[PATCH v2 0/7] KVM: arm64: Forward FFA_NOTIFICATION* calls to TrustZone

[Will Deacon]

On Mon, Jun 15, 2026 at 07:43:55AM +0000, Sebastian Ene wrote:
> On Sun, Jun 14, 2026 at 10:29:34AM +0100, Will Deacon wrote:
> > Yes, that part now seems to be missing.
> 
> I am a bit worried to apply for all of them the check from the relayer
> (ffa_check_unused_args_sbz) because of how it's written in the spec in
> (11.2 Reserved parameter convention). To be more specific, there is no
> mention of what the relayer is expected to do here (which is what hyp
> does). It says 2 things:
> 1. the caller (in this case the host driver) is expected to zero out
> unused args
> 2. the callee (Trustzone) ignores the values in these registers.
> 
> If we enforce SBZ in the relayer but (1) doesn't comply with it, we will
> introduce a regression. I left it on purpose without enforcing
> ffa_check_unused_args_sbz for the others.

I think that's ok -- if the caller isn't passing zeroes when it should,
then it's already on borrowed (no pun intended!) time and it will need
to be fixed.

Will