quoted

 		u64 *ptr;
 
-		ptr = per_cpu_ptr(&arm64_ssbd_callback_required, cpu);
+		ptr = per_cpu_ptr_nvhe(arm64_ssbd_callback_required, cpu);
 		err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP);
 		if (err)
 			return err;
+
+		/* Copy value from kernel to hyp. */
+		*ptr = per_cpu(arm64_ssbd_callback_required, cpu);

Hmm. Is this correct for late arriving CPUs, where we don't know whether
a callback is required at the point we do the copy?

That sounds fiddly to resolve, but this _might_ all be moot because I'm
about to post a series that allows us to remove the hyp mapping of this
variable entirely. So leave this for now, but maybe stick a comment in
that it doesn't work for late cpus.

Ah, good point. I'll move the value copy at the end of cpu_init_hyp_mode().
It must be known at that point. And if your series gets rid of this completely,
even better.

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