On Friday 15 Apr 2022 at 21:58:50 (+0000), Oliver Upton wrote:
> +/*
> + * Used to indicate a pte for which a 'make-before-break' sequence is in
'break-before-make' presumably :-) ?
<snip>
> +static void stage2_make_pte(kvm_pte_t *ptep, kvm_pte_t new, struct kvm_pgtable_mm_ops *mm_ops)
> +{
> + /* Yikes! We really shouldn't install to an entry we don't own. */
> + WARN_ON(!stage2_pte_is_locked(*ptep));
> +
> + if (stage2_pte_is_counted(new))
> + mm_ops->get_page(ptep);
> +
> + if (kvm_pte_valid(new)) {
> + WRITE_ONCE(*ptep, new);
> + dsb(ishst);
> + } else {
> + smp_store_release(ptep, new);
> + }
> +}
I'm struggling a bit to understand this pattern. We currently use
smp_store_release() to install valid mappings, which this patch seems
to change. Is the behaviour change intentional? If so, could you please
share some details about the reasoning that applies here?
Thanks,
Quentin
