[Xen-devel] [RFC PATCH 6/6] libxl: create path for advertisement of network attributes...

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

...at vif instantiation time.

The xenstore path ~attr/vif/$DEVID is documented for the purposes of
a frontend advertising network attributes.

This patch adds an extra bool argument to libxl__device_generic_add()
(the function which creates frontend and backend xenstore paths) which
will cause creation of guest writable xenstore path ~/attr/$DEVICE/$DEVID
if true. libxl__device_nic_add() (i.e. $DEVICE == 'vif') is modified
to pass true for this argument. All other callers pass false.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl.c          | 18 ++++++++++++------
 tools/libxl/libxl_device.c   | 30 ++++++++++++++++++++++++------
 tools/libxl/libxl_internal.h |  5 ++++-
 tools/libxl/libxl_pci.c      |  3 ++-
 4 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index d7dd081..1689274 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2186,7 +2186,8 @@ void libxl__device_vtpm_add(libxl__egc *egc, uint32_t 
domid,
                                                              back->count),
                                   libxl__xs_kvs_of_flexarray(gc, front,
                                                              front->count),
-                                  NULL);
+                                  NULL,
+                                  false);
 
         rc = libxl__xs_transaction_commit(gc, &t);
         if (!rc) break;
@@ -2628,7 +2629,8 @@ static void device_disk_add(libxl__egc *egc, uint32_t 
domid,
         libxl__device_generic_add(gc, t, device,
                                   libxl__xs_kvs_of_flexarray(gc, back, 
back->count),
                                   libxl__xs_kvs_of_flexarray(gc, front, 
front->count),
-                                  NULL);
+                                  NULL,
+                                  false);
 
         rc = libxl__xs_transaction_commit(gc, &t);
         if (!rc) break;
@@ -3442,7 +3444,8 @@ void libxl__device_nic_add(libxl__egc *egc, uint32_t 
domid,
                                                              back->count),
                                   libxl__xs_kvs_of_flexarray(gc, front,
                                                              front->count),
-                                  NULL);
+                                  NULL,
+                                  true);
 
         rc = libxl__xs_transaction_commit(gc, &t);
         if (!rc) break;
@@ -3731,7 +3734,8 @@ int libxl__device_console_add(libxl__gc *gc, uint32_t 
domid,
     libxl__device_generic_add(gc, XBT_NULL, device,
                               libxl__xs_kvs_of_flexarray(gc, back, 
back->count),
                               libxl__xs_kvs_of_flexarray(gc, front, 
front->count),
-                              libxl__xs_kvs_of_flexarray(gc, ro_front, 
ro_front->count));
+                              libxl__xs_kvs_of_flexarray(gc, ro_front, 
ro_front->count),
+                              false);
     rc = 0;
 out:
     return rc;
@@ -4031,7 +4035,8 @@ int libxl__device_vkb_add(libxl__gc *gc, uint32_t domid,
     libxl__device_generic_add(gc, XBT_NULL, &device,
                               libxl__xs_kvs_of_flexarray(gc, back, 
back->count),
                               libxl__xs_kvs_of_flexarray(gc, front, 
front->count),
-                              NULL);
+                              NULL,
+                              false);
     rc = 0;
 out:
     return rc;
@@ -4144,7 +4149,8 @@ int libxl__device_vfb_add(libxl__gc *gc, uint32_t domid, 
libxl_device_vfb *vfb)
     libxl__device_generic_add(gc, XBT_NULL, &device,
                               libxl__xs_kvs_of_flexarray(gc, back, 
back->count),
                               libxl__xs_kvs_of_flexarray(gc, front, 
front->count),
-                              NULL);
+                              NULL,
+                              false);
     rc = 0;
 out:
     return rc;
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 8bb5e93..3b2cbcd 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -40,6 +40,15 @@ char *libxl__device_backend_path(libxl__gc *gc, 
libxl__device *device)
                      device->domid, device->devid);
 }
 
