On 07.02.2025 14:13, Oleksii Kurochko wrote:
> --- a/xen/arch/riscv/pt.c
> +++ b/xen/arch/riscv/pt.c
> @@ -185,6 +185,57 @@ static int pt_next_level(bool alloc_tbl, pte_t **table,
> unsigned int offset)
> return XEN_TABLE_NORMAL;
> }
>
> +/*
> + * _pt_walk() performs software page table walking and returns the pte_t of
> + * a leaf node or the leaf-most not-present pte_t if no leaf node is found
> + * for further analysis.
> + * Additionally, _pt_walk() returns the level of the found pte.
That's optional, which I think wants expressing here.
> + */
> +static pte_t *_pt_walk(vaddr_t va, unsigned int *pte_level)
> +{
> + const mfn_t root = get_root_page();
> + unsigned int level;
> + pte_t *table;
> +
> + DECLARE_OFFSETS(offsets, va);
> +
> + table = map_table(root);
This mapping operation doesn't look to have a counterpart. Aiui ...
> + /*
> + * Find `table` of an entry which corresponds to `va` by iterating for
> each
> + * page level and checking if the entry points to a next page table or
> + * to a page.
> + *
> + * Two cases are possible:
> + * - ret == XEN_TABLE_SUPER_PAGE means that the entry was found;
> + * (Despite the name) XEN_TABLE_SUPER_PAGE also covers 4K mappings. If
> + * pt_next_level() is called for page table level 0, it results in the
> + * entry being a pointer to a leaf node, thereby returning
> + * XEN_TABLE_SUPER_PAGE, despite of the fact this leaf covers 4k
> mapping.
> + * - ret == XEN_TABLE_MAP_NONE means that requested `va` wasn't actually
> + * mapped.
> + */
> + for ( level = HYP_PT_ROOT_LEVEL; ; --level )
> + {
> + int ret = pt_next_level(false, &table, offsets[level]);
... the mapping may be replaced here, but a new mapping will then still
be held by this function and ...
> + if ( ret == XEN_TABLE_MAP_NONE || ret == XEN_TABLE_SUPER_PAGE )
> + break;
> +
> + ASSERT(level);
> + }
> +
> + if ( pte_level )
> + *pte_level = level;
> +
> + return table + offsets[level];
> +}
... the final one then be transferred to the caller.
> +pte_t pt_walk(vaddr_t va, unsigned int *pte_level)
> +{
> + return *_pt_walk(va, pte_level);
> +}
Hence aiui there needs to be an unmap operation here.
Jan
