vtest: Add ping protocol version cmd

As we don't have yet a proper way of negotiating a common protocol
version to use between clients and the server, we introduce a command
without reply arguments that allows us to figure out if the server is
new enough to handle negotiation of the protocol version.

Tested-by: Jakob Bornecrantz <jakob@collabora.com>
Reviewed-by: Jakob Bornecrantz <jakob@collabora.com>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Jakob Bornecrantz <jakob@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

vtest/vtest.h

@@ -42,6 +42,8 @@ int vtest_resource_busy_wait(void);
 int vtest_renderer_create_fence(void);
 int vtest_poll(void);
 
+int vtest_ping_protocol_version(void);
+
 void vtest_destroy_renderer(void);
 #endif
 

vtest/vtest_protocol.h

@@ -54,6 +54,8 @@
 /* 0 length cmd */
 /* resp VCMD_GET_CAPS + caps */
 
+#define VCMD_PING_PROTOCOL_VERSION 10
+
 #define VCMD_RES_CREATE_SIZE 10
 #define VCMD_RES_CREATE_RES_HANDLE 0
 #define VCMD_RES_CREATE_TARGET 1
@@ -88,4 +90,6 @@
 #define VCMD_BUSY_WAIT_HANDLE 0
 #define VCMD_BUSY_WAIT_FLAGS 1
 
+#define VCMD_PING_PROTOCOL_VERSION_SIZE 0
+
 #endif

vtest/vtest_renderer.c

@@ -162,6 +162,19 @@ end:
     return ret;
 }
 
+int vtest_ping_protocol_version(void)
+{
+    uint32_t hdr_buf[VTEST_HDR_SIZE];
+    int ret;
+
+    hdr_buf[VTEST_CMD_LEN] = VCMD_PING_PROTOCOL_VERSION_SIZE;
+    hdr_buf[VTEST_CMD_ID] = VCMD_PING_PROTOCOL_VERSION;
+    ret = vtest_block_write(renderer.out_fd, hdr_buf, sizeof(hdr_buf));
+    if (ret < 0)
+	return ret;
+    return 0;
+}
+
 void vtest_destroy_renderer(void)
 {
   virgl_renderer_context_destroy(ctx_id);

vtest/vtest_server.c

@@ -132,6 +132,9 @@ again:
       case VCMD_GET_CAPS2:
 	ret = vtest_send_caps2();
 	break;
+      case VCMD_PING_PROTOCOL_VERSION:
+	ret = vtest_ping_protocol_version();
+	break;
       default:
 	break;
       }