On 23.03.2020 10:41, Hongyan Xia wrote:
> --- a/xen/arch/x86/pv/shim.c
> +++ b/xen/arch/x86/pv/shim.c
> @@ -169,15 +169,19 @@ static void __init replace_va_mapping(struct domain *d,
> l4_pgentry_t *l4start,
> unsigned long va, mfn_t mfn)
> {
> l4_pgentry_t *pl4e = l4start + l4_table_offset(va);
> - l3_pgentry_t *pl3e = l4e_to_l3e(*pl4e) + l3_table_offset(va);
> - l2_pgentry_t *pl2e = l3e_to_l2e(*pl3e) + l2_table_offset(va);
> - l1_pgentry_t *pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(va);
> + l3_pgentry_t *pl3e = map_l3t_from_l4e(*pl4e) + l3_table_offset(va);
> + l2_pgentry_t *pl2e = map_l2t_from_l3e(*pl3e) + l2_table_offset(va);
> + l1_pgentry_t *pl1e = map_l1t_from_l2e(*pl2e) + l1_table_offset(va);
> struct page_info *page = mfn_to_page(l1e_get_mfn(*pl1e));
>
> put_page_and_type(page);
>
> *pl1e = l1e_from_mfn(mfn, (!is_pv_32bit_domain(d) ? L1_PROT
> : COMPAT_L1_PROT));
> +
> + UNMAP_DOMAIN_PAGE(pl1e);
> + UNMAP_DOMAIN_PAGE(pl2e);
> + UNMAP_DOMAIN_PAGE(pl3e);
> }
I disagree to an approach like this: Why have three pending mappings
when one at a time will do? Map-read/write-unmap three times is what
you want here, even if this is more code churn.
Jan
