In cases where the scanout buffer is provided as a texture (e.g. Virgl)
we need to check to see if it has a linear memory layout or not. If
it doesn't have a linear layout, then blitting it onto the texture
associated with the display surface (which already has a linear layout)
seems to ensure that there is no corruption seen regardless of which
encoder or decoder is used.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Frediano Ziglio <freddy77@gmail.com>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 include/ui/spice-display.h |  3 ++
 ui/spice-display.c         | 67 +++++++++++++++++++++++++++++++++++---
 2 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/include/ui/spice-display.h b/include/ui/spice-display.h
index f4922dd74b..d087d7198a 100644
--- a/include/ui/spice-display.h
+++ b/include/ui/spice-display.h
@@ -132,6 +132,9 @@ struct SimpleSpiceDisplay {
     egl_fb guest_fb;
     egl_fb blit_fb;
     egl_fb cursor_fb;
+    bool backing_y_0_top;
+    bool blit_scanout_texture;
+    bool new_scanout_texture;
     bool have_hot;
 #endif
 };
diff --git a/ui/spice-display.c b/ui/spice-display.c
index 047d453a0b..3fa15d6981 100644
--- a/ui/spice-display.c
+++ b/ui/spice-display.c
@@ -1035,20 +1035,34 @@ static void qemu_spice_gl_scanout_texture(DisplayChangeListener *dcl,
 {
     SimpleSpiceDisplay *ssd = container_of(dcl, SimpleSpiceDisplay, dcl);
     EGLint stride = 0, fourcc = 0;
+    EGLuint64KHR modifier = 0;
     int fd = -1;
 
     assert(tex_id);
-    fd = egl_get_fd_for_texture(tex_id, &stride, &fourcc, NULL);
+
+    fd = egl_get_fd_for_texture(tex_id, &stride, &fourcc, &modifier);
     if (fd < 0) {
         fprintf(stderr, "%s: failed to get fd for texture\n", __func__);
         return;
     }
     trace_qemu_spice_gl_scanout_texture(ssd->qxl.id, w, h, fourcc);
 
-    /* note: spice server will close the fd */
-    spice_qxl_gl_scanout(&ssd->qxl, fd, backing_width, backing_height,
-                         stride, fourcc, y_0_top);
-    qemu_spice_gl_monitor_config(ssd, x, y, w, h);
+    if (remote_client && modifier != DRM_FORMAT_MOD_LINEAR) {
+        egl_fb_destroy(&ssd->guest_fb);
+        egl_fb_setup_for_tex(&ssd->guest_fb,
+                             backing_width, backing_height,
+                             tex_id, false);
+        ssd->backing_y_0_top = y_0_top;
+        ssd->blit_scanout_texture = true;
+        ssd->new_scanout_texture = true;
+        close(fd);
+    } else {
+        /* note: spice server will close the fd */
+        spice_qxl_gl_scanout(&ssd->qxl, fd, backing_width, backing_height,
+                             stride, fourcc, y_0_top);
+        qemu_spice_gl_monitor_config(ssd, x, y, w, h);
+    }
+
     ssd->have_surface = false;
     ssd->have_scanout = true;
 }
@@ -1114,6 +1128,41 @@ static void qemu_spice_gl_release_dmabuf(DisplayChangeListener *dcl,
     egl_dmabuf_release_texture(dmabuf);
 }
 
+static bool spice_gl_blit_scanout_texture(SimpleSpiceDisplay *ssd)
+{
+    EGLint stride = 0, fourcc = 0;
+    int fd;
+
+    egl_fb_destroy(&ssd->blit_fb);
+    egl_fb_setup_for_tex(&ssd->blit_fb,
+                         surface_width(ssd->ds), surface_height(ssd->ds),
+                         ssd->ds->texture, false);
+    egl_fb_blit(&ssd->blit_fb, &ssd->guest_fb, false);
+    glFlush();
+
+    if (!ssd->new_scanout_texture) {
+        return true;
+    }
+
+    fd = egl_get_fd_for_texture(ssd->ds->texture,
+                                &stride, &fourcc,
+                                NULL);
+    if (fd < 0) {
+        fprintf(stderr, "%s: failed to get fd for texture\n", __func__);
+        return false;
+    }
+
+    spice_qxl_gl_scanout(&ssd->qxl, fd,
+                         surface_width(ssd->ds),
+                         surface_height(ssd->ds),
+                         stride, fourcc, ssd->backing_y_0_top);
+    qemu_spice_gl_monitor_config(ssd, 0, 0,
+                                 surface_width(ssd->ds),
+                                 surface_height(ssd->ds));
+    ssd->new_scanout_texture = false;
+    return true;
+}
+
 static void qemu_spice_gl_update(DisplayChangeListener *dcl,
                                  uint32_t x, uint32_t y, uint32_t w, uint32_t h)
 {
@@ -1121,6 +1170,7 @@ static void qemu_spice_gl_update(DisplayChangeListener *dcl,
     EGLint stride = 0, fourcc = 0;
     bool render_cursor = false;
     bool y_0_top = false; /* FIXME */
+    bool ret;
     int fd;
     uint32_t width, height, texture;
 
@@ -1195,6 +1245,13 @@ static void qemu_spice_gl_update(DisplayChangeListener *dcl,
         glFlush();
     }
 
+    if (remote_client && ssd->blit_scanout_texture) {
+        ret = spice_gl_blit_scanout_texture(ssd);
+        if (!ret) {
+            return;
+        }
+    }
+
     trace_qemu_spice_gl_update(ssd->qxl.id, w, h, x, y);
     qemu_spice_gl_block(ssd, true);
     glFlush();
-- 
2.48.1