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-rw-r--r--exec.c75
-rw-r--r--hw/display/exynos4210_fimd.c11
-rw-r--r--hw/display/framebuffer.c11
-rw-r--r--hw/display/g364fb.c28
-rw-r--r--hw/display/qxl.c34
-rw-r--r--hw/display/qxl.h2
-rw-r--r--hw/display/vga.c50
-rw-r--r--hw/display/virtio-gpu.c41
-rw-r--r--hw/display/vmware_vga.c21
-rw-r--r--include/exec/memory.h47
-rw-r--r--include/exec/ram_addr.h7
-rw-r--r--include/hw/virtio/virtio-gpu.h2
-rw-r--r--include/qemu/bitmap.h2
-rw-r--r--include/qemu/typedefs.h1
-rw-r--r--memory.c17
-rw-r--r--ui/console.c4
-rw-r--r--util/bitmap.c11
17 files changed, 251 insertions, 113 deletions
diff --git a/exec.c b/exec.c
index c2def9ecf2..eac6085760 100644
--- a/exec.c
+++ b/exec.c
@@ -223,6 +223,12 @@ struct CPUAddressSpace {
     MemoryListener tcg_as_listener;
 };
 
+struct DirtyBitmapSnapshot {
+    ram_addr_t start;
+    ram_addr_t end;
+    unsigned long dirty[];
+};
+
 #endif
 
 #if !defined(CONFIG_USER_ONLY)
@@ -1061,6 +1067,75 @@ bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
     return dirty;
 }
 
+DirtyBitmapSnapshot *cpu_physical_memory_snapshot_and_clear_dirty
+     (ram_addr_t start, ram_addr_t length, unsigned client)
+{
+    DirtyMemoryBlocks *blocks;
+    unsigned long align = 1UL << (TARGET_PAGE_BITS + BITS_PER_LEVEL);
+    ram_addr_t first = QEMU_ALIGN_DOWN(start, align);
+    ram_addr_t last  = QEMU_ALIGN_UP(start + length, align);
+    DirtyBitmapSnapshot *snap;
+    unsigned long page, end, dest;
+
+    snap = g_malloc0(sizeof(*snap) +
+                     ((last - first) >> (TARGET_PAGE_BITS + 3)));
+    snap->start = first;
+    snap->end   = last;
+
+    page = first >> TARGET_PAGE_BITS;
+    end  = last  >> TARGET_PAGE_BITS;
+    dest = 0;
+
+    rcu_read_lock();
+
+    blocks = atomic_rcu_read(&ram_list.dirty_memory[client]);
+
+    while (page < end) {
+        unsigned long idx = page / DIRTY_MEMORY_BLOCK_SIZE;
+        unsigned long offset = page % DIRTY_MEMORY_BLOCK_SIZE;
+        unsigned long num = MIN(end - page, DIRTY_MEMORY_BLOCK_SIZE - offset);
+
+        assert(QEMU_IS_ALIGNED(offset, (1 << BITS_PER_LEVEL)));
+        assert(QEMU_IS_ALIGNED(num,    (1 << BITS_PER_LEVEL)));
+        offset >>= BITS_PER_LEVEL;
+
+        bitmap_copy_and_clear_atomic(snap->dirty + dest,
+                                     blocks->blocks[idx] + offset,
+                                     num);
+        page += num;
+        dest += num >> BITS_PER_LEVEL;
+    }
+
+    rcu_read_unlock();
+
+    if (tcg_enabled()) {
+        tlb_reset_dirty_range_all(start, length);
+    }
+
+    return snap;
+}
+
+bool cpu_physical_memory_snapshot_get_dirty(DirtyBitmapSnapshot *snap,
+                                            ram_addr_t start,
+                                            ram_addr_t length)
+{
+    unsigned long page, end;
+
+    assert(start >= snap->start);
+    assert(start + length <= snap->end);
+
+    end = TARGET_PAGE_ALIGN(start + length - snap->start) >> TARGET_PAGE_BITS;
+    page = (start - snap->start) >> TARGET_PAGE_BITS;
+
+    while (page < end) {
+        if (test_bit(page, snap->dirty)) {
+            return true;
+        }
+        page++;
+    }
+    return false;
+}
+
 /* Called from RCU critical section */
 hwaddr memory_region_section_get_iotlb(CPUState *cpu,
                                        MemoryRegionSection *section,
diff --git a/hw/display/exynos4210_fimd.c b/hw/display/exynos4210_fimd.c
index e5be713406..fd0b2bec65 100644
--- a/hw/display/exynos4210_fimd.c
+++ b/hw/display/exynos4210_fimd.c
@@ -1263,6 +1263,7 @@ static void exynos4210_fimd_update(void *opaque)
     Exynos4210fimdState *s = (Exynos4210fimdState *)opaque;
     DisplaySurface *surface;
     Exynos4210fimdWindow *w;
+    DirtyBitmapSnapshot *snap;
     int i, line;
     hwaddr fb_line_addr, inc_size;
     int scrn_height;
@@ -1291,10 +1292,12 @@ static void exynos4210_fimd_update(void *opaque)
             memory_region_sync_dirty_bitmap(w->mem_section.mr);
             host_fb_addr = w->host_fb_addr;
             fb_line_addr = w->mem_section.offset_within_region;
+            snap = memory_region_snapshot_and_clear_dirty(w->mem_section.mr,
+                    fb_line_addr, inc_size * scrn_height, DIRTY_MEMORY_VGA);
 
