drm/virtio: make resource id workaround runtime switchable.

Also update the comment with a reference to the virglrenderer fix.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190822102614.18164-1-kraxel@redhat.com

diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index b2da313..e98aaa0 100644 (file)
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -27,34 +27,38 @@
 
 #include "virtgpu_drv.h"
 
+static int virtio_gpu_virglrenderer_workaround = 1;
+module_param_named(virglhack, virtio_gpu_virglrenderer_workaround, int, 0400);
+
 static int virtio_gpu_resource_id_get(struct virtio_gpu_device *vgdev,
                                       uint32_t *resid)
 {
-#if 0
-       int handle = ida_alloc(&vgdev->resource_ida, GFP_KERNEL);
-
-       if (handle < 0)
-               return handle;
-#else
-       static int handle;
-
-       /*
-        * FIXME: dirty hack to avoid re-using IDs, virglrenderer
-        * can't deal with that.  Needs fixing in virglrenderer, also
-        * should figure a better way to handle that in the guest.
-        */
-       handle++;
-#endif
-
-       *resid = handle + 1;
+       if (virtio_gpu_virglrenderer_workaround) {
+               /*
+                * Hack to avoid re-using resource IDs.
+                *
+                * virglrenderer versions up to (and including) 0.7.0
+                * can't deal with that.  virglrenderer commit
+                * "f91a9dd35715 Fix unlinking resources from hash
+                * table." (Feb 2019) fixes the bug.
+                */
+               static int handle;
+               handle++;
+               *resid = handle + 1;
+       } else {
+               int handle = ida_alloc(&vgdev->resource_ida, GFP_KERNEL);
+               if (handle < 0)
+                       return handle;
+               *resid = handle + 1;
+       }
        return 0;
 }
 
 static void virtio_gpu_resource_id_put(struct virtio_gpu_device *vgdev, uint32_t id)
 {
-#if 0
-       ida_free(&vgdev->resource_ida, id - 1);
-#endif
+       if (!virtio_gpu_virglrenderer_workaround) {
+               ida_free(&vgdev->resource_ida, id - 1);
+       }
 }
 
 static void virtio_gpu_ttm_bo_destroy(struct ttm_buffer_object *tbo)