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

Jens Wiklander
2025-03-05T13:06:42Z

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.

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