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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH RFC 09/12] libxl: add Qdisk backend launch helper
Current Qemu launch functions in libxl require the usage of data
structures only avaialbe on domain creation. All this information is
not need in order to launch a Qemu instance to serve Qdisk backends,
so introduce a new simplified helper that can be used to launch
Qemu/Qdisk, that will be used to launch Qdisk in driver domains.
Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
tools/libxl/libxl_dm.c | 149 +++++++++++++++++++++++++++++++++++++++---
tools/libxl/libxl_internal.h | 17 +++++
2 files changed, 157 insertions(+), 9 deletions(-)
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index ddc7367..01eb903 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1308,18 +1308,123 @@ static void device_model_spawn_outcome(libxl__egc *egc,
dmss->callback(egc, dmss, rc);
}
-int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
+/* callbacks passed in libxl__spawn_spawn for Qdisk attach */
+static void qdisk_confirm(libxl__egc *egc, libxl__spawn_state *spawn,
+ const char *xsdata);
+static void qdisk_startup_failed(libxl__egc *egc,
+ libxl__spawn_state *spawn);
+static void qdisk_detached(libxl__egc *egc,
+ libxl__spawn_state *spawn);
+
+void libxl__spawn_qdisk_backend(libxl__egc *egc, libxl__spawn_qdisk_state *sqs)
{
- char *pid;
- int ret;
+ STATE_AO_GC(sqs->spawn.ao);
+ flexarray_t *dm_args;
+ char **args;
+ char *logfile = NULL;
+ const char *dm;
+ int logfile_w, null, rc;
+ uint32_t domid = sqs->guest_domid;
+
+ /* Always use qemu-xen as device model */
+ dm = qemu_xen_path(gc);
+
+ dm_args = flexarray_make(gc, 15, 1);
+ flexarray_vappend(dm_args, dm, "-xen-domid",
+ GCSPRINTF("%d", domid), NULL);
+ flexarray_append(dm_args, "-xen-attach");
+ flexarray_vappend(dm_args, "-name",
+ GCSPRINTF("domain-%u", domid), NULL);
+ flexarray_append(dm_args, "-nographic");
+ flexarray_vappend(dm_args, "-M", "xenpv", NULL);
+ flexarray_vappend(dm_args, "-monitor", "/dev/null", NULL);
+ flexarray_vappend(dm_args, "-serial", "/dev/null", NULL);
+ flexarray_vappend(dm_args, "-parallel", "/dev/null", NULL);
+ flexarray_append(dm_args, NULL);
+ args = (char **) flexarray_contents(dm_args);
- pid = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc,
"/local/domain/%d/image/device-model-pid", domid));
- if (!pid || !atoi(pid)) {
- LOG(ERROR, "could not find device-model's pid for dom %u", domid);
- ret = ERROR_FAIL;
+ libxl_create_logfile(CTX, GCSPRINTF("qdisk-%u", domid), &logfile);
+ logfile_w = open(logfile, O_WRONLY|O_CREAT|O_APPEND, 0644);
+ if (logfile_w < 0) {
+ free(logfile);
+ rc = logfile_w;
+ goto error;
+ }
+ free(logfile);
+ null = open("/dev/null", O_RDONLY);
+
+ sqs->spawn.what = GCSPRINTF("domain %u Qdisk backend", domid);
+ sqs->spawn.xspath = GCSPRINTF("device-model/%u/state", domid);
+ sqs->spawn.timeout_ms = LIBXL_DEVICE_MODEL_START_TIMEOUT * 1000;
+ /*
+ * We cannot save Qemu pid anywhere in the xenstore guest dir,
+ * because we will call this from unprivileged driver domains,
+ * so save it in the current domain libxl private dir.
