KEYS: trusted: tee: Refactor register SHM usage

The OP-TEE driver using the old SMC based ABI permits overlapping shared
buffers, but with the new FF-A based ABI each physical page may only
be registered once.

As the key and blob buffer are allocated adjancently, there is no need
for redundant register shared memory invocation. Also, it is incompatibile
with FF-A based ABI limitation. So refactor register shared memory
implementation to use only single invocation to register both key and blob
buffers.

[jarkko: Added cc to stable.]
Cc: stable@vger.kernel.org # v5.16+
Fixes: 4615e5a34b95 ("optee: add FF-A support")
Reported-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

KEYS: trusted: tee: Make registered shm dependency explicit

TEE trusted keys support depends on registered shared memory support
since the key buffers are needed to be registered with OP-TEE. So make
that dependency explicit to not register trusted keys support if
underlying implementation doesn't support registered shared memory.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

KEYS: trusted: tee: use tee_shm_register_kernel_buf()

Uses the new simplified tee_shm_register_kernel_buf() function instead
of the old tee_shm_alloc() function which required specific
TEE_SHM-flags

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

KEYS: trusted: Introduce TEE based Trusted Keys

Add support for TEE based trusted keys where TEE provides the functionality
to seal and unseal trusted keys using hardware unique key.

Refer to Documentation/staging/tee.rst for detailed information about TEE.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>