vtest: Add versioning mechanism to protocol

This commit negotiates a common protocol version with the clients,
allowing for backwards compatibility on both sides.

v2: - Negotiate the version in a new command, so the client can probe
      for its existence and stay compatible with older servers. (Dave
      Airlie)

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

@@ -43,6 +43,7 @@ int vtest_renderer_create_fence(void);
 int vtest_poll(void);
 
 int vtest_ping_protocol_version(void);
+int vtest_protocol_version(void);
 
 void vtest_destroy_renderer(void);
 #endif

vtest/vtest_protocol.h

@@ -25,6 +25,7 @@
 #define VTEST_PROTOCOL
 
 #define VTEST_DEFAULT_SOCKET_NAME "/tmp/.virgl_test"
+#define VTEST_PROTOCOL_VERSION 1
 
 /* 32-bit length field */
 /* 32-bit cmd field */
@@ -56,6 +57,8 @@
 
 #define VCMD_PING_PROTOCOL_VERSION 10
 
+#define VCMD_PROTOCOL_VERSION 11
+
 #define VCMD_RES_CREATE_SIZE 10
 #define VCMD_RES_CREATE_RES_HANDLE 0
 #define VCMD_RES_CREATE_TARGET 1
@@ -92,4 +95,7 @@
 
 #define VCMD_PING_PROTOCOL_VERSION_SIZE 0
 
+#define VCMD_PROTOCOL_VERSION_SIZE 1
+#define VCMD_PROTOCOL_VERSION_VERSION 0
+
 #endif

vtest/vtest_renderer.c

@@ -35,6 +35,7 @@
 #include "vtest_protocol.h"
 #include "util.h"
 #include "util/u_debug.h"
+#include "util/u_math.h"
 
 static int ctx_id = 1;
 static int fence_id = 1;
@@ -53,6 +54,7 @@ struct virgl_renderer_callbacks vtest_cbs = {
 struct vtest_renderer {
   int in_fd;
   int out_fd;
+  unsigned protocol_version;
 };
 
 struct vtest_renderer renderer;
@@ -119,6 +121,9 @@ int vtest_create_renderer(int in_fd, int out_fd, uint32_t length)
     renderer.in_fd = in_fd;
     renderer.out_fd = out_fd;
 
+    /* By default we support version 0 unless VCMD_PROTOCOL_VERSION is sent */
+    renderer.protocol_version = 0;
+
     if (getenv("VTEST_USE_GLX"))
        ctx = VIRGL_RENDERER_USE_GLX;
 
@@ -175,6 +180,35 @@ int vtest_ping_protocol_version(void)
     return 0;
 }
 
+int vtest_protocol_version(void)
+{
+    uint32_t hdr_buf[VTEST_HDR_SIZE];
+    uint32_t version_buf[VCMD_PROTOCOL_VERSION_SIZE];
+    int ret;
+
+    ret = vtest_block_read(renderer.in_fd, &version_buf, sizeof(version_buf));
+    if (ret != sizeof(version_buf))
+        return -1;
+
+    renderer.protocol_version = MIN2(version_buf[VCMD_PROTOCOL_VERSION_VERSION],
+                                     VTEST_PROTOCOL_VERSION);
+
+    hdr_buf[VTEST_CMD_LEN] = VCMD_PROTOCOL_VERSION_SIZE;
+    hdr_buf[VTEST_CMD_ID] = VCMD_PROTOCOL_VERSION;
+
+    version_buf[VCMD_PROTOCOL_VERSION_VERSION] = renderer.protocol_version;
+
+    ret = vtest_block_write(renderer.out_fd, hdr_buf, sizeof(hdr_buf));
+    if (ret < 0)
+      return ret;
+
+    ret = vtest_block_write(renderer.out_fd, version_buf, sizeof(version_buf));
+    if (ret < 0)
+      return ret;
+
+    return 0;
+}
+
 void vtest_destroy_renderer(void)
 {
   virgl_renderer_context_destroy(ctx_id);

vtest/vtest_server.c

@@ -135,6 +135,9 @@ again:
       case VCMD_PING_PROTOCOL_VERSION:
 	ret = vtest_ping_protocol_version();
 	break;
+      case VCMD_PROTOCOL_VERSION:
+	ret = vtest_protocol_version();
+	break;
       default:
 	break;
       }