+ */
+ sqs->spawn.pidpath = GCSPRINTF("libxl/%u/qdisk-backend-pid", domid);
+ sqs->spawn.midproc_cb = libxl__spawn_record_pid;
+ sqs->spawn.confirm_cb = qdisk_confirm;
+ sqs->spawn.failure_cb = qdisk_startup_failed;
+ sqs->spawn.detached_cb = qdisk_detached;
+ rc = libxl__spawn_spawn(egc, &sqs->spawn);
+ if (rc < 0)
+ goto error;
+ if (!rc) { /* inner child */
+ setsid();
+ libxl__exec(gc, null, logfile_w, logfile_w, dm, args, NULL);
+ }
+
+ return;
+
+error:
+ assert(rc);
+ sqs->callback(egc, sqs, rc);
+ return;
+}
+
+static void qdisk_confirm(libxl__egc *egc, libxl__spawn_state *spawn,
+ const char *xsdata)
+{
+ STATE_AO_GC(spawn->ao);
+
+ if (!xsdata)
+ return;
+
+ if (strcmp(xsdata, "running"))
+ return;
+
+ libxl__spawn_initiate_detach(gc, spawn);
+}
+
+static void qdisk_startup_failed(libxl__egc *egc,
+ libxl__spawn_state *spawn)
+{
+ libxl__spawn_qdisk_state *sqs = CONTAINER_OF(spawn, *sqs, spawn);
+ sqs->callback(egc, sqs, ERROR_FAIL);
+}
+
+static void qdisk_detached(libxl__egc *egc,
+ libxl__spawn_state *spawn)
+{
+ libxl__spawn_qdisk_state *sqs = CONTAINER_OF(spawn, *sqs, spawn);
+ sqs->callback(egc, sqs, 0);
+}
+
+/* Generic function to signal a Qemu instance to exit */
+static int kill_device_model(libxl__gc *gc, const char *xs_path_pid)
+{
+ const char *xs_pid;
+ int ret, pid;
+
+ ret = libxl__xs_read_checked(gc, XBT_NULL, xs_path_pid, &xs_pid);
+ if (ret || !xs_pid) {
+ LOG(ERROR, "unable to find device model pid in %s", xs_path_pid);
+ ret = ret ? : ERROR_FAIL;
goto out;
}
- ret = kill(atoi(pid), SIGHUP);
+ pid = atoi(xs_pid);
+
+ ret = kill(pid, SIGHUP);
if (ret < 0 && errno == ESRCH) {
LOG(ERROR, "Device Model already exited");
ret = 0;
@@ -1327,7 +1432,7 @@ int libxl__destroy_device_model(libxl__gc *gc, uint32_t
domid)
LOG(DEBUG, "Device Model signaled");
ret = 0;
} else {
- LOGE(ERROR, "failed to kill Device Model [%d]", atoi(pid));
+ LOGE(ERROR, "failed to kill Device Model [%d]", pid);
ret = ERROR_FAIL;
goto out;
}
@@ -1336,6 +1441,32 @@ out:
return ret;
}
+/* Helper to destroy a Qdisk backend */
+int libxl__destroy_qdisk_backend(libxl__gc *gc, uint32_t domid)
+{
+ char *pid_path;
+ int rc;
+
+ pid_path = GCSPRINTF("libxl/%u/qdisk-backend-pid", domid);
+
+ rc = kill_device_model(gc, pid_path);
+ if (rc)
+ goto out;
+
+ libxl__xs_rm_checked(gc, XBT_NULL, pid_path);
+ libxl__xs_rm_checked(gc, XBT_NULL,
+ GCSPRINTF("device-model/%u", domid));
+
+out:
+ return rc;
+}
+
+int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
+{
+ return kill_device_model(gc,
+ GCSPRINTF("/local/domain/%d/image/device-model-pid", domid));
+}
+
int libxl__need_xenpv_qemu(libxl__gc *gc,
int nr_consoles, libxl__device_console *consoles,
int nr_vfbs, libxl_device_vfb *vfbs,
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 1746b7d..fe53b80 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2502,6 +2502,23 @@ _hidden void libxl__spawn_stub_dm(libxl__egc *egc,
libxl__stub_dm_spawn_state*);
_hidden char *libxl__stub_dm_name(libxl__gc *gc, const char * guest_name);
+/* Qdisk backend launch helpers */
+
+typedef struct libxl__spawn_qdisk_state libxl__spawn_qdisk_state;
+
+typedef void libxl__qdisk_spawn_cb(libxl__egc *egc, libxl__spawn_qdisk_state*,
+ int rc /* if !0, error was logged */);
+
+struct libxl__spawn_qdisk_state {
+ uint32_t guest_domid;
+ libxl__spawn_state spawn;
+ libxl__qdisk_spawn_cb *callback;
+};
+
+_hidden void libxl__spawn_qdisk_backend(libxl__egc *egc,
+ libxl__spawn_qdisk_state *sqs);
+_hidden int libxl__destroy_qdisk_backend(libxl__gc *gc, uint32_t domid);
+
/*----- Domain creation -----*/
typedef struct libxl__domain_create_state libxl__domain_create_state;
--
1.7.7.5 (Apple Git-26)
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