https://review.trustedfirmware.org/c/hafnium/hafnium/+/8243

I haven't looked at in much detail but I think the shareability attributes would need to be exposed by the mm module, and then converted by ffa_memory_permissions_to_mode.

SMMUv3.2 supports secure Stage-2 translations and that's the feature we intend to enable as a first step.
The IP also supports "nested translations" aka S-EL1 SMMU paravirtualization although we're not looking at this option immediately.

Thanks for your reply, so there is Stage-2 SMMU support, right? And i think we can support passthrough io support in Secure-EL1 with Stage-2 SMMU

We're considering the SMMUv3.2 support which covers the Secure Stage-2 mappings (https://developer.arm.com/documentation/ihi0070/latest).
This is still in initial investigation phases, but we hope to share design details and early patches by end of Q4'20.

@odeprez / Arm might be able to comment on this.

what about SMMUV3.x ?

Pursuing Jose's early work through Google's gerrit interface.
We'll provide more design details in the shared SPM doc.

This should also include some interface for multiplexing secondary VM requests, first a documented convention and then a reference implementation.