On Thu, Aug 22, 2024 at 02:15:24AM +0100, Mark Brown wrote:
> @@ -512,10 +538,16 @@ static void gcs_thread_switch(struct task_struct *next)
>               gcs_set_el0_mode(next);
>  
>       /*
> -      * Ensure that GCS changes are observable by/from other PEs in
> -      * case of migration.
> +      * Ensure that GCS memory effects of the 'prev' thread are
> +      * ordered before other memory accesses with release semantics
> +      * (or preceded by a DMB) on the current PE. In addition, any
> +      * memory accesses with acquire semantics (or succeeded by a
> +      * DMB) are ordered before GCS memory effects of the 'next'
> +      * thread. This will ensure that the GCS memory effects are
> +      * visible to other PEs in case of migration.
>        */
> -     gcsb_dsync();
> +     if (task_gcs_el0_enabled(current) || task_gcs_el0_enabled(next))
> +             gcsb_dsync();
>  }

Ah, the comment turned up in this patch. It looks fine.

Reviewed-by: Catalin Marinas <catalin.mari...@arm.com>

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