subsystem as a whole and in OP-TEE in particular.
Global Platform TEE specification [1] allows client applications
to register part of own memory as a shared buffer between
application and TEE. This allows fast zero-copy communication between
TEE and REE. But current implementation of TEE in Linux does not support
this feature.
Also, current implementation of OP-TEE transport uses fixed size
pre-shared buffer for all communications with OP-TEE OS. This is okay
in the most use cases. But this prevents use of OP-TEE in virtualized
environments, because:
a) We can't share the same buffer between different virtual machines
b) Physically contiguous memory as seen by VM can be non-contiguous
in reality (and as seen by OP-TEE OS) due to second stage of
MMU translation.
c) Size of this pre-shared buffer is limited.
So, first part of this pull request adds generic register/unregister
interface to tee subsystem. The second part adds necessary features into
OP-TEE driver, so it can use not only static pre-shared buffer, but
whole RAM to communicate with OP-TEE OS.
This change is backwards compatible allowing older secure world or
user space to work with newer kernels and vice versa.
[1] https://www.globalplatform.org/specificationsdevice.asp
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Merge tag 'tee-drv-dynamic-shm-for-v4.16' of https://git.linaro.org/people/jens.wiklander/linux-tee into next/drivers
Pull "tee dynamic shm for v4.16" from Jens Wiklander:
This pull request enables dynamic shared memory support in the TEE
subsystem as a whole and in OP-TEE in particular.
Global Platform TEE specification [1] allows client applications
to register part of own memory as a shared buffer between
application and TEE. This allows fast zero-copy communication between
TEE and REE. But current implementation of TEE in Linux does not support
this feature.
Also, current implementation of OP-TEE transport uses fixed size
pre-shared buffer for all communications with OP-TEE OS. This is okay
in the most use cases. But this prevents use of OP-TEE in virtualized
environments, because:
a) We can't share the same buffer between different virtual machines
b) Physically contiguous memory as seen by VM can be non-contiguous
in reality (and as seen by OP-TEE OS) due to second stage of
MMU translation.
c) Size of this pre-shared buffer is limited.
So, first part of this pull request adds generic register/unregister
interface to tee subsystem. The second part adds necessary features into
OP-TEE driver, so it can use not only static pre-shared buffer, but
whole RAM to communicate with OP-TEE OS.
This change is backwards compatible allowing older secure world or
user space to work with newer kernels and vice versa.
[1] https://www.globalplatform.org/specificationsdevice.asp
* tag 'tee-drv-dynamic-shm-for-v4.16' of https://git.linaro.org/people/jens.wiklander/linux-tee:
tee: shm: inline tee_shm_get_id()
tee: use reference counting for tee_context
tee: optee: enable dynamic SHM support
tee: optee: add optee-specific shared pool implementation
tee: optee: store OP-TEE capabilities in private data
tee: optee: add registered buffers handling into RPC calls
tee: optee: add registered shared parameters handling
tee: optee: add shared buffer registration functions
tee: optee: add page list manipulation functions
tee: optee: Update protocol definitions
tee: shm: add page accessor functions
tee: shm: add accessors for buffer size and page offset
tee: add register user memory
tee: flexible shared memory pool creation
bad19e0d04