libxl: add option to choose who executes hotplug scripts

Add and option to xl.conf file to decide if hotplug scripts are
executed from the toolstack (xl) or from udev as it used to be in the
past.

This option is only introduced in this patch, but it has no effect
since the code to call hotplug scripts from libxl is introduced in a
latter patch.

This choice will be saved in "libxl/disable_udev", as specified in the
DISABLE_UDEV_PATH constant.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

10 files changed, 84 insertions, 1 deletions

diff --git a/docs/man/xl.conf.pod.5 b/docs/man/xl.conf.pod.5
index 149430c61e..23932bea63 100644
--- a/docs/man/xl.conf.pod.5
+++ b/docs/man/xl.conf.pod.5
@@ -55,6 +55,14 @@ default.
 
 Default: C<1>
 
+=item B<run_hotplug_scripts=BOOLEAN>
+
+If disabled hotplug scripts will be called from udev, as it used to
+be in the previous releases. With the default option, hotplug scripts
+will be launched by xl directly.
+
+Default: C<1>
+
 =item B<lockfile="PATH">
 
 Sets the path to the lock file used by xl to serialise certain
diff --git a/tools/examples/xl.conf b/tools/examples/xl.conf
index ebf057c37a..28ab796ea3 100644
--- a/tools/examples/xl.conf
+++ b/tools/examples/xl.conf
@@ -15,3 +15,8 @@
 
 # first block device to be used for temporary VM disk mounts
 #blkdev_start="xvda"
+
+# default option to run hotplug scripts from xl
+# if disabled the old behaviour will be used, and hotplug scripts will be
+# launched by udev.
+#run_hotplug_scripts=1
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 707e7dd728..b9dd547c6a 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -70,6 +70,8 @@ int libxl__domain_create_info_setdefault(libxl__gc *gc,
         libxl_defbool_setdefault(&c_info->oos, true);
     }
 
+    libxl_defbool_setdefault(&c_info->run_hotplug_scripts, true);
+
     return 0;
 }
 
@@ -384,7 +386,7 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_create_info *info,
                        uint32_t *domid)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
-    int flags, ret, rc;
+    int flags, ret, rc, nb_vm;
     char *uuid_string;
     char *dom_path, *vm_path, *libxl_path;
     struct xs_permissions roperm[2];
@@ -392,6 +394,7 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_create_info *info,
     struct xs_permissions noperm[1];
     xs_transaction_t t = 0;
     xen_domain_handle_t handle;
+    libxl_vminfo *vm_list;
 
 
     assert(!libxl_domid_valid_guest(*domid));
@@ -505,6 +508,41 @@ retry_transaction:
             libxl__sprintf(gc, "%s/hvmloader/generation-id-address", dom_path),
                         rwperm, ARRAY_SIZE(rwperm));
 
+                    vm_list = libxl_list_vm(ctx, &nb_vm);
+    if (!vm_list) {
+        LOG(ERROR, "cannot get number of running guests");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    libxl_vminfo_list_free(vm_list, nb_vm);
+    int hotplug_setting = libxl__hotplug_settings(gc, t);
+    if (hotplug_setting < 0) {
+        LOG(ERROR, "unable to get current hotplug scripts execution setting");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    if (libxl_defbool_val(info->run_hotplug_scripts) != hotplug_setting &&
+        (nb_vm - 1)) {
+        LOG(ERROR, "cannot change hotplug execution option once set, "
+                    "please shutdown all guests before changing it");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    if (libxl_defbool_val(info->run_hotplug_scripts)) {
+        rc = libxl__xs_write_checked(gc, t, DISABLE_UDEV_PATH, "1");
+        if (rc) {
+            LOGE(ERROR, "unable to write %s = 1", DISABLE_UDEV_PATH);
+            goto out;
+        }
+    } else {
+        rc = libxl__xs_rm_checked(gc, t, DISABLE_UDEV_PATH);
+        if (rc) {
+            LOGE(ERROR, "unable to delete %s", DISABLE_UDEV_PATH);
+            goto out;
+        }
+    }
+
     xs_write(ctx->xsh, t, libxl__sprintf(gc, "%s/uuid", vm_path), uuid_string, strlen(uuid_string));
     xs_write(ctx->xsh, t, libxl__sprintf(gc, "%s/name", vm_path), info->name, strlen(info->name));
 
