[PATCH 5.4 115/168] drm/virtio: make resource id workaround runtime switchable.

Greg Kroah-Hartman
2020-03-10T12:54:48Z

From: Gerd Hoffmann <kraxel@redhat.com>

commit 3e93bc2a58aa241081e043ef9e6e86c42808499a upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/virtio/virtgpu_object.c | 44 +++++++++++++++++---------------
1 file changed, 24 insertions(+), 20 deletions(-)

--- 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)