[PATCH v4 1/5] drm/virtio: Implement VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING cmd

[Vivek Kasireddy]

This cmd is useful to let the VMM (i.e, Qemu) know that the backing
store associated with a resource is no longer valid, so that the VMM
can perform any cleanup or unmap operations.

The fence related changes and virtio_gpu_object_detach()/
virtio_gpu_detach_object_fenced() routines are extracted from a
patch by Dmitry Osipenko <dmitry.osipe...@collabora.com>.

Cc: Gerd Hoffmann <kra...@redhat.com>
Cc: Dmitry Osipenko <dmitry.osipe...@collabora.com>
Cc: Rob Clark <robdcl...@gmail.com>
Cc: Gurchetan Singh <gurchetansi...@chromium.org>
Cc: Chia-I Wu <olva...@gmail.com>
Signed-off-by: Vivek Kasireddy <vivek.kasire...@intel.com>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h    |  5 +++++
 drivers/gpu/drm/virtio/virtgpu_object.c | 23 +++++++++++++++++++++++
 drivers/gpu/drm/virtio/virtgpu_vq.c     | 25 +++++++++++++++++++++++++
 3 files changed, 53 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h 
b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 96eb576bc1b8..6584f7984b1e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -92,6 +92,7 @@ struct virtio_gpu_object {
        uint32_t hw_res_handle;
        bool dumb;
        bool created;
+       bool detached;
        bool host3d_blob, guest_blob;
        uint32_t blob_mem, blob_flags;
 
@@ -353,6 +354,10 @@ void virtio_gpu_object_attach(struct virtio_gpu_device 
*vgdev,
                              struct virtio_gpu_object *obj,
                              struct virtio_gpu_mem_entry *ents,
                              unsigned int nents);
+void virtio_gpu_object_detach(struct virtio_gpu_device *vgdev,
+                             struct virtio_gpu_object *obj,
+                             struct virtio_gpu_fence *fence);
+int virtio_gpu_detach_object_fenced(struct virtio_gpu_object *bo);
 void virtio_gpu_cursor_ping(struct virtio_gpu_device *vgdev,
                            struct virtio_gpu_output *output);
 int virtio_gpu_cmd_get_display_info(struct virtio_gpu_device *vgdev);
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c 
b/drivers/gpu/drm/virtio/virtgpu_object.c
index c7e74cf13022..53bb02c8a135 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -97,6 +97,29 @@ static void virtio_gpu_free_object(struct drm_gem_object 
*obj)
        virtio_gpu_cleanup_object(bo);
 }
 
+int virtio_gpu_detach_object_fenced(struct virtio_gpu_object *bo)
+{
+       struct virtio_gpu_device *vgdev = bo->base.base.dev->dev_private;
+       struct virtio_gpu_fence *fence;
+
+       if (bo->detached)
+               return 0;
+
+       fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
+       if (!fence)
+               return -ENOMEM;
+
+       virtio_gpu_object_detach(vgdev, bo, fence);
+       virtio_gpu_notify(vgdev);
+
+       dma_fence_wait(&fence->f, false);
+       dma_fence_put(&fence->f);
+
+       bo->detached = true;
+
+       return 0;
+}
+
 static const struct drm_gem_object_funcs virtio_gpu_shmem_funcs = {
        .free = virtio_gpu_free_object,
        .open = virtio_gpu_gem_object_open,
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c 
b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 0d3d0d09f39b..b8b296b912a1 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -645,6 +645,23 @@ virtio_gpu_cmd_resource_attach_backing(struct 
virtio_gpu_device *vgdev,
        virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, fence);
 }
 
+static void
+virtio_gpu_cmd_resource_detach_backing(struct virtio_gpu_device *vgdev,
+                                      uint32_t resource_id,
+                                      struct virtio_gpu_fence *fence)
+{
+       struct virtio_gpu_resource_detach_backing *cmd_p;
+       struct virtio_gpu_vbuffer *vbuf;
+
+       cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p));
+       memset(cmd_p, 0, sizeof(*cmd_p));
+
+       cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING);
+       cmd_p->resource_id = cpu_to_le32(resource_id);
+
+       virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, fence);
+}
+
 static void virtio_gpu_cmd_get_display_info_cb(struct virtio_gpu_device *vgdev,
                                               struct virtio_gpu_vbuffer *vbuf)
 {
@@ -1107,6 +1124,14 @@ void virtio_gpu_object_attach(struct virtio_gpu_device 
*vgdev,
                                               ents, nents, NULL);
 }
 
+void virtio_gpu_object_detach(struct virtio_gpu_device *vgdev,
+                             struct virtio_gpu_object *obj,
+                             struct virtio_gpu_fence *fence)
+{
+       virtio_gpu_cmd_resource_detach_backing(vgdev, obj->hw_res_handle,
+                                              fence);
+}
+
 void virtio_gpu_cursor_ping(struct virtio_gpu_device *vgdev,
                            struct virtio_gpu_output *output)
 {
-- 
2.45.1