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 1b17ef516f..dec7c19661 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -785,6 +785,9 @@ void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
 
     libxl__dm_vifs_from_hvm_guest_config(gc, guest_config, dm_config);
 
+    dm_config->c_info.run_hotplug_scripts =
+        guest_config->c_info.run_hotplug_scripts;
+
     ret = libxl__domain_create_info_setdefault(gc, &dm_config->c_info);
     if (ret) goto out;
     ret = libxl__domain_build_info_setdefault(gc, &dm_config->b_info);
diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index 24099f59f6..211c8f5e2f 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -352,6 +352,25 @@ int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid)
     return value;
 }
 
+int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t)
+{
+    int rc = 0;
+    char *val;
+
+    val = libxl__xs_read(gc, t, DISABLE_UDEV_PATH);
+    if (!val && errno != ENOENT) {
+        LOGE(ERROR, "cannot read %s from xenstore", DISABLE_UDEV_PATH);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    if (!val) val = "0";
+
+    rc = !!atoi(val);
+
+out:
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index e89f37c296..1ac681db55 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -91,6 +91,7 @@
 #define STUBDOM_CONSOLE_SERIAL 3
 #define STUBDOM_SPECIAL_CONSOLES 3
 #define TAP_DEVICE_SUFFIX "-emu"
+#define DISABLE_UDEV_PATH "libxl/disable_udev"
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
 
@@ -1510,6 +1511,8 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc *gc, const char *s);
    * default is qemu xen traditional */
 _hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
 
+/* Check how executes hotplug script currently */
+int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t);
 
 /*
  * Calling context and GC for event-generating functions:
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index c1815c6c00..daa8c790ed 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -231,6 +231,7 @@ libxl_domain_create_info = Struct("domain_create_info",[
     ("xsdata",       libxl_key_value_list),
     ("platformdata", libxl_key_value_list),
     ("poolid",       uint32),
+    ("run_hotplug_scripts",libxl_defbool),
     ], dir=DIR_IN)
 
 MemKB = UInt(64, init_val = "LIBXL_MEMKB_DEFAULT")
diff --git a/tools/libxl/xl.c b/tools/libxl/xl.c
index d6f2b3ead2..f31e836e87 100644
--- a/tools/libxl/xl.c
+++ b/tools/libxl/xl.c
@@ -39,6 +39,7 @@ int dryrun_only;
 int force_execution;
 int autoballoon = 1;
 char *blkdev_start;
+int run_hotplug_scripts = 1;
 char *lockfile;
 char *default_vifscript = NULL;
 char *default_bridge = NULL;
@@ -70,6 +71,9 @@ static void parse_global_config(const char *configfile,
     if (!xlu_cfg_get_long (config, "autoballoon", &l, 0))
         autoballoon = l;
 
+    if (!xlu_cfg_get_long (config, "run_hotplug_scripts", &l, 0))
+        run_hotplug_scripts = l;
+
     if (!xlu_cfg_get_string (config, "lockfile", &buf, 0))
         lockfile = strdup(buf);
     else {
diff --git a/tools/libxl/xl.h b/tools/libxl/xl.h
index b0ba357d3c..0b2f848f90 100644
--- a/tools/libxl/xl.h
+++ b/tools/libxl/xl.h
@@ -140,6 +140,7 @@ int xl_child_pid(xlchildnum); /* returns 0 if child struct is not in use */
 
 /* global options */
 extern int autoballoon;
+extern int run_hotplug_scripts;
 extern int dryrun_only;
 extern char *lockfile;
 extern char *default_vifscript;
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 72892f3dfd..a7dc3403d1 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -595,6 +595,7 @@ static void parse_config_data(const char *config_source,
         }
     }
 
+    libxl_defbool_set(&c_info->run_hotplug_scripts, run_hotplug_scripts);
     c_info->type = LIBXL_DOMAIN_TYPE_PV;
     if (!xlu_cfg_get_string (config, "builder", &buf, 0) &&
         !strncmp(buf, "hvm", strlen(buf)))