[Xen-devel] [PATCH 4/5] libxl: wait for stubdom to be ready

[Wei Liu <wei.liu2@xxxxxxxxxx>]

Watch /local/domain/$dm_domid/device-model/$domid/state, wait until
state turns "running" then unpause guest.

LIBXL_STUBDOM_START_TIMEOUT is the timeout used wait for stubdom to be
ready. My test on a very old machine (Core 2 6400) showed that it might
need more than 20s before the stubdom is ready to serve DomU.

Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl_dm.c       | 39 ++++++++++++++++++++++++++++++++++++++-
 tools/libxl/libxl_internal.h |  2 ++
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 4a38455..ad2ef41 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -984,6 +984,8 @@ static void stubdom_pvqemu_cb(libxl__egc *egc,
 static void spawn_stubdom_pvqemu_destroy_cb(libxl__egc *egc,
                                             libxl__destroy_domid_state *dis,
                                             int rc);
+static void stubdom_xswait_cb(libxl__egc *egc, libxl__xswait_state *xswait,
+                              int rc, const char *p);
 
 char *libxl__stub_dm_name(libxl__gc *gc, const char *guest_name)
 {
@@ -1273,16 +1275,51 @@ static void stubdom_pvqemu_cb(libxl__egc *egc,
     rc = libxl_domain_unpause(CTX, dm_domid);
     if (rc) goto out;
 
+    libxl__xswait_init(&sdss->xswait);
+    sdss->xswait.ao = ao;
+    sdss->xswait.what = GCSPRINTF("Stubdom %d startup", dm_domid);
+    sdss->xswait.path = GCSPRINTF("/local/domain/%u/device-model/%u/state",
+                                  dm_domid, sdss->dm.guest_domid);
+    sdss->xswait.timeout_ms = LIBXL_STUBDOM_START_TIMEOUT * 1000;
+    sdss->xswait.callback = stubdom_xswait_cb;
+    rc = libxl__xswait_start(gc, &sdss->xswait);
+    if (rc) goto out;
+
+    return;
+
+ out:
+    stubdom_xswait_cb(egc, &sdss->xswait, rc, NULL);
+}
+
+static void stubdom_xswait_cb(libxl__egc *egc, libxl__xswait_state *xswait,
+                              int rc, const char *p)
+{
+    EGC_GC;
+    libxl__stub_dm_spawn_state *sdss = CONTAINER_OF(xswait, *sdss, xswait);
+    uint32_t dm_domid = sdss->pvqemu.guest_domid;
+
+    if (rc) {
+        if (rc == ERROR_TIMEDOUT)
+            LOG(ERROR, "%s: startup timed out", xswait->what);
+        goto out;
+    }
+
+    if (!p) return;
+
+    if (strcmp(p, "running"))
+        return;
  out:
     if (rc) {
         if (dm_domid) {
-            sdss->dis.ao = ao;
+            sdss->dis.ao = sdss->dm.spawn.ao;
             sdss->dis.domid = dm_domid;
             sdss->dis.callback = spawn_stubdom_pvqemu_destroy_cb;
             libxl__destroy_domid(egc, &sdss->dis);
+            libxl__xswait_stop(gc, xswait);
             return;
         }
     }
+    libxl__xswait_stop(gc, xswait);
     sdss->callback(egc, &sdss->dm, rc);
 }
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 934465a..3e06514 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -86,6 +86,7 @@
 #define LIBXL_DESTROY_TIMEOUT 10
 #define LIBXL_HOTPLUG_TIMEOUT 10
 #define LIBXL_DEVICE_MODEL_START_TIMEOUT 10
+#define LIBXL_STUBDOM_START_TIMEOUT 30
 #define LIBXL_QEMU_BODGE_TIMEOUT 2
 #define LIBXL_XENCONSOLE_LIMIT 1048576
 #define LIBXL_XENCONSOLE_PROTOCOL "vt100"
@@ -3044,6 +3045,7 @@ typedef struct {
     libxl__dm_spawn_state pvqemu;
     libxl__destroy_domid_state dis;
     libxl__multidev multidev;
+    libxl__xswait_state xswait;
 } libxl__stub_dm_spawn_state;
 
 _hidden void libxl__spawn_stub_dm(libxl__egc *egc, 
libxl__stub_dm_spawn_state*);
-- 
1.9.1


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