virtio-gpu: add VIRTIO_GPU_F_EDID feature

The feature allows the guest request an EDID blob (describing monitor
capabilities) for a given scanout (aka virtual monitor connector).

It brings a new command message, which has just a scanout field (beside
the standard virtio-gpu header) and a response message which carries the
EDID data.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20181030063206.19528-2-kraxel@redhat.com

include/uapi/linux/virtio_gpu.h

@@ -41,6 +41,7 @@
 #include <linux/types.h>
 
 #define VIRTIO_GPU_F_VIRGL 0
+#define VIRTIO_GPU_F_EDID  1
 
 enum virtio_gpu_ctrl_type {
 	VIRTIO_GPU_UNDEFINED = 0,
@@ -56,6 +57,7 @@ enum virtio_gpu_ctrl_type {
 	VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING,
 	VIRTIO_GPU_CMD_GET_CAPSET_INFO,
 	VIRTIO_GPU_CMD_GET_CAPSET,
+	VIRTIO_GPU_CMD_GET_EDID,
 
 	/* 3d commands */
 	VIRTIO_GPU_CMD_CTX_CREATE = 0x0200,
@@ -76,6 +78,7 @@ enum virtio_gpu_ctrl_type {
 	VIRTIO_GPU_RESP_OK_DISPLAY_INFO,
 	VIRTIO_GPU_RESP_OK_CAPSET_INFO,
 	VIRTIO_GPU_RESP_OK_CAPSET,
+	VIRTIO_GPU_RESP_OK_EDID,
 
 	/* error responses */
 	VIRTIO_GPU_RESP_ERR_UNSPEC = 0x1200,
@@ -291,6 +294,21 @@ struct virtio_gpu_resp_capset {
 	__u8 capset_data[];
 };
 
+/* VIRTIO_GPU_CMD_GET_EDID */
+struct virtio_gpu_cmd_get_edid {
+	struct virtio_gpu_ctrl_hdr hdr;
+	__le32 scanout;
+	__le32 padding;
+};
+
+/* VIRTIO_GPU_RESP_OK_EDID */
+struct virtio_gpu_resp_edid {
+	struct virtio_gpu_ctrl_hdr hdr;
+	__le32 size;
+	__le32 padding;
+	__u8 edid[1024];
+};
+
 #define VIRTIO_GPU_EVENT_DISPLAY (1 << 0)
 
 struct virtio_gpu_config {