             for (line = 0; line < scrn_height; line++) {
-                is_dirty = memory_region_get_dirty(w->mem_section.mr,
-                            fb_line_addr, scrn_width, DIRTY_MEMORY_VGA);
+                is_dirty = memory_region_snapshot_get_dirty(w->mem_section.mr,
+                            snap, fb_line_addr, scrn_width);
 
                 if (s->invalidate || is_dirty) {
                     if (first_line == -1) {
@@ -1309,9 +1312,7 @@ static void exynos4210_fimd_update(void *opaque)
                 fb_line_addr += inc_size;
                 is_dirty = false;
             }
-            memory_region_reset_dirty(w->mem_section.mr,
-                w->mem_section.offset_within_region,
-                w->fb_len, DIRTY_MEMORY_VGA);
+            g_free(snap);
             blend = true;
         }
     }
diff --git a/hw/display/framebuffer.c b/hw/display/framebuffer.c
index 25aa46c8c7..d7310d25f2 100644
--- a/hw/display/framebuffer.c
+++ b/hw/display/framebuffer.c
@@ -67,7 +67,7 @@ void framebuffer_update_display(
     int *first_row, /* Input and output.  */
     int *last_row /* Output only */)
 {
-    hwaddr src_len;
+    DirtyBitmapSnapshot *snap;
     uint8_t *dest;
     uint8_t *src;
     int first, last = 0;
@@ -78,7 +78,6 @@ void framebuffer_update_display(
 
     i = *first_row;
     *first_row = -1;
-    src_len = (hwaddr)src_width * rows;
 
     mem = mem_section->mr;
     if (!mem) {
@@ -102,9 +101,10 @@ void framebuffer_update_display(
     src += i * src_width;
     dest += i * dest_row_pitch;
 
+    snap = memory_region_snapshot_and_clear_dirty(mem, addr, src_width * rows,
+                                                  DIRTY_MEMORY_VGA);
     for (; i < rows; i++) {
-        dirty = memory_region_get_dirty(mem, addr, src_width,
-                                             DIRTY_MEMORY_VGA);
+        dirty = memory_region_snapshot_get_dirty(mem, snap, addr, src_width);
         if (dirty || invalidate) {
             fn(opaque, dest, src, cols, dest_col_pitch);
             if (first == -1)
@@ -115,11 +115,10 @@ void framebuffer_update_display(
         src += src_width;
         dest += dest_row_pitch;
     }
+    g_free(snap);
     if (first < 0) {
         return;
     }
-    memory_region_reset_dirty(mem, mem_section->offset_within_region, src_len,
-                              DIRTY_MEMORY_VGA);
     *first_row = first;
     *last_row = last;
 }
diff --git a/hw/display/g364fb.c b/hw/display/g364fb.c
index 8cdc205dd9..86557d14a9 100644
--- a/hw/display/g364fb.c
+++ b/hw/display/g364fb.c
@@ -64,17 +64,8 @@ typedef struct G364State {
 
