On Thu, Oct 17, 2024 at 12:46 PM Sumit Garg <sumit.garg@xxxxxxxxxx> wrote: > > Hi Jens, > > On Tue, 15 Oct 2024 at 15:47, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote: > > > > Hi, > > > > This patch set allocates the restricted DMA-bufs via the TEE subsystem. > > This a complete rewrite compared to the previous patch set [1], and other > > earlier proposals [2] and [3] with a separate restricted heap. > > > > The TEE subsystem handles the DMA-buf allocations since it is the TEE > > (OP-TEE, AMD-TEE, TS-TEE, or a future QTEE) which sets up the restrictions > > for the memory used for the DMA-bufs. > > Thanks for proposing this interface. IMHO, this solution will address > many concerns raised for the prior vendor specific DMA heaps approach > [1] as follows: > > 1. User-space interacting with the TEE subsystem for restricted memory > allocation makes it obvious that the returned DMA buf can't be > directly mapped by the CPU. > > 2. All the low level platform details gets abstracted out for > user-space regarding how the platform specific memory restriction > comes into play. > > 3. User-space doesn't have to deal with holding 2 DMA buffer > references, one after allocation from DMA heap and other for > communication with the TEE subsystem. > > 4. Allows for better co-ordination with other kernel subsystems > dealing with restricted DMA-bufs. > > [1] https://lore.kernel.org/linux-arm-kernel/20240515112308.10171-1-yong.wu@xxxxxxxxxxxx/ > > > > > I've added a new IOCTL, TEE_IOC_RSTMEM_ALLOC, to allocate the restricted > > DMA-bufs. This new IOCTL reaches the backend TEE driver, allowing it to > > choose how to allocate the restricted physical memory. > > > > TEE_IOC_RSTMEM_ALLOC is quite similar to TEE_IOC_SHM_ALLOC so it's tempting > > to extend TEE_IOC_SHM_ALLOC with two new flags > > TEE_IOC_SHM_FLAG_SECURE_VIDEO and TEE_IOC_SHM_FLAG_SECURE_TRUSTED_UI for > > the same feature. However, it might be a bit confusing since > > TEE_IOC_SHM_ALLOC only returns an anonymous file descriptor, but > > TEE_IOC_SHM_FLAG_SECURE_VIDEO and TEE_IOC_SHM_FLAG_SECURE_TRUSTED_UI would > > return a DMA-buf file descriptor instead. What do others think? > > I think it's better to keep it as a separate IOCTL given the primary > objective of buffer allocation and it's usage. Agreed. Thanks, Jens > > -Sumit > > > > > This can be tested on QEMU with the following steps: > > repo init -u https://github.com/jenswi-linaro/manifest.git -m qemu_v8.xml \ > > -b prototype/sdp-v2 > > repo sync -j8 > > cd build > > make toolchains -j4 > > make all -j$(nproc) > > make run-only > > # login and at the prompt: > > xtest --sdp-basic > > > > 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 > > > > [1] https://lore.kernel.org/lkml/20240830070351.2855919-1-jens.wiklander@xxxxxxxxxx/ > > [2] https://lore.kernel.org/dri-devel/20240515112308.10171-1-yong.wu@xxxxxxxxxxxx/ > > [3] https://lore.kernel.org/lkml/20220805135330.970-1-olivier.masse@xxxxxxx/ > > > > 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 > > > > Jens Wiklander (2): > > tee: add restricted memory allocation > > optee: support restricted memory allocation > > > > drivers/tee/Makefile | 1 + > > drivers/tee/optee/core.c | 21 ++++ > > drivers/tee/optee/optee_private.h | 6 + > > drivers/tee/optee/optee_smc.h | 35 ++++++ > > drivers/tee/optee/smc_abi.c | 45 ++++++- > > drivers/tee/tee_core.c | 33 ++++- > > drivers/tee/tee_private.h | 2 + > > drivers/tee/tee_rstmem.c | 200 ++++++++++++++++++++++++++++++ > > drivers/tee/tee_shm.c | 2 + > > drivers/tee/tee_shm_pool.c | 69 ++++++++++- > > include/linux/tee_core.h | 6 + > > include/linux/tee_drv.h | 9 ++ > > include/uapi/linux/tee.h | 33 ++++- > > 13 files changed, 455 insertions(+), 7 deletions(-) > > create mode 100644 drivers/tee/tee_rstmem.c > > > > -- > > 2.43.0 > >
