drm/vmwgfx: Fix a surface reference corner-case in legacy emulation mode

If running on a gb-object capable device with a non-gb capable surface
exporter (X server) and a gb capable surface referencing client (GL driver),
the referencing client expects to find a shareable backing buffer attached to
the surface at reference time. This may not be the case if the surface has
not yet been validated. This would cause the surface reference IOCTL to
return an error.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index 82468d9029156c6588a4480a9c0ed8c0aed82736..e7af580ab977f5932629b8d45e5d5e68a52942a5 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -830,6 +830,24 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
        if (unlikely(ret != 0))
                goto out_unlock;
 
+       /*
+        * A gb-aware client referencing a shared surface will
+        * expect a backup buffer to be present.
+        */
+       if (dev_priv->has_mob && req->shareable) {
+               uint32_t backup_handle;
+
+               ret = vmw_user_dmabuf_alloc(dev_priv, tfile,
+                                           res->backup_size,
+                                           true,
+                                           &backup_handle,
+                                           &res->backup);
+               if (unlikely(ret != 0)) {
+                       vmw_resource_unreference(&res);
+                       goto out_unlock;
+               }
+       }
+
        tmp = vmw_resource_reference(&srf->res);
        ret = ttm_prime_object_init(tfile, res->backup_size, &user_srf->prime,
                                    req->shareable, VMW_RES_SURFACE,