 static inline int check_dirty(G364State *s, ram_addr_t page)
 {
-    return memory_region_get_dirty(&s->mem_vram, page, G364_PAGE_SIZE,
-                                   DIRTY_MEMORY_VGA);
-}
-
-static inline void reset_dirty(G364State *s,
-                               ram_addr_t page_min, ram_addr_t page_max)
-{
-    memory_region_reset_dirty(&s->mem_vram,
-                              page_min,
-                              page_max + G364_PAGE_SIZE - page_min - 1,
-                              DIRTY_MEMORY_VGA);
+    return memory_region_test_and_clear_dirty(&s->mem_vram, page, G364_PAGE_SIZE,
+                                              DIRTY_MEMORY_VGA);
 }
 
 static void g364fb_draw_graphic8(G364State *s)
@@ -83,7 +74,7 @@ static void g364fb_draw_graphic8(G364State *s)
     int i, w;
     uint8_t *vram;
     uint8_t *data_display, *dd;
-    ram_addr_t page, page_min, page_max;
+    ram_addr_t page;
     int x, y;
     int xmin, xmax;
     int ymin, ymax;
@@ -114,8 +105,6 @@ static void g364fb_draw_graphic8(G364State *s)
     }
 
     page = 0;
-    page_min = (ram_addr_t)-1;
-    page_max = 0;
 
     x = y = 0;
     xmin = s->width;
@@ -137,9 +126,6 @@ static void g364fb_draw_graphic8(G364State *s)
         if (check_dirty(s, page)) {
             if (y < ymin)
                 ymin = ymax = y;
-            if (page_min == (ram_addr_t)-1)
-                page_min = page;
-            page_max = page;
             if (x < xmin)
                 xmin = x;
             for (i = 0; i < G364_PAGE_SIZE; i++) {
@@ -196,10 +182,7 @@ static void g364fb_draw_graphic8(G364State *s)
                 ymax = y;
         } else {
             int dy;
-            if (page_min != (ram_addr_t)-1) {
-                reset_dirty(s, page_min, page_max);
-                page_min = (ram_addr_t)-1;
-                page_max = 0;
+            if (xmax || ymax) {
                 dpy_gfx_update(s->con, xmin, ymin,
                                xmax - xmin + 1, ymax - ymin + 1);
                 xmin = s->width;
@@ -219,9 +202,8 @@ static void g364fb_draw_graphic8(G364State *s)
     }
 
 done:
-    if (page_min != (ram_addr_t)-1) {
+    if (xmax || ymax) {
         dpy_gfx_update(s->con, xmin, ymin, xmax - xmin + 1, ymax - ymin + 1);
-        reset_dirty(s, page_min, page_max);
     }
 }
 
diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index 9feae78e4e..4d94cecd72 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -305,6 +305,16 @@ void qxl_spice_reset_cursor(PCIQXLDevice *qxl)
     qxl->ssd.cursor = cursor_builtin_hidden();
 }
 
+static uint32_t qxl_crc32(const uint8_t *p, unsigned len)
+{
+    /*
+     * zlib xors the seed with 0xffffffff, and xors the result
+     * again with 0xffffffff; Both are not done with linux's crc32,
+     * which we want to be compatible with, so undo that.
+     */
+    return crc32(0xffffffff, p, len) ^ 0xffffffff;
+}
+
 static ram_addr_t qxl_rom_size(void)
 {
 #define QXL_REQUIRED_SZ (sizeof(QXLRom) + sizeof(QXLModes) + sizeof(qxl_modes))
@@ -369,6 +379,18 @@ static void init_qxl_rom(PCIQXLDevice *d)
     rom->num_pages          = cpu_to_le32(num_pages);
     rom->ram_header_offset  = cpu_to_le32(d->vga.vram_size - ram_header_size);
 