+char *libxl__device_attr_path(libxl__gc *gc, libxl__device *device)
+{
+    char *dom_path = libxl__xs_get_dompath(gc, device->domid);
+
+    return GCSPRINTF("%s/attr/%s/%d", dom_path,
+                     libxl__device_kind_to_string(device->kind),
+                     device->devid);
+}
+
 /* Returns 1 if device exists, 0 if not, ERROR_* (<0) on error. */
 int libxl__device_exists(libxl__gc *gc, xs_transaction_t t,
                          libxl__device *device)
@@ -102,22 +111,25 @@ out:
 }
 
 int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
-        libxl__device *device, char **bents, char **fents, char **ro_fents)
+                              libxl__device *device, char **bents, char 
**fents, char **ro_fents,
+                              bool attr)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
-    char *frontend_path, *backend_path;
+    char *frontend_path, *backend_path, *attr_path;
     struct xs_permissions frontend_perms[2];
     struct xs_permissions ro_frontend_perms[2];
     struct xs_permissions backend_perms[2];
+    struct xs_permissions attr_perms[2];
     int create_transaction = t == XBT_NULL;
 
     frontend_path = libxl__device_frontend_path(gc, device);
     backend_path = libxl__device_backend_path(gc, device);
+    attr_path = libxl__device_attr_path(gc, device);
 
-    frontend_perms[0].id = device->domid;
-    frontend_perms[0].perms = XS_PERM_NONE;
-    frontend_perms[1].id = device->backend_domid;
-    frontend_perms[1].perms = XS_PERM_READ;
+    attr_perms[0].id = frontend_perms[0].id = device->domid;
+    attr_perms[0].perms = frontend_perms[0].perms = XS_PERM_NONE;
+    attr_perms[1].id = frontend_perms[1].id = device->backend_domid;
+    attr_perms[1].perms = frontend_perms[1].perms = XS_PERM_READ;
 
     ro_frontend_perms[0].id = backend_perms[0].id = device->backend_domid;
     ro_frontend_perms[0].perms = backend_perms[0].perms = XS_PERM_NONE;
@@ -162,6 +174,12 @@ retry_transaction:
         libxl__xs_writev(gc, t, backend_path, bents);
     }
 
+    if (attr) {
+        xs_rm(ctx->xsh, t, attr_path);
+        xs_mkdir(ctx->xsh, t, attr_path);
+        xs_set_permissions(ctx->xsh, t, attr_path, attr_perms, 
ARRAY_SIZE(attr_perms));
+    }
+
     if (!create_transaction)
         return 0;
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index ab62e6f..89d893f 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1159,9 +1159,12 @@ _hidden int libxl__device_console_add(libxl__gc *gc, 
uint32_t domid,
 _hidden int libxl__device_exists(libxl__gc *gc, xs_transaction_t t,
                                  libxl__device *device);
 _hidden int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
-        libxl__device *device, char **bents, char **fents, char **ro_fents);
+                                      libxl__device *device, char **bents,
+                                      char **fents, char **ro_fents,
+                                      bool attr);
 _hidden char *libxl__device_backend_path(libxl__gc *gc, libxl__device *device);
 _hidden char *libxl__device_frontend_path(libxl__gc *gc, libxl__device 
*device);
+_hidden char *libxl__device_attr_path(libxl__gc *gc, libxl__device *device);
 _hidden int libxl__parse_backend_path(libxl__gc *gc, const char *path,
                                       libxl__device *dev);
 _hidden int libxl__device_destroy(libxl__gc *gc, libxl__device *dev);
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index de3976b..c175939 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -111,7 +111,8 @@ int libxl__create_pci_backend(libxl__gc *gc, uint32_t domid,
     libxl__device_generic_add(gc, XBT_NULL, &device,
                               libxl__xs_kvs_of_flexarray(gc, back, 
back->count),
                               libxl__xs_kvs_of_flexarray(gc, front, 
front->count),
-                              NULL);
+                              NULL,
+                              false);
 
     return 0;
 }
-- 
2.1.4


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