[virtio-dev][RFC PATCH v1 2/2] virtio-gpu: add the ability to export resources

[David Stevens <stevensd@chromium.org>]

Signed-off-by: David Stevens <stevensd@chromium.org>
---
 virtio-gpu.tex | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/virtio-gpu.tex b/virtio-gpu.tex
index af4ca61..522f478 100644
--- a/virtio-gpu.tex
+++ b/virtio-gpu.tex
@@ -186,12 +186,16 @@ \subsubsection{Device Operation: Request
header}\label{sec:Device Types / GPU De
         VIRTIO_GPU_CMD_UPDATE_CURSOR = 0x0300,
         VIRTIO_GPU_CMD_MOVE_CURSOR,

+        /* misc commands */
+        VIRTIO_GPU_CMD_EXPORT_RESOURCE = 0x0400,
+
         /* success responses */
         VIRTIO_GPU_RESP_OK_NODATA = 0x1100,
         VIRTIO_GPU_RESP_OK_DISPLAY_INFO,
         VIRTIO_GPU_RESP_OK_CAPSET_INFO,
         VIRTIO_GPU_RESP_OK_CAPSET,
         VIRTIO_GPU_RESP_OK_EDID,
+        VIRTIO_GPU_RESP_OK_EXPORT_RESOURCE,

         /* error responses */
         VIRTIO_GPU_RESP_ERR_UNSPEC = 0x1200,
@@ -454,6 +458,31 @@ \subsubsection{Device Operation:
controlq}\label{sec:Device Types / GPU Device /
 This detaches any backing pages from a resource, to be used in case of
 guest swapping or object destruction.

+\item[VIRTIO_GPU_CMD_EXPORT_RESOURCE] Exports a resource for use by other
+  virtio devices. Request data is \field{struct
+    virtio_gpu_export_resource}.  Response type is
+  VIRTIO_GPU_RESP_OK_EXPORT_RESOURCE, response data is \field{struct
+    virtio_gpu_resp_export_resource}.
+
+\begin{lstlisting}
+struct virtio_gpu_export_resource {
+        struct virtio_gpu_ctrl_hdr hdr;
+        le32 resource_id;
+        le32 padding;
+};
+
+struct virtio_gpu_resp_export_resource {
+        struct virtio_gpu_ctrl_hdr hdr;
+        le64 uuid_low;
+        le64 uuid_high;
+};
+\end{lstlisting}
+
+The response contains a uuid which identifies the host private resource to
+other virtio devices. Note that if the resource has an attached backing,
+modifications made to an exported resource by other devices are not visible
+in the attached backing until they are transferred into the backing.
+
 \end{description}

 \subsubsection{Device Operation: cursorq}\label{sec:Device Types /
GPU Device / Device Operation / Device Operation: cursorq}
-- 
2.24.1.735.g03f4e72817-goog