+    if (d->xres && d->yres) {
+        /* needs linux kernel 4.12+ to work */
+        rom->client_monitors_config.count = 1;
+        rom->client_monitors_config.heads[0].left = 0;
+        rom->client_monitors_config.heads[0].top = 0;
+        rom->client_monitors_config.heads[0].right = cpu_to_le32(d->xres);
+        rom->client_monitors_config.heads[0].bottom = cpu_to_le32(d->yres);
+        rom->client_monitors_config_crc = qxl_crc32(
+            (const uint8_t *)&rom->client_monitors_config,
+            sizeof(rom->client_monitors_config));
+    }
+
     d->shadow_rom = *rom;
     d->rom        = rom;
     d->modes      = modes;
@@ -1011,16 +1033,6 @@ static void interface_set_client_capabilities(QXLInstance *sin,
     qxl_send_events(qxl, QXL_INTERRUPT_CLIENT);
 }
 
-static uint32_t qxl_crc32(const uint8_t *p, unsigned len)
-{
-    /*
-     * zlib xors the seed with 0xffffffff, and xors the result
-     * again with 0xffffffff; Both are not done with linux's crc32,
-     * which we want to be compatible with, so undo that.
-     */
-    return crc32(0xffffffff, p, len) ^ 0xffffffff;
-}
-
 static bool qxl_rom_monitors_config_changed(QXLRom *rom,
         VDAgentMonitorsConfig *monitors_config,
         unsigned int max_outputs)
@@ -2397,6 +2409,8 @@ static Property qxl_properties[] = {
 #if SPICE_SERVER_VERSION >= 0x000c06 /* release 0.12.6 */
         DEFINE_PROP_UINT16("max_outputs", PCIQXLDevice, max_outputs, 0),
 #endif
+        DEFINE_PROP_UINT32("xres", PCIQXLDevice, xres, 0),
+        DEFINE_PROP_UINT32("yres", PCIQXLDevice, yres, 0),
         DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/display/qxl.h b/hw/display/qxl.h
index 77e5a36dc5..f6556adb73 100644
--- a/hw/display/qxl.h
+++ b/hw/display/qxl.h
@@ -119,6 +119,8 @@ typedef struct PCIQXLDevice {
     uint32_t          vram_size_mb;
     uint32_t          vram32_size_mb;
     uint32_t          vgamem_size_mb;
+    uint32_t          xres;
+    uint32_t          yres;
 
     /* qxl_render_update state */
     int                render_update_cookie_num;
diff --git a/hw/display/vga.c b/hw/display/vga.c
index 69c3e1d674..b2516c8d21 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1434,6 +1434,14 @@ void vga_invalidate_scanlines(VGACommonState *s, int y1, int y2)
     }
 }
 
+static bool vga_scanline_invalidated(VGACommonState *s, int y)
+{
+    if (y >= VGA_MAX_HEIGHT) {
+        return false;
+    }
+    return s->invalidated_y_table[y >> 5] & (1 << (y & 0x1f));
+}
+
 void vga_sync_dirty_bitmap(VGACommonState *s)
 {
     memory_region_sync_dirty_bitmap(&s->vram);
@@ -1457,7 +1465,8 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
     DisplaySurface *surface = qemu_console_surface(s->con);
     int y1, y, update, linesize, y_start, double_scan, mask, depth;
     int width, height, shift_control, line_offset, bwidth, bits;
-    ram_addr_t page0, page1, page_min, page_max;
+    ram_addr_t page0, page1;
+    DirtyBitmapSnapshot *snap = NULL;
     int disp_width, multi_scan, multi_run;
     uint8_t *d;
     uint32_t v, addr1, addr;
@@ -1472,9 +1481,6 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
 
     full_update |= update_basic_params(s);
 
