[PATCH v2] riscv/plic: assign context ID based on hartid

[Thomas Gleixner]

On Mon, Oct 27 2025 at 15:03, Troy Mitchell wrote:
> The PLIC driver for OF-based platforms currently assigns 'context_id = i'
> within the context loop. This implies an assumption that all harts are
> numbered contiguously starting from 0.
>
> In Asymmetric Multi-Processing (AMP) systems, where Linux might boot on
> a non-zero hart ID (e.g., hart4), while other harts (e.g., hart0) are
> running a different OS, this assumption is violated. This can lead to
>  different system inadvertently sharing the same
> PLIC enable_base register. Consequently, this causes configuration
> conflicts and incorrect interrupt handling.
>
> Assign the PLIC context ID based on the actual hart ID provided by the
> OF node. This ensures that each hart context maps to a unique enable
> region within the PLIC, thereby resolving conflicts in AMP setups. This
> change preserves the correct behavior on Symmetric Multi-Processing (SMP)
> and Uniprocessor (UP) systems.

Can the RISCV people please have a look at this?

Thanks,

        tglx