In order to prepare xenstored supporting migration stream versions
other than 1, add a parameter to the live update command allowing to
specify the version of the migration stream.

This will allow going back from xenstored using version 2 per default
to a xenstored only accepting version 1.

For now only version 1 is supported.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 tools/xenstored/control.c           |  6 ++---
 tools/xenstored/lu.c                | 21 ++++++++++-----
 tools/xenstored/lu.h                |  1 +
 tools/xs-clients/xenstore_control.c | 41 ++++++++++++++++++++++-------
 4 files changed, 50 insertions(+), 19 deletions(-)

diff --git a/tools/xenstored/control.c b/tools/xenstored/control.c
index 9561289179..953c01b735 100644
--- a/tools/xenstored/control.c
+++ b/tools/xenstored/control.c
@@ -289,7 +289,7 @@ static struct cmd_s cmds[] = {
 	 *    Mini-OS: -b <binary-size>
 	 *             -d <size> <data-bytes> (multiple of those)
 	 * 2. New command-line (optional): -c <cmdline>
-	 * 3. Start of update: -s [-F] [-t <timeout>]
+	 * 3. Start of update: -s [-F] [-t <timeout>] [-v <version>]
 	 * Any sub-operation needs to respond with the string "OK" in case
 	 * of success, any other response indicates failure.
 	 * A started live-update sequence can be aborted via "-a" (not
@@ -297,8 +297,8 @@ static struct cmd_s cmds[] = {
 	 * sub-operation).
 	 */
 	{ "live-update", do_control_lu,
-		"[-c <cmdline>] [-F] [-t <timeout>] <file>\n"
-		"    Default timeout is 60 seconds.", 5 },
+		"[-c <cmdline>] [-F] [-t <timeout>] [-v <version>] <file>\n"
+		"    Default timeout is 60 seconds, default version is 1.", 7 },
 #endif
 	{ "logfile", do_control_logfile, "<file>" },
 	{ "memreport", do_control_memreport, "[<file>]" },
diff --git a/tools/xenstored/lu.c b/tools/xenstored/lu.c
index 4fccbbc195..330820a8a2 100644
--- a/tools/xenstored/lu.c
+++ b/tools/xenstored/lu.c
@@ -283,7 +283,7 @@ static const char *lu_dump_state(const void *ctx, struct connection *conn)
 		return "Dump state open error";
 
 	memcpy(pre.ident, XS_STATE_IDENT, sizeof(pre.ident));
-	pre.version = htobe32(XS_STATE_VERSION);
+	pre.version = htobe32(lu_status->version);
 	pre.flags = XS_STATE_FLAGS;
 	if (fwrite(&pre, sizeof(pre), 1, fp) != 1) {
 		ret = "Dump write error";
@@ -412,13 +412,16 @@ static bool do_lu_start(struct delayed_request *req)
 }
 
 static const char *lu_start(const void *ctx, struct connection *conn,
-			    bool force, unsigned int to)
+			    bool force, unsigned int to, unsigned int vers)
 {
 	syslog(LOG_INFO, "live-update: start, force=%d, to=%u\n", force, to);
 
 	if (!lu_status || lu_status->conn != conn)
 		return "Not in live-update session.";
 
+	if (!vers || vers > XS_STATE_VERSION)
+		return "Migration stream version not supported.";
+
 #ifdef __MINIOS__
 	if (lu_status->kernel_size != lu_status->kernel_off)
 		return "Kernel not complete.";
@@ -426,6 +429,7 @@ static const char *lu_start(const void *ctx, struct connection *conn,
 
 	lu_status->force = force;
 	lu_status->timeout = to;
+	lu_status->version = vers;
 	lu_status->started_at = time(NULL);
 	lu_status->in = conn->in;
 
@@ -441,6 +445,7 @@ int do_control_lu(const void *ctx, struct connection *conn, const char **vec,
 	unsigned int i;
 	bool force = false;
 	unsigned int to = 0;
+	unsigned int vers = XS_STATE_VERSION;
 
 	if (num < 1)
 		return EINVAL;
@@ -457,15 +462,19 @@ int do_control_lu(const void *ctx, struct connection *conn, const char **vec,
 			return EINVAL;
 	} else if (!strcmp(vec[0], "-s")) {
 		for (i = 1; i < num; i++) {
-			if (!strcmp(vec[i], "-F"))
+			if (!strcmp(vec[i], "-F")) {
 				force = true;
-			else if (!strcmp(vec[i], "-t") && i < num - 1) {
+			} else if (!strcmp(vec[i], "-t") && i < num - 1) {
 				i++;
 				to = atoi(vec[i]);
-			} else
+			} else if (!strcmp(vec[i], "-v") && i < num - 1) {
+				i++;
+				vers = atoi(vec[i]);
+			} else {
 				return EINVAL;
+			}
 		}
-		ret = lu_start(ctx, conn, force, to);
+		ret = lu_start(ctx, conn, force, to, vers);
 		if (!ret)
 			return errno;
 	} else {
diff --git a/tools/xenstored/lu.h b/tools/xenstored/lu.h
index dacc9b6e42..512b8a6db2 100644
--- a/tools/xenstored/lu.h
+++ b/tools/xenstored/lu.h
@@ -26,6 +26,7 @@ struct live_update {
 	/* Start parameters. */
 	bool force;
 	unsigned int timeout;
+	unsigned int version;
 	time_t started_at;
 };
 