-    if (!full_update)
-        vga_sync_dirty_bitmap(s);
-
     s->get_resolution(s, &width, &height);
     disp_width = width;
 
@@ -1617,11 +1623,17 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
     addr1 = (s->start_addr * 4);
     bwidth = (width * bits + 7) / 8;
     y_start = -1;
-    page_min = -1;
-    page_max = 0;
     d = surface_data(surface);
     linesize = surface_stride(surface);
     y1 = 0;
+
+    if (!full_update) {
+        vga_sync_dirty_bitmap(s);
+        snap = memory_region_snapshot_and_clear_dirty(&s->vram, addr1,
+                                                      bwidth * height,
+                                                      DIRTY_MEMORY_VGA);
+    }
+
     for(y = 0; y < height; y++) {
         addr = addr1;
         if (!(s->cr[VGA_CRTC_MODE] & 1)) {
@@ -1636,17 +1648,17 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
         update = full_update;
         page0 = addr;
         page1 = addr + bwidth - 1;
-        update |= memory_region_get_dirty(&s->vram, page0, page1 - page0,
-                                          DIRTY_MEMORY_VGA);
-        /* explicit invalidation for the hardware cursor */
-        update |= (s->invalidated_y_table[y >> 5] >> (y & 0x1f)) & 1;
+        if (full_update) {
+            update = 1;
+        } else {
+            update = memory_region_snapshot_get_dirty(&s->vram, snap,
+                                                      page0, page1 - page0);
+        }
+        /* explicit invalidation for the hardware cursor (cirrus only) */
+        update |= vga_scanline_invalidated(s, y);
         if (update) {
             if (y_start < 0)
                 y_start = y;
-            if (page0 < page_min)
-                page_min = page0;
-            if (page1 > page_max)
-                page_max = page1;
             if (!(is_buffer_shared(surface))) {
                 vga_draw_line(s, d, s->vram_ptr + addr, width);
                 if (s->cursor_draw_line)
@@ -1679,14 +1691,8 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
         dpy_gfx_update(s->con, 0, y_start,
                        disp_width, y - y_start);
     }
-    /* reset modified pages */
-    if (page_max >= page_min) {
-        memory_region_reset_dirty(&s->vram,
-                                  page_min,
-                                  page_max - page_min,
-                                  DIRTY_MEMORY_VGA);
-    }
-    memset(s->invalidated_y_table, 0, ((height + 31) >> 5) * 4);
+    g_free(snap);
+    memset(s->invalidated_y_table, 0, sizeof(s->invalidated_y_table));
 }
 
