>> >> AFAIK, its due the the inherent nature of tee_shm_alloc() and >> tee_shm_register() where tee_shm_alloc() doesn't need to know whether >> its a kernel or user-space memory since it is the one that allocates >> whereas tee_shm_register() need to know that since it has to register >> pre-allocated client memory. >> >>> - Why does tee_shm_register() unconditionally use non-contiguous >>> allocations without ever taking into account whether or not >>> OPTEE_SMC_SEC_CAP_DYNAMIC_SHM was set? It sounds like that's required >>> from my reading of https://optee.readthedocs.io/en/latest/architecture/core.html#noncontiguous-shared-buffers. >> >> Yeah, but do we have platforms in OP-TEE that don't support dynamic >> shared memory? I guess it has become the sane default which is a >> mandatory requirement when it comes to OP-TEE driver in u-boot. >> >>> - Why is TEE_SHM_REGISTER implemented at the TEE driver level when it is >>> specific to OP-TEE? How to better abstract that away? >>> >> >> I would like you to go through Section "3.2.4. Shared Memory" in TEE >> Client API Specification. There are two standard ways for shared >> memory approach with TEE: >> >> 1. A Shared Memory block can either be existing Client Application >> memory (kernel driver in our case) which is subsequently registered >> with the TEE Client API (using tee_shm_register() in our case). >> >> 2. Or memory which is allocated on behalf of the Client Application >> using the TEE >> Client API (using tee_shm_alloc() in our case). >> >>> Let me know if you agree with the more minimal approach that I took for >>> these bug fix series or still feel like tee_shm_register() should be >>> fixed up so that it is usable. Thanks! >> >> From drivers perspective I think the change should be: >> >> tee_shm_alloc() >> >> to >> >> kcalloc() >> tee_shm_register() > > I've just posted "[PATCH 0/7] tee: shared memory updates", > https://lore.kernel.org/lkml/20210609102324.2222332-1-jens.wiklander@xxxxxxxxxx/ > > Where tee_shm_alloc() is replaced by among other functions > tee_shm_alloc_kernel_buf(). tee_shm_alloc_kernel_buf() takes care of the > problem with TEE_SHM_DMA_BUF. > Thanks Jens. The series looks fine. Tested too. - Allen
