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authorGerd Hoffmann <kraxel@redhat.com>2018-05-14 12:31:17 +0200
committerGerd Hoffmann <kraxel@redhat.com>2018-05-24 10:42:13 +0200
commita89fe6c329799e47aaa1663650f076b28808e186 (patch)
treea118c2f33e4ea8152430e2f2025fb8676c3ec286
parent4f50c1673a89b07f376ce5c42d22d79a79cd466d (diff)
downloadqemu-arm-a89fe6c329799e47aaa1663650f076b28808e186.tar.gz
vga: catch depth 0
depth == 0 is used to indicate 256 color modes. Our region calculation goes wrong in that case. So detect that and just take the safe code path we already have for the wraparound case. While being at it also catch depth == 15 (where our region size calculation goes wrong too). And make the comment more verbose, explaining what is going on here. Without this windows guest install might trigger an assert due to trying to check dirty bitmap outside the snapshot region. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1575541 Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Message-id: 20180514103117.21059-1-kraxel@redhat.com
-rw-r--r--hw/display/vga.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/hw/display/vga.c b/hw/display/vga.c
index 72181330b8..a7794f6d1f 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1480,13 +1480,28 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
s->get_resolution(s, &width, &height);
disp_width = width;
+ depth = s->get_bpp(s);
region_start = (s->start_addr * 4);
region_end = region_start + (ram_addr_t)s->line_offset * height;
- region_end += width * s->get_bpp(s) / 8; /* scanline length */
+ region_end += width * depth / 8; /* scanline length */
region_end -= s->line_offset;
- if (region_end > s->vbe_size) {
- /* wraps around (can happen with cirrus vbe modes) */
+ if (region_end > s->vbe_size || depth == 0 || depth == 15) {
+ /*
+ * We land here on:
+ * - wraps around (can happen with cirrus vbe modes)
+ * - depth == 0 (256 color palette video mode)
+ * - depth == 15
+ *
+ * Take the safe and slow route:
+ * - create a dirty bitmap snapshot for all vga memory.
+ * - force shadowing (so all vga memory access goes
+ * through vga_read_*() helpers).
+ *
+ * Given this affects only vga features which are pretty much
+ * unused by modern guests there should be no performance
+ * impact.
+ */
region_start = 0;
region_end = s->vbe_size;
force_shadow = true;
@@ -1520,8 +1535,6 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
}
}
- depth = s->get_bpp(s);
-
/*
* Check whether we can share the surface with the backend
* or whether we need a shadow surface. We share native