 static void vga_draw_blank(VGACommonState *s, int full_update)
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 9b530ab5b0..e1056f34df 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -258,41 +258,22 @@ void virtio_gpu_get_display_info(VirtIOGPU *g,
 static pixman_format_code_t get_pixman_format(uint32_t virtio_gpu_format)
 {
     switch (virtio_gpu_format) {
-#ifdef HOST_WORDS_BIGENDIAN
     case VIRTIO_GPU_FORMAT_B8G8R8X8_UNORM:
-        return PIXMAN_b8g8r8x8;
+        return PIXMAN_BE_b8g8r8x8;
     case VIRTIO_GPU_FORMAT_B8G8R8A8_UNORM:
-        return PIXMAN_b8g8r8a8;
+        return PIXMAN_BE_b8g8r8a8;
     case VIRTIO_GPU_FORMAT_X8R8G8B8_UNORM:
-        return PIXMAN_x8r8g8b8;
+        return PIXMAN_BE_x8r8g8b8;
     case VIRTIO_GPU_FORMAT_A8R8G8B8_UNORM:
-        return PIXMAN_a8r8g8b8;
+        return PIXMAN_BE_a8r8g8b8;
     case VIRTIO_GPU_FORMAT_R8G8B8X8_UNORM:
-        return PIXMAN_r8g8b8x8;
+        return PIXMAN_BE_r8g8b8x8;
     case VIRTIO_GPU_FORMAT_R8G8B8A8_UNORM:
-        return PIXMAN_r8g8b8a8;
+        return PIXMAN_BE_r8g8b8a8;
     case VIRTIO_GPU_FORMAT_X8B8G8R8_UNORM:
-        return PIXMAN_x8b8g8r8;
+        return PIXMAN_BE_x8b8g8r8;
     case VIRTIO_GPU_FORMAT_A8B8G8R8_UNORM:
-        return PIXMAN_a8b8g8r8;
-#else
-    case VIRTIO_GPU_FORMAT_B8G8R8X8_UNORM:
-        return PIXMAN_x8r8g8b8;
-    case VIRTIO_GPU_FORMAT_B8G8R8A8_UNORM:
-        return PIXMAN_a8r8g8b8;
-    case VIRTIO_GPU_FORMAT_X8R8G8B8_UNORM:
-        return PIXMAN_b8g8r8x8;
-    case VIRTIO_GPU_FORMAT_A8R8G8B8_UNORM:
-        return PIXMAN_b8g8r8a8;
-    case VIRTIO_GPU_FORMAT_R8G8B8X8_UNORM:
-        return PIXMAN_x8b8g8r8;
-    case VIRTIO_GPU_FORMAT_R8G8B8A8_UNORM:
-        return PIXMAN_a8b8g8r8;
-    case VIRTIO_GPU_FORMAT_X8B8G8R8_UNORM:
-        return PIXMAN_r8g8b8x8;
-    case VIRTIO_GPU_FORMAT_A8B8G8R8_UNORM:
-        return PIXMAN_r8g8b8a8;
-#endif
+        return PIXMAN_BE_a8b8g8r8;
     default:
         return 0;
     }
@@ -1170,8 +1151,8 @@ static void virtio_gpu_device_realize(DeviceState *qdev, Error **errp)
     virtio_init(VIRTIO_DEVICE(g), "virtio-gpu", VIRTIO_ID_GPU,
                 g->config_size);
 
-    g->req_state[0].width = 1024;
-    g->req_state[0].height = 768;
+    g->req_state[0].width = g->conf.xres;
+    g->req_state[0].height = g->conf.yres;
 
     if (virtio_gpu_virgl_enabled(g->conf)) {
         /* use larger control queue in 3d mode */
@@ -1291,6 +1272,8 @@ static Property virtio_gpu_properties[] = {
     DEFINE_PROP_BIT("stats", VirtIOGPU, conf.flags,
                     VIRTIO_GPU_FLAG_STATS_ENABLED, false),
 #endif
+    DEFINE_PROP_UINT32("xres", VirtIOGPU, conf.xres, 1024),
+    DEFINE_PROP_UINT32("yres", VirtIOGPU, conf.yres, 768),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/display/vmware_vga.c b/hw/display/vmware_vga.c
index 6599cf078d..ec5f27d67e 100644
--- a/hw/display/vmware_vga.c
+++ b/hw/display/vmware_vga.c
@@ -1118,9 +1118,9 @@ static void vmsvga_update_display(void *opaque)
 {
     struct vmsvga_state_s *s = opaque;
     DisplaySurface *surface;
-    bool dirty = false;
 
-    if (!s->enable) {
+    if (!s->enable || !s->config) {
+        /* in standard vga mode */
         s->vga.hw_ops->gfx_update(&s->vga);
         return;
     }
@@ -1131,26 +1131,11 @@ static void vmsvga_update_display(void *opaque)
     vmsvga_fifo_run(s);
     vmsvga_update_rect_flush(s);
 
