[RFC,1/7] drm/virtio: Implement VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING cmd

Commit Message

Vivek Kasireddy March 28, 2024, 8:32 a.m. UTC

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store associated with a resource is no longer valid, so that the VMM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.

Cc: Gerd Hoffmann <[e-mail]>
Signed-off-by: Vivek Kasireddy <[e-mail]>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h |  2 ++
 drivers/gpu/drm/virtio/virtgpu_vq.c  | 15 +++++++++++++++
 2 files changed, 17 insertions(+)

Patch

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index bb7d86a0c6a1..7347835e4fbe 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -349,6 +349,8 @@  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_cmd_resource_detach_backing(struct virtio_gpu_device *vgdev,
+			      uint32_t resource_id);
 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_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index b1a00c0c25a7..17e2e7ab231a 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -645,6 +645,21 @@  virtio_gpu_cmd_resource_attach_backing(struct virtio_gpu_device *vgdev,
 	virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, fence);
 }
 
+void virtio_gpu_cmd_resource_detach_backing(struct virtio_gpu_device *vgdev,
+					    uint32_t resource_id)
+{
+	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_ctrl_buffer(vgdev, vbuf);
+}
+
 static void virtio_gpu_cmd_get_display_info_cb(struct virtio_gpu_device *vgdev,
 					       struct virtio_gpu_vbuffer *vbuf)
 {