Re: [PATCH v5 04/10] PCI/TSM: Authenticate devices via platform TSM

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Dan Williams <dan.j.williams@intel.com> writes:

> The PCIe 7.0 specification, section 11, defines the Trusted Execution
> Environment (TEE) Device Interface Security Protocol (TDISP).  This
> protocol definition builds upon Component Measurement and Authentication
> (CMA), and link Integrity and Data Encryption (IDE). It adds support for
> assigning devices (PCI physical or virtual function) to a confidential VM
> such that the assigned device is enabled to access guest private memory
> protected by technologies like Intel TDX, AMD SEV-SNP, RISCV COVE, or ARM
> CCA.
>
> The "TSM" (TEE Security Manager) is a concept in the TDISP specification
> of an agent that mediates between a "DSM" (Device Security Manager) and
> system software in both a VMM and a confidential VM. A VMM uses TSM ABIs
> to setup link security and assign devices. A confidential VM uses TSM
> ABIs to transition an assigned device into the TDISP "RUN" state and
> validate its configuration. From a Linux perspective the TSM abstracts
> many of the details of TDISP, IDE, and CMA. Some of those details leak
> through at times, but for the most part TDISP is an internal
> implementation detail of the TSM.
>
> CONFIG_PCI_TSM adds an "authenticated" attribute and "tsm/" subdirectory
> to pci-sysfs. Consider that the TSM driver may itself be a PCI driver.
> Userspace can watch for the arrival of a "TSM" device,
> /sys/class/tsm/tsm0/uevent KOBJ_CHANGE, to know when the PCI core has
> initialized TSM services.
>
> The operations that can be executed against a PCI device are split into
> two mutually exclusive operation sets, "Link" and "Security" (struct
> pci_tsm_{link,security}_ops). The "Link" operations manage physical link
> security properties and communication with the device's Device Security
> Manager firmware. These are the host side operations in TDISP. The
> "Security" operations coordinate the security state of the assigned
> virtual device (TDI). These are the guest side operations in TDISP. Only
> link management operations are defined at this stage and placeholders
> provided for the security operations.
>
> The locking allows for multiple devices to be executing commands
> simultaneously, one outstanding command per-device and an rwsem
> synchronizes the implementation relative to TSM
> registration/unregistration events.
>
> Thanks to Wu Hao for his work on an early draft of this support.
>
> Cc: Lukas Wunner <lukas@wunner.de>
> Cc: Samuel Ortiz <sameo@rivosinc.com>
> Cc: Alexey Kardashevskiy <aik@amd.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Co-developed-by: Xu Yilun <yilun.xu@linux.intel.com>
> Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

you dropped pci_tsm_doe_transfer from an earlier version of this patch
in this series. Any reason for that?

-aneesh