Avoid resetting vga dirty logging unnecessarilykvm-80rc3

cirrus bitblt reset will stop and start dirty logging even when there is no
need; this causes full redraws.

avoid by only updating memory access when exiting cpu-to-video update mode.

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
index 6164f2bd5..752904222 100644
--- a/hw/cirrus_vga.c
+++ b/hw/cirrus_vga.c
@@ -860,11 +860,17 @@ static void cirrus_bitblt_cputovideo_next(CirrusVGAState * s)
 
 static void cirrus_bitblt_reset(CirrusVGAState * s)
 {
+    int need_update;
+
     s->gr[0x31] &=
 	~(CIRRUS_BLT_START | CIRRUS_BLT_BUSY | CIRRUS_BLT_FIFOUSED);
+    need_update = s->cirrus_srcptr != &s->cirrus_bltbuf[0]
+        || s->cirrus_srcptr_end != &s->cirrus_bltbuf[0];
     s->cirrus_srcptr = &s->cirrus_bltbuf[0];
     s->cirrus_srcptr_end = &s->cirrus_bltbuf[0];
     s->cirrus_srccounter = 0;
+    if (!need_update)
+        return;
     cirrus_update_memory_access(s);
 }