[Linaro-mm-sig] Re: [PATCH v12 0/9] TEE subsystem for protected dma-buf allocations

Hi,

On Thu, Sep 11, 2025 at 3:50 PM Jens Wiklander jens.wiklander@linaro.org wrote:

Hi,

This patch set allocates the protected DMA-bufs from a DMA-heap instantiated from the TEE subsystem.

The TEE subsystem handles the DMA-buf allocations since it is the TEE (OP-TEE, AMD-TEE, TS-TEE, or perhaps a future QTEE) which sets up the protection for the memory used for the DMA-bufs.

The DMA-heap uses a protected memory pool provided by the backend TEE driver, allowing it to choose how to allocate the protected physical memory.

The allocated DMA-bufs must be imported with a new TEE_IOC_SHM_REGISTER_FD before they can be passed as arguments when requesting services from the secure world.

Three use-cases (Secure Video Playback, Trusted UI, and Secure Video Recording) have been identified so far to serve as examples of what can be expected. The use-cases have predefined DMA-heap names, "protected,secure-video", "protected,trusted-ui", and "protected,secure-video-record". The backend driver registers protected memory pools for the use-cases it supports.

Each use-case has its own protected memory pool since different use-cases require isolation from different parts of the system. A protected memory pool can be based on a static carveout instantiated while probing the TEE backend driver, or dynamically allocated from CMA (dma_alloc_pages()) and made protected as needed by the TEE.

After the small update from v11, I'm picking up this and aiming for the next merge window.

Thanks, Jens

This can be tested on a RockPi 4B+ with the following steps: repo init -u https://github.com/jenswi-linaro/manifest.git -m rockpi4.xml \ -b prototype/sdp-v12 repo sync -j8 cd build make toolchains -j$(nproc) make all -j$(nproc) # Copy ../out/rockpi4.img to an SD card and boot the RockPi from that # Connect a monitor to the RockPi # login and at the prompt: gst-launch-1.0 videotestsrc ! \ aesenc key=1f9423681beb9a79215820f6bda73d0f \ iv=e9aa8e834d8d70b7e0d254ff670dd718 serialize-iv=true ! \ aesdec key=1f9423681beb9a79215820f6bda73d0f ! \ kmssink

The aesdec module has been hacked to use an OP-TEE TA to decrypt the stream into protected DMA-bufs which are consumed by the kmssink.

The primitive QEMU tests from previous patch sets can be tested on RockPi in the same way using: xtest --sdp-basic

The primitive tests are tested on QEMU with the following steps: repo init -u https://github.com/jenswi-linaro/manifest.git -m qemu_v8.xml \ -b prototype/sdp-v12 repo sync -j8 cd build make toolchains -j$(nproc) make SPMC_AT_EL=1 all -j$(nproc) make SPMC_AT_EL=1 run-only # login and at the prompt: xtest --sdp-basic

The SPMC_AT_EL=1 parameter configures the build with FF-A and an SPMC at S-EL1 inside OP-TEE. The parameter can be changed to SPMC_AT_EL=n to test without FF-A using the original SMC ABI instead. Please remember to do %make arm-tf-clean for TF-A to be rebuilt properly using the new configuration.

https://optee.readthedocs.io/en/latest/building/prerequisites.html list dependencies required to build the above.

The primitive tests are pretty basic, mostly checking that a Trusted Application in the secure world can access and manipulate the memory. There are also some negative tests for out of bounds buffers, etc.

Thanks, Jens

Changes since V11:

• In "dma-buf: dma-heap: export declared functions":
  • use EXPORT_SYMBOL_NS_GPL()
  • Added TJ's R-B and Sumit's Ack
• In "tee: implement protected DMA-heap", import the namespaces "DMA_BUF" and "DMA_BUF_HEAP" as needed.

