[Xen-devel] [PATCH v1 04/12] 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 RFC:
 * Add documentation for the new paths.
---
 docs/misc/xenstore-paths.markdown |   10 ++++++++++
 tools/libxl/libxl_create.c        |   12 ++++++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/docs/misc/xenstore-paths.markdown 
b/docs/misc/xenstore-paths.markdown
index 1c634b5..a8c4c58 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.
 
+### Driver domain specific paths
+
+#### ~/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_create.c b/tools/libxl/libxl_create.c
index 0c32d0b..aac19b5 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -498,6 +498,18 @@ retry_transaction:
     libxl__xs_mkdir(gc, t,
                     libxl__sprintf(gc, "%s/data", dom_path),
                     rwperm, ARRAY_SIZE(rwperm));
+    /*
+     * 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),
-- 
1.7.7.5 (Apple Git-26)


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