From c7b591dff2d72eb1571f05d7f328471954980966 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Fri, 20 Oct 2017 11:06:17 +0200
Subject: [PATCH 09/11] vga: Add mechanism to force the use of a shadow surface

RH-Author: Gerd Hoffmann <kraxel@redhat.com>
Message-id: <20171020110619.2541-10-kraxel@redhat.com>
Patchwork-id: 77409
O-Subject: [RHEL-7.5 qemu-kvm PATCH 09/11] vga: Add mechanism to force the use of a shadow surface
Bugzilla: 1501294
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This prevents surface sharing which will be necessary to
fix cirrus HW cursor support.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 5508099397c480f1c3b4f14b0e64593ebe284b26)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/display/vga.c     | 17 +++++++++++++++--
 hw/display/vga_int.h |  1 +
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/hw/display/vga.c b/hw/display/vga.c
index dda3f5f..a343a0a 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1510,6 +1510,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
     uint8_t *d;
     uint32_t v, addr1, addr;
     vga_draw_line_func *vga_draw_line;
+    bool share_surface;
 #if defined(TARGET_WORDS_BIGENDIAN)
     static const bool big_endian_fb = true;
 #else
@@ -1558,18 +1559,30 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
     }
 
     depth = s->get_bpp(s);
+
+    share_surface = (!s->force_shadow) &&
+            ( depth == 32 || (depth == 16 && !byteswap) );
     if (s->line_offset != s->last_line_offset ||
         disp_width != s->last_width ||
         height != s->last_height ||
-        s->last_depth != depth) {
-        if (depth == 32 || (depth == 16 && !byteswap)) {
+        s->last_depth != depth ||
+        share_surface != is_buffer_shared(surface)) {
+        if (share_surface) {
             surface = qemu_create_displaysurface_from(disp_width,
                     height, depth, s->line_offset,
                     s->vram_ptr + (s->start_addr * 4), byteswap);
             dpy_gfx_replace_surface(s->con, surface);
+#ifdef DEBUG_VGA
+            printf("VGA: Using shared surface for depth=%d swap=%d\n",
+                   depth, byteswap);
+#endif
         } else {
             qemu_console_resize(s->con, disp_width, height);
             surface = qemu_console_surface(s->con);
+#ifdef DEBUG_VGA
+            printf("VGA: Using shadow surface for depth=%d swap=%d\n",
+                   depth, byteswap);
+#endif
         }
         s->last_scr_width = disp_width;
         s->last_scr_height = height;
diff --git a/hw/display/vga_int.h b/hw/display/vga_int.h
index 94add2f..5b9ca87 100644
--- a/hw/display/vga_int.h
+++ b/hw/display/vga_int.h
@@ -149,6 +149,7 @@ typedef struct VGACommonState {
     uint32_t last_width, last_height; /* in chars or pixels */
     uint32_t last_scr_width, last_scr_height; /* in pixels */
     uint32_t last_depth; /* in bits */
+    bool force_shadow;
     uint8_t cursor_start, cursor_end;
     bool cursor_visible_phase;
     int64_t cursor_blink_time;
-- 
1.8.3.1