-    /*
-     * Is it more efficient to look at vram VGA-dirty bits or wait
-     * for the driver to issue SVGA_CMD_UPDATE?
-     */
-    if (memory_region_is_logging(&s->vga.vram, DIRTY_MEMORY_VGA)) {
-        vga_sync_dirty_bitmap(&s->vga);
-        dirty = memory_region_get_dirty(&s->vga.vram, 0,
-            surface_stride(surface) * surface_height(surface),
-            DIRTY_MEMORY_VGA);
-    }
-    if (s->invalidated || dirty) {
+    if (s->invalidated) {
         s->invalidated = 0;
         dpy_gfx_update(s->vga.con, 0, 0,
                    surface_width(surface), surface_height(surface));
     }
-    if (dirty) {
-        memory_region_reset_dirty(&s->vga.vram, 0,
-            surface_stride(surface) * surface_height(surface),
-            DIRTY_MEMORY_VGA);
-    }
 }
 
 static void vmsvga_reset(DeviceState *dev)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index c4fc94d504..99e0f54d86 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -918,6 +918,53 @@ void memory_region_set_dirty(MemoryRegion *mr, hwaddr addr,
  */
 bool memory_region_test_and_clear_dirty(MemoryRegion *mr, hwaddr addr,
                                         hwaddr size, unsigned client);
+
+/**
+ * memory_region_snapshot_and_clear_dirty: Get a snapshot of the dirty
+ *                                         bitmap and clear it.
+ *
+ * Creates a snapshot of the dirty bitmap, clears the dirty bitmap and
+ * returns the snapshot.  The snapshot can then be used to query dirty
+ * status, using memory_region_snapshot_get_dirty.  Unlike
+ * memory_region_test_and_clear_dirty this allows to query the same
+ * page multiple times, which is especially useful for display updates
+ * where the scanlines often are not page aligned.
+ *
+ * The dirty bitmap region which gets copyed into the snapshot (and
+ * cleared afterwards) can be larger than requested.  The boundaries
+ * are rounded up/down so complete bitmap longs (covering 64 pages on
+ * 64bit hosts) can be copied over into the bitmap snapshot.  Which
+ * isn't a problem for display updates as the extra pages are outside
+ * the visible area, and in case the visible area changes a full
+ * display redraw is due anyway.  Should other use cases for this
+ * function emerge we might have to revisit this implementation
+ * detail.
+ *
+ * Use g_free to release DirtyBitmapSnapshot.
+ *
+ * @mr: the memory region being queried.
+ * @addr: the address (relative to the start of the region) being queried.
+ * @size: the size of the range being queried.
+ * @client: the user of the logging information; typically %DIRTY_MEMORY_VGA.
+ */
+DirtyBitmapSnapshot *memory_region_snapshot_and_clear_dirty(MemoryRegion *mr,
+                                                            hwaddr addr,
+                                                            hwaddr size,
+                                                            unsigned client);
+
+/**
+ * memory_region_snapshot_get_dirty: Check whether a range of bytes is dirty
+ *                                   in the specified dirty bitmap snapshot.
+ *
+ * @mr: the memory region being queried.
+ * @snap: the dirty bitmap snapshot
+ * @addr: the address (relative to the start of the region) being queried.
+ * @size: the size of the range being queried.
+ */
+bool memory_region_snapshot_get_dirty(MemoryRegion *mr,
+                                      DirtyBitmapSnapshot *snap,
+                                      hwaddr addr, hwaddr size);
+
 /**
  * memory_region_sync_dirty_bitmap: Synchronize a region's dirty bitmap with
  *                                  any external TLBs (e.g. kvm)
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index c9ddcd0880..6436a413e7 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -343,6 +343,13 @@ bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
                                               ram_addr_t length,
                                               unsigned client);
 
