drm/vmwgfx: Prune modes based on available VRAM size

This needs to be reviewed once we support screen objects and don't rely
on VRAM for the frame-buffer.

Also fix some integer overflow issues pointed out by Michel Daenzer.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
index 409e172..086ef04 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
@@ -144,6 +144,13 @@
 		return -EINVAL;
 	}
 
+	if (!vmw_kms_validate_mode_vram(vmw_priv,
+					info->fix.line_length,
+					var->yoffset + var->yres)) {
+		DRM_ERROR("Requested geom can not fit in framebuffer\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }