[HVM] Live-migration fixups after 15639:c585f993385c

Use the same xenstore area for log-dirty commands as for save/continue,
and avoid a race condition by acking the save command after the save.
Signed-off-by: Tim Deegan <Tim.Deegan@xensource.com>

3 files changed, 23 insertions, 23 deletions

diff --git a/tools/ioemu/target-i386-dm/helper2.c b/tools/ioemu/target-i386-dm/helper2.c
index 7b4dcca687..070109a6cd 100644
--- a/tools/ioemu/target-i386-dm/helper2.c
+++ b/tools/ioemu/target-i386-dm/helper2.c
@@ -632,7 +632,6 @@ int main_loop(void)
             /* Wait up to 10 msec. */
             main_loop_wait(10);
 
-        xenstore_record_dm_state("paused");
         fprintf(logfile, "device model saving state\n");
 
         /* Pull all outstanding ioreqs through the system */
@@ -644,6 +643,8 @@ int main_loop(void)
                  "/var/lib/xen/qemu-save.%d", domid);
         do_savevm(qemu_file);
 
+        xenstore_record_dm_state("paused");
+
         /* Wait to be allowed to continue */
         while (suspend_requested) {
             FD_ZERO(&fds);
diff --git a/tools/ioemu/xenstore.c b/tools/ioemu/xenstore.c
index 37c535e7b5..80ba5f40a9 100644
--- a/tools/ioemu/xenstore.c
+++ b/tools/ioemu/xenstore.c
@@ -181,7 +181,8 @@ void xenstore_parse_domain_config(int domid)
     }
 
     /* Set a watch for log-dirty requests from the migration tools */
-    if (pasprintf(&buf, "%s/logdirty/next-active", path) != -1) {
+    if (pasprintf(&buf, "/local/domain/0/device-model/%u/logdirty/next-active",
+                  domid) != -1) {
         xs_watch(xsh, buf, "logdirty");
         fprintf(logfile, "Watching %s\n", buf);
     }
@@ -224,33 +225,26 @@ void xenstore_process_logdirty_event(void)
     unsigned int len;
     int i;
 
-    fprintf(logfile, "Triggered log-dirty buffer switch\n");
-
     if (!seg) {
-        char *path, *p, *key_ascii, key_terminated[17] = {0,};
+        char *path = NULL, *key_ascii, key_terminated[17] = {0,};
         key_t key;
         int shmid;
 
         /* Find and map the shared memory segment for log-dirty bitmaps */
-        if (!(path = xs_get_domain_path(xsh, domid))) {            
-            fprintf(logfile, "Log-dirty: can't get domain path in store\n");
-            exit(1);
-        }
-        if (!(path = realloc(path, strlen(path) 
-                             + strlen("/logdirty/next-active") + 1))) {
+        if (pasprintf(&path, 
+                      "/local/domain/0/device-model/%u/logdirty/key", 
+                      domid) == -1) {
             fprintf(logfile, "Log-dirty: out of memory\n");
             exit(1);
         }
-        strcat(path, "/logdirty/");
-        p = path + strlen(path);
-        strcpy(p, "key");
         
         key_ascii = xs_read(xsh, XBT_NULL, path, &len);
-        if (!key_ascii) {
+        free(path);
+
+        if (!key_ascii) 
             /* No key yet: wait for the next watch */
-            free(path);
             return;
-        }
+
         strncpy(key_terminated, key_ascii, 16);
         free(key_ascii);
         key = (key_t) strtoull(key_terminated, NULL, 16);
@@ -282,18 +276,21 @@ void xenstore_process_logdirty_event(void)
         }
 
         /* Remember the paths for the next-active and active entries */
-        strcpy(p, "active");
-        if (!(active_path = strdup(path))) {
+        if (pasprintf(&active_path, 
+                      "/local/domain/0/device-model/%u/logdirty/active",
+                      domid) == -1) {
             fprintf(logfile, "Log-dirty: out of memory\n");
             exit(1);
         }
-        strcpy(p, "next-active");
-        if (!(next_active_path = strdup(path))) {
+        if (pasprintf(&next_active_path, 
+                      "/local/domain/0/device-model/%u/logdirty/next-active",
+                      domid) == -1) {
             fprintf(logfile, "Log-dirty: out of memory\n");
             exit(1);
         }
-        free(path);
     }
+
+    fprintf(logfile, "Triggered log-dirty buffer switch\n");
     
     /* Read the required active buffer from the store */
     act = xs_read(xsh, XBT_NULL, next_active_path, &len);
diff --git a/tools/xcutils/xc_save.c b/tools/xcutils/xc_save.c
index 4bfcc67a8d..188ea7b72e 100644
--- a/tools/xcutils/xc_save.c
+++ b/tools/xcutils/xc_save.c
@@ -123,11 +123,13 @@ static void * init_qemu_maps(int domid, unsigned int bitmap_size)
     /* Tell qemu about it */
     if ((xs = xs_daemon_open()) == NULL)
         errx(1, "Couldn't contact xenstore");
-    if (!(path = xs_get_domain_path(xs, domid)))
+    if (!(path = strdup("/local/domain/0/device-model/")))
         errx(1, "can't get domain path in store");
     if (!(path = realloc(path, strlen(path) 
+                         + 10 
                          + strlen("/logdirty/next-active") + 1))) 
         errx(1, "no memory for constructing xenstore path");
+    snprintf(path + strlen(path), 11, "%i", domid);
     strcat(path, "/logdirty/");
     p = path + strlen(path);