Changes since V10:

• Changed the new ABI OPTEE_MSG_CMD_GET_PROTMEM_CONFIG to report a list of u32 memory attributes instead of u16 endpoints to make room for both endpoint and access permissions in each entry.
• In "tee: new ioctl to a register tee_shm from a dmabuf file descriptor", remove the unused path for DMA-bufs allocated by other means than the on in the TEE SS.
• In "tee: implement protected DMA-heap", handle unloading of the backend driver module implementing the heap. The heap is reference counted and also calls tee_device_get() to guarantee that the module remains available while the heap is instantiated.
• In "optee: support protected memory allocation", use dma_coerce_mask_and_coherent() instead of open-coding the function.
• Added Sumit's R-B to
  • "optee: smc abi: dynamic protected memory allocation"
  • "optee: FF-A: dynamic protected memory allocation"
  • "optee: support protected memory allocation"
  • "tee: implement protected DMA-heap"
  • "dma-buf: dma-heap: export declared functions"

Changes since V9:

• Adding Sumit's R-B to "optee: sync secure world ABI headers"
• Update commit message as requested for "dma-buf: dma-heap: export declared functions".
• In "tee: implement protected DMA-heap":
  • add the hidden config option TEE_DMABUF_HEAPS to tell if the TEE subsystem can support DMA heaps
  • add a pfn_valid() to check that the passed physical address can be used by __pfn_to_page() and friends
  • remove the memremap() call, the caller is should do that instead if needed
• In "tee: add tee_shm_alloc_dma_mem()" guard the calls to dma_alloc_pages() and dma_free_pages() with TEE_DMABUF_HEAPS to avoid linking errors in some configurations
• In "optee: support protected memory allocation":
  • add the hidden config option OPTEE_STATIC_PROTMEM_POOL to tell if the driver can support a static protected memory pool
  • optee_protmem_pool_init() is slightly refactored to make the patches that follow easier
  • Call devm_memremap() before calling tee_protmem_static_pool_alloc()

Changes since V8:

• Using dma_alloc_pages() instead of cma_alloc() so the direct dependency on CMA can be removed together with the patches "cma: export cma_alloc() and cma_release()" and "dma-contiguous: export dma_contiguous_default_area". The patch
• Renaming the patch "tee: add tee_shm_alloc_cma_phys_mem()" to "tee: add tee_shm_alloc_dma_mem()"
• Setting DMA mask for the OP-TEE TEE device based on input from the secure world instead of relying on the parent device so following patches are removed: "tee: tee_device_alloc(): copy dma_mask from parent device" and "optee: pass parent device to tee_device_alloc()".
• Adding Sumit Garg's R-B to "tee: refactor params_from_user()"
• In the patch "tee: implement protected DMA-heap", map the physical memory passed to tee_protmem_static_pool_alloc().

Changes since V7:

• Adding "dma-buf: dma-heap: export declared functions", "cma: export cma_alloc() and cma_release()", and "dma-contiguous: export dma_contiguous_default_area" to export the symbols needed to keep the TEE subsystem as a load module.
• Removing CONFIG_TEE_DMABUF_HEAP and CONFIG_TEE_CMA since they aren't needed any longer.
• Addressing review comments in "optee: sync secure world ABI headers"
• Better align protected memory pool initialization between the smc-abi and ffa-abi parts of the optee driver.
• Removing the patch "optee: account for direction while converting parameters"

Changes since V6:

• Restricted memory is now known as protected memory since to use the same term as https://docs.vulkan.org/guide/latest/protected.html. Update all patches to consistently use protected memory.
• In "tee: implement protected DMA-heap" add the hidden config option TEE_DMABUF_HEAP to tell if the DMABUF_HEAPS functions are available for the TEE subsystem
• Adding "tee: refactor params_from_user()", broken out from the patch "tee: new ioctl to a register tee_shm from a dmabuf file descriptor"
• For "tee: new ioctl to a register tee_shm from a dmabuf file descriptor":
  • Update commit message to mention protected memory
  • Remove and open code tee_shm_get_parent_shm() in param_from_user_memref()
• In "tee: add tee_shm_alloc_cma_phys_mem" add the hidden config option TEE_CMA to tell if the CMA functions are available for the TEE subsystem
• For "tee: tee_device_alloc(): copy dma_mask from parent device" and "optee: pass parent device to tee_device_alloc", added Reviewed-by: Sumit Garg sumit.garg@kernel.org

Changes since V5:

• Removing "tee: add restricted memory allocation" and "tee: add TEE_IOC_RSTMEM_FD_INFO"
• Adding "tee: implement restricted DMA-heap", "tee: new ioctl to a register tee_shm from a dmabuf file descriptor", "tee: add tee_shm_alloc_cma_phys_mem()", "optee: pass parent device to tee_device_alloc()", and "tee: tee_device_alloc(): copy dma_mask from parent device"
• The two TEE driver OPs "rstmem_alloc()" and "rstmem_free()" are replaced with a struct tee_rstmem_pool abstraction.
• Replaced the the TEE_IOC_RSTMEM_ALLOC user space API with the DMA-heap API

Changes since V4:

• Adding the patch "tee: add TEE_IOC_RSTMEM_FD_INFO" needed by the GStreamer demo
• Removing the dummy CPU access and mmap functions from the dma_buf_ops
• Fixing a compile error in "optee: FF-A: dynamic restricted memory allocation" reported by kernel test robot lkp@intel.com

Changes since V3:

• Make the use_case and flags field in struct tee_shm u32's instead of u16's
• Add more description for TEE_IOC_RSTMEM_ALLOC in the header file
• Import namespace DMA_BUF in module tee, reported by lkp@intel.com
• Added a note in the commit message for "optee: account for direction while converting parameters" why it's needed
• Factor out dynamic restricted memory allocation from "optee: support restricted memory allocation" into two new commits "optee: FF-A: dynamic restricted memory allocation" and "optee: smc abi: dynamic restricted memory allocation"
• Guard CMA usage with #ifdef CONFIG_CMA, effectively disabling dynamic restricted memory allocate if CMA isn't configured

Changes since the V2 RFC:

• Based on v6.12
• Replaced the flags for SVP and Trusted UID memory with a u32 field with unique id for each use case
• Added dynamic allocation of restricted memory pools
• Added OP-TEE ABI both with and without FF-A for dynamic restricted memory
• Added support for FF-A with FFA_LEND

Changes since the V1 RFC:

• Based on v6.11
• Complete rewrite, replacing the restricted heap with TEE_IOC_RSTMEM_ALLOC

Changes since Olivier's post [2]:

• Based on Yong Wu's post [1] where much of dma-buf handling is done in the generic restricted heap
• Simplifications and cleanup
• New commit message for "dma-buf: heaps: add Linaro restricted dmabuf heap support"
• Replaced the word "secure" with "restricted" where applicable

Etienne Carriere (1): tee: new ioctl to a register tee_shm from a dmabuf file descriptor

Jens Wiklander (8): optee: sync secure world ABI headers dma-buf: dma-heap: export declared functions tee: implement protected DMA-heap tee: refactor params_from_user() tee: add tee_shm_alloc_dma_mem() optee: support protected memory allocation optee: FF-A: dynamic protected memory allocation optee: smc abi: dynamic protected memory allocation

drivers/dma-buf/dma-heap.c | 4 + drivers/tee/Kconfig | 5 + drivers/tee/Makefile | 1 + drivers/tee/optee/Kconfig | 5 + drivers/tee/optee/Makefile | 1 + drivers/tee/optee/core.c | 7 + drivers/tee/optee/ffa_abi.c | 146 ++++++++- drivers/tee/optee/optee_ffa.h | 27 +- drivers/tee/optee/optee_msg.h | 84 ++++- drivers/tee/optee/optee_private.h | 15 +- drivers/tee/optee/optee_smc.h | 37 ++- drivers/tee/optee/protmem.c | 335 ++++++++++++++++++++ drivers/tee/optee/smc_abi.c | 141 ++++++++- drivers/tee/tee_core.c | 158 +++++++--- drivers/tee/tee_heap.c | 500 ++++++++++++++++++++++++++++++ drivers/tee/tee_private.h | 14 + drivers/tee/tee_shm.c | 157 +++++++++- include/linux/tee_core.h | 59 ++++ include/linux/tee_drv.h | 10 + include/uapi/linux/tee.h | 31 ++ 20 files changed, 1670 insertions(+), 67 deletions(-) create mode 100644 drivers/tee/optee/protmem.c create mode 100644 drivers/tee/tee_heap.c

base-commit: c17b750b3ad9f45f2b6f7e6f7f4679844244f0b9

2.43.0