Re: [PATCH v6 00/10] TEE subsystem for restricted dma-buf allocations

Jens Wiklander
2025-03-27T08:27:23Z

Hi,

On Wed, Mar 5, 2025 at 2:06 PM Jens Wiklander <jens.wiklander@linaro.org> wrote:
>
> Hi,
>
> This patch set allocates the restricted 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
> restrictions for the memory used for the DMA-bufs.
>
> The DMA-heap uses a restricted memory pool provided by the backend TEE
> driver, allowing it to choose how to allocate the restricted 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) has been identified so far to serve as examples of what can be
> expected. The use-cases has predefined DMA-heap names,
> "restricted,secure-video", "restricted,trusted-ui", and
> "restricted,secure-video-record". The backend driver registers restricted
> memory pools for the use-cases it supports.

When preparing a v7 of this patch set, I'll switch to "protected"
instead of "restricted" based on Nicolas Dufresne's comment [1],
unless someone objects.

[1] https://lore.kernel.org/lkml/32c29526416c07c37819aedabcbf1e562ee98bf2.camel@ndufresne.ca/

Cheers,
Jens

>
> Each use-case has it's own restricted memory pool since different use-cases
> requires isolation from different parts of the system. A restricted memory
> pool can be based on a static carveout instantiated while probing the TEE
> backend driver, or dynamically allocated from CMA and made restricted as
> needed by the TEE.
>
> 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-v6
> 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 restricted DMA-bufs which are consumed by the kmssink.
>
> The primitive QEMU tests from previous patch set can be tested on RockPi
> in the same way with:
> xtest --sdp-basic
>
> The primitive test 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-v6
> 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 into SPMC_AT_EL=n to test
> without FF-A using the original SMC ABI instead. Please remember to do
> %rm -rf ../trusted-firmware-a/build/qemu
> for TF-A to be rebuilt properly using the new configuration.
>
> https://optee.readthedocs.io/en/latest/building/prerequisites.html
> list dependencies needed to build the above.
>
> The 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 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 (9):
> tee: tee_device_alloc(): copy dma_mask from parent device
> optee: pass parent device to tee_device_alloc()
> optee: account for direction while converting parameters
> optee: sync secure world ABI headers
> tee: implement restricted DMA-heap
> tee: add tee_shm_alloc_cma_phys_mem()
> optee: support restricted memory allocation
> optee: FF-A: dynamic restricted memory allocation
> optee: smc abi: dynamic restricted memory allocation
>
> drivers/tee/Makefile | 1 +
> drivers/tee/optee/Makefile | 1 +
> drivers/tee/optee/call.c | 10 +-
> drivers/tee/optee/core.c | 1 +
> drivers/tee/optee/ffa_abi.c | 194 +++++++++++-
> drivers/tee/optee/optee_ffa.h | 27 +-
> drivers/tee/optee/optee_msg.h | 65 ++++-
> drivers/tee/optee/optee_private.h | 55 +++-
> drivers/tee/optee/optee_smc.h | 71 ++++-
> drivers/tee/optee/rpc.c | 31 +-
> drivers/tee/optee/rstmem.c | 329 +++++++++++++++++++++
> drivers/tee/optee/smc_abi.c | 190 ++++++++++--
> drivers/tee/tee_core.c | 147 +++++++---
> drivers/tee/tee_heap.c | 470 ++++++++++++++++++++++++++++++
> drivers/tee/tee_private.h | 7 +
> drivers/tee/tee_shm.c | 199 ++++++++++++-
> include/linux/tee_core.h | 67 +++++
> include/linux/tee_drv.h | 10 +
> include/uapi/linux/tee.h | 29 ++
> 19 files changed, 1781 insertions(+), 123 deletions(-)
> create mode 100644 drivers/tee/optee/rstmem.c
> create mode 100644 drivers/tee/tee_heap.c
>
>
> base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6
> --
> 2.43.0
>