+DirtyBitmapSnapshot *cpu_physical_memory_snapshot_and_clear_dirty
+    (ram_addr_t start, ram_addr_t length, unsigned client);
+
+bool cpu_physical_memory_snapshot_get_dirty(DirtyBitmapSnapshot *snap,
+                                            ram_addr_t start,
+                                            ram_addr_t length);
+
 static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start,
                                                          ram_addr_t length)
 {
diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index f3a98a3261..f3ffdceca4 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -72,6 +72,8 @@ struct virtio_gpu_conf {
     uint64_t max_hostmem;
     uint32_t max_outputs;
     uint32_t flags;
+    uint32_t xres;
+    uint32_t yres;
 };
 
 struct virtio_gpu_ctrl_command {
diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
index 63ea2d0b1e..c318da12d7 100644
--- a/include/qemu/bitmap.h
+++ b/include/qemu/bitmap.h
@@ -220,6 +220,8 @@ void bitmap_set(unsigned long *map, long i, long len);
 void bitmap_set_atomic(unsigned long *map, long i, long len);
 void bitmap_clear(unsigned long *map, long start, long nr);
 bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr);
+void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src,
+                                  long nr);
 unsigned long bitmap_find_next_zero_area(unsigned long *map,
                                          unsigned long size,
                                          unsigned long start,
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index e95f28cfec..f08d327aec 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -23,6 +23,7 @@ typedef struct CPUAddressSpace CPUAddressSpace;
 typedef struct CPUState CPUState;
 typedef struct DeviceListener DeviceListener;
 typedef struct DeviceState DeviceState;
+typedef struct DirtyBitmapSnapshot DirtyBitmapSnapshot;
 typedef struct DisplayChangeListener DisplayChangeListener;
 typedef struct DisplayState DisplayState;
 typedef struct DisplaySurface DisplaySurface;
diff --git a/memory.c b/memory.c
index b782d5bc5a..b727f5ec0e 100644
--- a/memory.c
+++ b/memory.c
@@ -1748,6 +1748,23 @@ bool memory_region_test_and_clear_dirty(MemoryRegion *mr, hwaddr addr,
                 memory_region_get_ram_addr(mr) + addr, size, client);
 }
 
+DirtyBitmapSnapshot *memory_region_snapshot_and_clear_dirty(MemoryRegion *mr,
+                                                            hwaddr addr,
+                                                            hwaddr size,
+                                                            unsigned client)
+{
+    assert(mr->ram_block);
+    return cpu_physical_memory_snapshot_and_clear_dirty(
+                memory_region_get_ram_addr(mr) + addr, size, client);
+}
+
+bool memory_region_snapshot_get_dirty(MemoryRegion *mr, DirtyBitmapSnapshot *snap,
+                                      hwaddr addr, hwaddr size)
+{
+    assert(mr->ram_block);
+    return cpu_physical_memory_snapshot_get_dirty(snap,
+                memory_region_get_ram_addr(mr) + addr, size);
+}
 
 void memory_region_sync_dirty_bitmap(MemoryRegion *mr)
 {
diff --git a/ui/console.c b/ui/console.c
index 419b098c11..189eecfd29 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1410,6 +1410,8 @@ void register_displaychangelistener(DisplayChangeListener *dcl)
     static DisplaySurface *dummy;
     QemuConsole *con;
 
+    assert(!dcl->ds);
+
     if (dcl->ops->dpy_gl_ctx_create) {
         /* display has opengl support */
         assert(dcl->con);
@@ -1538,6 +1540,8 @@ void dpy_gfx_replace_surface(QemuConsole *con,
     DisplaySurface *old_surface = con->surface;
     DisplayChangeListener *dcl;
 
+    assert(old_surface != surface);
+
     con->surface = surface;
     QLIST_FOREACH(dcl, &s->listeners, next) {
         if (con != (dcl->con ? dcl->con : active_console)) {
diff --git a/util/bitmap.c b/util/bitmap.c
index c1a84ca5e3..efced9a7d8 100644
--- a/util/bitmap.c
+++ b/util/bitmap.c
@@ -287,6 +287,17 @@ bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr)
     return dirty != 0;
 }
 
+void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src,
+                                  long nr)
+{
+    while (nr > 0) {
+        *dst = atomic_xchg(src, 0);
+        dst++;
+        src++;
+        nr -= BITS_PER_LONG;
+    }
+}
+
 #define ALIGN_MASK(x,mask)      (((x)+(mask))&~(mask))
 
 /**