drm/virtio: do NOT reuse resource ids

Bisected guest kernel changes crashing qemu.  Landed at
"6c1cd97bda drm/virtio: fix resource id handling".  Looked again, and
noticed we where not only leaking *some* ids, but *all* ids.  The old
code never ever called virtio_gpu_resource_id_put().

So, commit 6c1cd97bda effectively makes the linux kernel starting
re-using IDs after releasing them, and apparently virglrenderer can't
deal with that.  Oops.

This patch puts a temporary stopgap into place for the 5.0 release.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190208140409.15280-1-kraxel@redhat.com

diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index f39a183..e7e9460 100644 (file)
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -28,10 +28,21 @@
 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;
        return 0;
@@ -39,7 +50,9 @@ static int virtio_gpu_resource_id_get(struct virtio_gpu_device *vgdev,
 
 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
 }
 
 static void virtio_gpu_ttm_bo_destroy(struct ttm_buffer_object *tbo)