Hi,

If CPU power off info is already known when the PSCI SMC is received in EL3, adding a platform hook early in `psci_do_cpu_off()` [1] may save rolling back any activity. It can return PSCI_E_DENIED.

[1] https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+/refs/heads/master/lib/psci/psci_off.c#43

On Fri, Apr 21, 2023 at 1:43 PM Varun Wadekar via TF-A <tf-a@lists.trustedfirmware.org> wrote:

Hello,

 

We have a use case where we want to deny the CPU power off from a certain PE. The current lib/psci does not provide a way for a platform to do this. We have support to return an error from svc_off, but this does not cover the scenario where svc_off is NULL.

 

There are multiple ways of handling this scenario.

 

  1. Introduce a new platform function to check if CPU_OFF is allowed on the core
  2. Return an error code from the pwr_domain_off() handler and unwind the CPU_OFF request
  3. Something else.

 

Any suggestions?

 

-Varun

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