (Arm)
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