Hi Volodymyr,
On 18/12/2018 21:11, Volodymyr Babchuk wrote:
From: Volodymyr Babchuk vlad.babchuk@gmail.com
Some fast SMCCC calls to OP-TEE should be handled in a special way. Capabilities exchange should be filtered out, so only caps known to mediator are used. Also mediator disables static SHM memory capability, because it can't share OP-TEE memory with a domain. Only domain can share memory with OP-TEE, so it ensures that OP-TEE supports dynamic SHM.
Basically, static SHM is a reserved memory region which is always mapped into OP-TEE address space. It belongs to OP-TEE. Normally, NW is allowed to access there, so it can communicate with OP-TEE.
On other hand, dynamic SHM is NW's own memory, which it can share with OP-TEE. OP-TEE maps this memory dynamically, when it wants to access it.
Because mediator can't share one static SHM region with all guests, it just disables it for all.
I haven't seen an answer to my question on the previous version. For reminder:
Would it make sense to still allow the hardware domain to access static SHM?
Cheers,