diff --git a/tools/xs-clients/xenstore_control.c b/tools/xs-clients/xenstore_control.c
index 548363ee70..4b523931ce 100644
--- a/tools/xs-clients/xenstore_control.c
+++ b/tools/xs-clients/xenstore_control.c
@@ -26,7 +26,8 @@ static int add_to_buf(char **buf, const char *val, int len)
     return len + vallen;
 }
 
-static int live_update_start(struct xs_handle *xsh, bool force, unsigned int to)
+static int live_update_start(struct xs_handle *xsh, bool force, unsigned int to,
+                             unsigned int vers)
 {
     int len = 0;
     char *buf = NULL, *ret;
@@ -40,6 +41,15 @@ static int live_update_start(struct xs_handle *xsh, bool force, unsigned int to)
     free(ret);
     if (force)
         len = add_to_buf(&buf, "-F", len);
+    if (vers) {
+        if (asprintf(&ret, "%u", vers) < 0) {
+            free(buf);
+            return 1;
+        }
+        len = add_to_buf(&buf, "-v", len);
+        len = add_to_buf(&buf, ret, len);
+        free(ret);
+    }
     if (len < 0)
         return 1;
 
@@ -197,7 +207,8 @@ static int send_kernel_blob(struct xs_handle *xsh, const char *binary)
  * 3. start update (includes flags)
  */
 static int live_update_stubdom(struct xs_handle *xsh, const char *binary,
-                               const char *cmdline, bool force, unsigned int to)
+                               const char *cmdline, bool force, unsigned int to,
+                               unsigned int vers)
 {
     int rc;
 
@@ -211,7 +222,7 @@ static int live_update_stubdom(struct xs_handle *xsh, const char *binary,
             goto abort;
     }
 
-    rc = live_update_start(xsh, force, to);
+    rc = live_update_start(xsh, force, to, vers);
     if (rc)
         goto abort;
 
@@ -231,7 +242,8 @@ static int live_update_stubdom(struct xs_handle *xsh, const char *binary,
  * 3. start update (includes flags)
  */
 static int live_update_daemon(struct xs_handle *xsh, const char *binary,
-                              const char *cmdline, bool force, unsigned int to)
+                              const char *cmdline, bool force, unsigned int to,
+                              unsigned int vers)
 {
     int len = 0, rc;
     char *buf = NULL, *ret;
@@ -256,7 +268,7 @@ static int live_update_daemon(struct xs_handle *xsh, const char *binary,
             goto abort;
     }
 
-    rc = live_update_start(xsh, force, to);
+    rc = live_update_start(xsh, force, to, vers);
     if (rc)
         goto abort;
 
@@ -270,7 +282,7 @@ static int live_update_daemon(struct xs_handle *xsh, const char *binary,
 static int live_update(struct xs_handle *xsh, int argc, char **argv)
 {
     int rc = 0;
-    unsigned int i, to = 60;
+    unsigned int i, to = 60, vers = 0;
     char *binary = NULL, *cmdline = NULL, *val;
     bool force = false;
 
@@ -291,10 +303,19 @@ static int live_update(struct xs_handle *xsh, int argc, char **argv)
                 goto out;
             }
             to = atoi(argv[i]);
-        } else if (!strcmp(argv[i], "-F"))
+        } else if (!strcmp(argv[i], "-F")) {
             force = true;
-        else
+        } else if (!strcmp(argv[i], "-v")) {
+            i++;
+            if (i == argc) {
+                fprintf(stderr, "Missing version value\n");
+                rc = 2;
+                goto out;
+            }
+            vers = atoi(argv[i]);
+        } else {
             binary = argv[i];
+        }
     }
 
     if (!binary) {
@@ -305,9 +326,9 @@ static int live_update(struct xs_handle *xsh, int argc, char **argv)
 
     val = xs_read(xsh, XBT_NULL, "/tool/xenstored/domid", &i);
     if (val)
-        rc = live_update_stubdom(xsh, binary, cmdline, force, to);
+        rc = live_update_stubdom(xsh, binary, cmdline, force, to, vers);
     else
-        rc = live_update_daemon(xsh, binary, cmdline, force, to);
+        rc = live_update_daemon(xsh, binary, cmdline, force, to, vers);
 
     free(val);
 
-- 
2.43.0

On 2025-07-22 10:06, Juergen Gross wrote:
> In order to prepare xenstored supporting migration stream versions
> other than 1, add a parameter to the live update command allowing to
> specify the version of the migration stream.
> 
> This will allow going back from xenstored using version 2 per default
> to a xenstored only accepting version 1.
> 
> For now only version 1 is supported.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>