Commit 34fbbc16 authored by Anthony PERARD's avatar Anthony PERARD
Browse files

xen: Avoid VLA 



Avoid using a variable length array.

We allocate the `dirty_bitmap' buffer only once when we start tracking
for dirty bits.

Signed-off-by: default avatarAnthony PERARD <anthony.perard@citrix.com>
Reviewed-by: default avatarPaul Durrant <paul.durrant@citrix.com>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190618112341.513-5-anthony.perard@citrix.com>
parent 345f42b4

hw/i386/xen/xen-hvm.c

+11 −4
Original line number Diff line number Diff line
@@ -120,6 +120,8 @@ typedef struct XenIOState { 
    DeviceListener device_listener;

    hwaddr free_phys_offset;

    const XenPhysmap *log_for_dirtybit;

    /* Buffer used by xen_sync_dirty_bitmap */

    unsigned long *dirty_bitmap;



    Notifier exit;

    Notifier suspend;
@@ -465,6 +467,8 @@ static int xen_remove_from_physmap(XenIOState *state, 
    QLIST_REMOVE(physmap, list);

    if (state->log_for_dirtybit == physmap) {

        state->log_for_dirtybit = NULL;

        g_free(state->dirty_bitmap);

        state->dirty_bitmap = NULL;

    }

    g_free(physmap);
@@ -615,7 +619,7 @@ static void xen_sync_dirty_bitmap(XenIOState *state, 
{

    hwaddr npages = size >> TARGET_PAGE_BITS;

    const int width = sizeof(unsigned long) * 8;

    unsigned long bitmap[DIV_ROUND_UP(npages, width)];

    size_t bitmap_size = DIV_ROUND_UP(npages, width);

    int rc, i, j;

    const XenPhysmap *physmap = NULL;
@@ -627,13 +631,14 @@ static void xen_sync_dirty_bitmap(XenIOState *state, 


    if (state->log_for_dirtybit == NULL) {

        state->log_for_dirtybit = physmap;

        state->dirty_bitmap = g_new(unsigned long, bitmap_size);

    } else if (state->log_for_dirtybit != physmap) {

        /* Only one range for dirty bitmap can be tracked. */

        return;

    }



    rc = xen_track_dirty_vram(xen_domid, start_addr >> TARGET_PAGE_BITS,

                              npages, bitmap);

                              npages, state->dirty_bitmap);

    if (rc < 0) {

#ifndef ENODATA

#define ENODATA  ENOENT
@@ -647,8 +652,8 @@ static void xen_sync_dirty_bitmap(XenIOState *state, 
        return;

    }



    for (i = 0; i < ARRAY_SIZE(bitmap); i++) {

        unsigned long map = bitmap[i];

    for (i = 0; i < bitmap_size; i++) {

        unsigned long map = state->dirty_bitmap[i];

        while (map != 0) {

            j = ctzl(map);

            map &= ~(1ul << j);
@@ -678,6 +683,8 @@ static void xen_log_stop(MemoryListener *listener, MemoryRegionSection *section, 


    if (old & ~new & (1 << DIRTY_MEMORY_VGA)) {

        state->log_for_dirtybit = NULL;

        g_free(state->dirty_bitmap);

        state->dirty_bitmap = NULL;

        /* Disable dirty bit tracking */

        xen_track_dirty_vram(xen_domid, 0, 0, NULL);

    }