Hi Dan, I am not sure if this is mentioned anywhere in any documents but I think EHF handlers should be able to preempt all execution contexts at lower ELs and lower ELs should never be able to mask such interrupts. If the behavioral expectation is set the implementation can be fixed.

Thanks Sandeep

On Thu, Sep 17, 2020 at 7:57 PM Dan Handley via TF-A tf-a@lists.trustedfirmware.org wrote:

A correction...

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-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Dan Handley via TF-A Sent: 17 September 2020 15:14

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I want to handle something similar in OP-TEED along with EHF depending on

what is the expected behavior.

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Hmm, I thought OP-TEED was more like the TSP_NS_INTR_ASYNC_PREEMPT=0 case, where NS interrupts are routed to S-EL1 while processing a yielding SMC in S- EL1? Perhaps that's a better TSPD config for you to follow?

Sorry, if EL3_EXCEPTION_HANDLING=1 then obviously NS interrupts are routed to EL3 first, but the TSPD re-enables NS interrupts before handing over to the TSP to handle yielding calls, via a call to ehf_allow_ns_preemption.

Right, that is the case for yielding SMC handling where both NS interrupts and EL3/G0 interrupts can preempt the S_EL1/S_EL2 context. But I would expect the same routing model even for 'Fast SMC' unlike what is happening in TSPD.

Dan.

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