[Xen-devel] [PATCH v2 02/10] libxl: create a local xenstore libxl and device-model dir for guests

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

If libxl is executed inside a guest domain it needs write access to
the local libxl xenstore dir (/local/<domid>/libxl) to store internal
data. This also applies to Qemu which needs a
/local/<domid>/device-model xenstore directory.

This patch creates the mentioned directories for each guest launched
from libxl.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
Changes since v1:
 * Change documentation for the xs paths.
 * Add a "driver_domain" option that gates the creation of the
   specifc xs paths.

Changes since RFC:
 * Add documentation for the new paths.
---
 docs/man/xl.cfg.pod.5             |    5 +++++
 docs/misc/xenstore-paths.markdown |   10 ++++++++++
 tools/libxl/libxl.h               |    9 +++++++++
 tools/libxl/libxl_create.c        |   17 +++++++++++++++++
 tools/libxl/libxl_types.idl       |    1 +
 tools/libxl/xl_cmdimpl.c          |    2 ++
 6 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index d2d8921..d260895 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -307,6 +307,11 @@ which are incompatible with migration. Currently this is 
limited to
 enabling the invariant TSC feature flag in cpuid results when TSC is
 not emulated.
 
+=item B<driver_domain=BOOLEAN>
+
+Specify that this domain is a driver domain. This enables certain
+features needed in order to run a driver domain.
+
 =back
 
 =head2 Devices
diff --git a/docs/misc/xenstore-paths.markdown 
b/docs/misc/xenstore-paths.markdown
index 1c634b5..a0fc003 100644
--- a/docs/misc/xenstore-paths.markdown
+++ b/docs/misc/xenstore-paths.markdown
@@ -318,6 +318,16 @@ protocol definition.
 
 A domain writable path. Available for arbitrary domain use.
 
+### Paths private to the toolstack
+
+#### ~/device-model/$DOMID/state [w]
+
+Contains the status of the device models running on the domain.
+
+#### ~/libxl/$DOMID/qdisk-backend-pid [w]
+
+Contains the PIDs of the device models running on the domain.
+
 ## Virtual Machine Paths
 
 The /vm/$UUID namespace is used by toolstacks to store various
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 1c6675d..9e5651f 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -369,6 +369,15 @@
  */
 #define LIBXL_HAVE_DOMAIN_CREATE_RESTORE_PARAMS 1
 
+/*
+ * LIBXL_HAVE_DRIVER_DOMAIN_CREATION 1
+ *
+ * If this is defined, libxl_domain_create_info contains a driver_domain
+ * field that can be used to tell libxl that the domain that is going
+ * to be created is a driver domain, so the necessary actions are taken.
+ */
+#define LIBXL_HAVE_DRIVER_DOMAIN_CREATION 1
+
 /* Functions annotated with LIBXL_EXTERNAL_CALLERS_ONLY may not be
  * called from within libxl itself. Callers outside libxl, who
  * do not #include libxl_internal.h, are fine. */
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 9d793ba..4e2391d 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -36,6 +36,7 @@ int libxl__domain_create_info_setdefault(libxl__gc *gc,
     }
 
     libxl_defbool_setdefault(&c_info->run_hotplug_scripts, true);
+    libxl_defbool_setdefault(&c_info->driver_domain, false);
 
     return 0;
 }
@@ -533,6 +534,22 @@ retry_transaction:
     libxl__xs_mkdir(gc, t,
                     libxl__sprintf(gc, "%s/data", dom_path),
                     rwperm, ARRAY_SIZE(rwperm));
+
+    if (libxl_defbool_val(info->driver_domain)) {
+        /*
+         * Create a local "libxl" directory for each guest, since we might want
+         * to use libxl from inside the guest
+         */
+        libxl__xs_mkdir(gc, t, GCSPRINTF("%s/libxl", dom_path), rwperm,
+                        ARRAY_SIZE(rwperm));
+        /*
+         * Create a local "device-model" directory for each guest, since we
+         * might want to use Qemu from inside the guest
+         */
+        libxl__xs_mkdir(gc, t, GCSPRINTF("%s/device-model", dom_path), rwperm,
+                        ARRAY_SIZE(rwperm));
+    }
+
     if (info->type == LIBXL_DOMAIN_TYPE_HVM)
         libxl__xs_mkdir(gc, t,
             libxl__sprintf(gc, "%s/hvmloader/generation-id-address", dom_path),
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 5c43d6f..f9e4ea2 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -257,6 +257,7 @@ libxl_domain_create_info = Struct("domain_create_info",[
     ("platformdata", libxl_key_value_list),
     ("poolid",       uint32),
     ("run_hotplug_scripts",libxl_defbool),
+    ("driver_domain",libxl_defbool),
     ], dir=DIR_IN)
 
 libxl_domain_restore_params = Struct("domain_restore_params", [
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 40feb7d..b9831bc 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -848,6 +848,8 @@ static void parse_config_data(const char *config_source,
     if (!xlu_cfg_get_long(config, "max_event_channels", &l, 0))
         b_info->event_channels = l;
 
+    xlu_cfg_get_defbool(config, "driver_domain", &c_info->driver_domain, 0);
+
     switch(b_info->type) {
     case LIBXL_DOMAIN_TYPE_HVM:
         if (!xlu_cfg_get_string (config, "kernel", &buf, 0))
-- 
1.7.7.5 (Apple Git-26)


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