Commit 494d1997 authored by Wei Yang's avatar Wei Yang Committed by Paolo Bonzini
Browse files

exec.c: refactor function flatview_add_to_dispatch() 



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: default avatarWei Yang <richardw.yang@linux.intel.com>
Message-Id: <20190311054252.6094-1-richardw.yang@linux.intel.com>
[Paolo: move exit before adjustment of remain.offset_within_*,
 otherwise int128_get64 fails when a region is 2^64 bytes long]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e6c165f3

exec.c

+31 −17
Original line number Diff line number Diff line
@@ -1599,35 +1599,49 @@ 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.

 */

void flatview_add_to_dispatch(FlatView *fv, MemoryRegionSection *section)

{

    MemoryRegionSection now = *section, remain = *section;

    MemoryRegionSection 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;



        MemoryRegionSection now = remain;

        now.size = int128_min(int128_make64(left), now.size);

        register_subpage(fv, &now);

    } else {

        now.size = int128_zero();

        if (int128_eq(remain.size, now.size)) {

            return;

        }

    while (int128_ne(remain.size, 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);

        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 {

    }



    /* register whole pages */

    if (int128_ge(remain.size, page_size)) {

        MemoryRegionSection now = remain;

        now.size = int128_and(now.size, int128_neg(page_size));

        register_multipage(fv, &now);

        if (int128_eq(remain.size, now.size)) {

            return;

        }

        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 last subpage */

    register_subpage(fv, &remain);

}



void qemu_flush_coalesced_mmio_buffer(void)