Documentation: Destage TEE subsystem documentation

Add a separate documentation directory for TEE subsystem since it is a
standalone subsystem which already offers devices consumed by multiple
different subsystem drivers.

Split overall TEE subsystem documentation modularly where:
- The userspace API has been moved to Documentation/userspace-api/tee.rst.
- The driver API has been moved to Documentation/driver-api/tee.rst.
- The first module covers the overview of TEE subsystem.
- The further modules are dedicated to different TEE implementations like:
- OP-TEE
- AMD-TEE
- and so on for future TEE implementation support.

Acked-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231128072352.866859-1-sumit.garg@linaro.org

tee: optee: Add SMC for loading OP-TEE image

Adds an SMC call that will pass an OP-TEE binary image to EL3 and
instruct it to load it as the BL32 payload. This works in conjunction
with a feature added to Trusted Firmware for ARMv8 and above
architectures that supports this.

The main purpose of this change is to facilitate updating the OP-TEE
component on devices via a rootfs change rather than having to do a
firmware update. Further details are linked to in the Kconfig file.

Signed-off-by: Jeffrey Kardatzke <jkardatzke@chromium.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jeffrey Kardatzke <jkardatzke@google.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

tee: simplify shm pool handling

Replaces the shared memory pool based on two pools with a single pool.
The alloc() function pointer in struct tee_shm_pool_ops gets another
parameter, align. This makes it possible to make less than page aligned
allocations from the optional reserved shared memory pool while still
making user space allocations page aligned. With in practice unchanged
behaviour using only a single pool for bookkeeping.

The allocation algorithm in the static OP-TEE shared memory pool is
changed from best-fit to first-fit since only the latter supports an
alignment parameter. The best-fit algorithm was previously the default
choice and not a conscious one.

The optee and amdtee drivers are updated as needed to work with this
changed pool handling.

This also removes OPTEE_SHM_NUM_PRIV_PAGES which becomes obsolete with
this change as the private pages can be mixed with the payload pages.

The OP-TEE driver changes minimum alignment for argument struct from 8
bytes to 512 bytes. A typical OP-TEE private shm allocation is 224 bytes
(argument struct with 6 parameters, needed for open session). So with an
alignment of 512 well waste a bit more than 50%. Before this we had a
single page reserved for this so worst case usage compared to that would
be 3 pages instead of 1 page. However, this worst case only occurs if
there is a high pressure from multiple threads on secure world. All in
all this should scale up and down better than fixed boundaries.

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

tee: optee: Fix compilation issue with nommu

The optee driver uses specific page table types to verify if a memory
region is normal. These types are not defined in nommu systems. Trying
to compile the driver in these systems results in a build error:

linux/drivers/tee/optee/call.c: In function ‘is_normal_memory’:
linux/drivers/tee/optee/call.c:533:26: error: ‘L_PTE_MT_MASK’ undeclared
(first use in this function); did you mean ‘PREEMPT_MASK’?
return (pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEALLOC;
^~~~~~~~~~~~~
PREEMPT_MASK
linux/drivers/tee/optee/call.c:533:26: note: each undeclared identifier is
reported only once for each function it appears in
linux/drivers/tee/optee/call.c:533:44: error: ‘L_PTE_MT_WRITEALLOC’ undeclared
(first use in this function)
return (pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEALLOC;
^~~~~~~~~~~~~~~~~~~

Make the optee driver depend on MMU to fix the compilation issue.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
[jw: update commit title]
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tee: optee: making OPTEE_SHM_NUM_PRIV_PAGES configurable via Kconfig

This change adds KCONFIG option to set number of pages out of
whole shared memory to be used for OP-TEE driver private data
structures.

Signed-off-by: Sahil Malhotra <sahil.malhotra@nxp.com>
[jw: fixing trivial merge conflict]
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

tee: add OP-TEE driver

Adds a OP-TEE driver which also can be compiled as a loadable module.

* Targets ARM and ARM64
* Supports using reserved memory from OP-TEE as shared memory
* Probes OP-TEE version using SMCs
* Accepts requests on privileged and unprivileged device
* Uses OPTEE message protocol version 2 to communicate with secure world

Acked-by: Andreas Dannenberg <dannenberg@ti.com>
Tested-by: Jerome Forissier <jerome.forissier@linaro.org> (HiKey)
Tested-by: Volodymyr Babchuk <vlad.babchuk@gmail.com> (RCAR H3)
Tested-by: Scott Branden <scott.branden@broadcom.com>
Reviewed-by: Javier González <javier@javigon.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>