Re: Qemu and ARM secure state.

[Jean-Christophe DUBOIS <jcd@tribudubois.net>]

Le 08/11/2021 à 15:14, Alex Bennée a écrit :
> Jean-Christophe DUBOIS <jcd@tribudubois.net> writes:
>
>> One small question/remark:
>>
>> According to the the "Arm Power State Coordinate Interface" (DEN0022D.b) document (chapter 5) PSCI calls can only be issued by
>> "normal world" (EL1 or EL2). Therefore, should we be adding a test for the current secure state in the arm_is_psci_call() function? This
>> would prevent calling the built-in Qemu PSCI function if SMC is issued
>> from secure state.
> All that should be handled in:
>
>    void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
>
> which should cause things to be trapped if the CPU is in an invalid
> state to execute the SMC instruction. If the exception is a valid SMC we
> end up in arm_cpu_do_interrupt where we may divert to
> arm_handle_psci_call.

The problem I have is that is seems that once the "psci-conduit" is set 
to SMC, all SMC exception would be handled only by the diverted  
arm_handle_psci_call().

It seems there is no way to handle SMC exception in my software once 
"psci-conduit" is set to SMC on a platform.

It used to be that only some PSCI services were diverted and other SMC 
services were handled by the EL3 software if any (and this split was 
actually also a bit awkward).

>