On 11/03/19 06:42, Wei Yang wrote:
> flatview_add_to_dispatch() registers page based on the condition of
> *section*, which may looks like this:
>
> |s|PPPPPPP|s|
>
> where s stands for subpage and P for page.
>
> The procedure of this function could be described as:
>
> - register first subpage
> - register page
> - register last subpage
>
> This means the procedure could be simplified into these three steps
> instead of a loop iteration.
>
> This patch refactors the function into three corresponding steps and
> adds some comment to clarify it.
>
> Signed-off-by: Wei Yang <richardw.y...@linux.intel.com>
>
> ---
> v3:
> * pass int128_make64() instead of 0 to int128_gt()
> v2:
> * removes the loop iteration as suggested by Paolo
> ---
> exec.c | 50 +++++++++++++++++++++++++++++++++-----------------
> 1 file changed, 33 insertions(+), 17 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 0959b00c06..79cd561b3b 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1598,34 +1598,50 @@ static void register_multipage(FlatView *fv,
> phys_page_set(d, start_addr >> TARGET_PAGE_BITS, num_pages,
> section_index);
> }
>
> +/*
> + * The range in *section* may look like this:
> + *
> + * |s|PPPPPPP|s|
> + *
> + * where s stands for subpage and P for page.
> + *
> + * The procedure in following function could be described as:
> + *
> + * - register first subpage
> + * - register page
> + * - register last subpage
The last paragraph is a duplicate of the comments in the function, so it
can be deleted. I did that and queued the patch.
Paolo
> + */
> void flatview_add_to_dispatch(FlatView *fv, MemoryRegionSection *section)
> {
> - MemoryRegionSection now = *section, remain = *section;
> + MemoryRegionSection now, remain = *section;
> Int128 page_size = int128_make64(TARGET_PAGE_SIZE);
>
> - if (now.offset_within_address_space & ~TARGET_PAGE_MASK) {
> - uint64_t left = TARGET_PAGE_ALIGN(now.offset_within_address_space)
> - - now.offset_within_address_space;
> + /* register first subpage */
> + if (remain.offset_within_address_space & ~TARGET_PAGE_MASK) {
> + uint64_t left = TARGET_PAGE_ALIGN(remain.offset_within_address_space)
> + - remain.offset_within_address_space;
>
> + now = remain;
> now.size = int128_min(int128_make64(left), now.size);
> + remain.size = int128_sub(remain.size, now.size);
> + remain.offset_within_address_space += int128_get64(now.size);
> + remain.offset_within_region += int128_get64(now.size);
> register_subpage(fv, &now);
> - } else {
> - now.size = int128_zero();
> }
> - while (int128_ne(remain.size, now.size)) {
> +
> + /* register page */
> + if (int128_ge(remain.size, page_size)) {
> + now = remain;
> + now.size = int128_and(now.size, int128_neg(page_size));
> remain.size = int128_sub(remain.size, now.size);
> remain.offset_within_address_space += int128_get64(now.size);
> remain.offset_within_region += int128_get64(now.size);
> - now = remain;
> - if (int128_lt(remain.size, page_size)) {
> - register_subpage(fv, &now);
> - } else if (remain.offset_within_address_space & ~TARGET_PAGE_MASK) {
> - now.size = page_size;
> - register_subpage(fv, &now);
> - } else {
> - now.size = int128_and(now.size, int128_neg(page_size));
> - register_multipage(fv, &now);
> - }
> + register_multipage(fv, &now);
> + }
> +
> + /* register last subpage */
> + if (int128_gt(remain.size, int128_make64(0))) {
> + register_subpage(fv, &remain);
> }
> }
>
>
