On 27.11.2024 13:50, Oleksii Kurochko wrote:
> Introduce the destroy_xen_mappings() function, which removes page
> mappings in Xen's page tables between a start address s and an end
> address e.
> The function ensures that both s and e are page-aligned
> and verifies that the start address is less than or equal to the end
> address before calling pt_update() to invalidate the mappings.
> The pt_update() function is called with INVALID_MFN and PTE_VALID=0
> in the flags, which tell pt_update() to remove mapping. No additional
> ASSERT() is required to check these arguments, as they are hardcoded in
> the call to pt_update() within destroy_xen_mappings().
>
> Signed-off-by: Oleksii Kurochko <oleksii.kuroc...@gmail.com>
Acked-by: Jan Beulich <jbeul...@suse.com>
However, ...
> --- a/xen/arch/riscv/pt.c
> +++ b/xen/arch/riscv/pt.c
> @@ -421,6 +421,14 @@ int map_pages_to_xen(unsigned long virt,
> return pt_update(virt, mfn, nr_mfns, flags);
> }
>
> +int destroy_xen_mappings(unsigned long s, unsigned long e)
> +{
> + ASSERT(IS_ALIGNED(s, PAGE_SIZE));
> + ASSERT(IS_ALIGNED(e, PAGE_SIZE));
> + ASSERT(s <= e);
> + return pt_update(s, INVALID_MFN, PFN_DOWN(e - s), 0);
> +}
... I'm unconvinced the constraints need to be this strict. You could,
for example, very well just avoiding to call pt_update() when s > e
(or really when s >= e). Thoughts?
Jan
