[PATCH v2 14/24] libxl: Make sure devices added by pci-attach are reflected in the config

[Paul Durrant <paul@xxxxxxx>]

From: Paul Durrant <pdurrant@xxxxxxxxxx>

Currently libxl__device_pci_add_xenstore() is broken in that does not
update the domain's configuration for the first device added (which causes
creation of the overall backend area in xenstore). This can be easily observed
by running 'xl list -l' after adding a single device: the device will be
missing.

This patch fixes the problem and adds a DEBUG log line to allow easy
verification that the domain configuration is being modified.

NOTE: This patch includes a whitespace in add_pcis_done().

Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
---
Cc: Ian Jackson <iwj@xxxxxxxxxxxxxx>
Cc: Wei Liu <wl@xxxxxxx>

v2:
 - Avoid having two completely different ways of adding devices into xenstore
---
 tools/libs/light/libxl_pci.c | 71 +++++++++++-------------------------
 1 file changed, 21 insertions(+), 50 deletions(-)

diff --git a/tools/libs/light/libxl_pci.c b/tools/libs/light/libxl_pci.c
index 06fdc50ce10c..29a450f7e649 100644
--- a/tools/libs/light/libxl_pci.c
+++ b/tools/libs/light/libxl_pci.c
@@ -79,39 +79,18 @@ static void libxl__device_from_pci(libxl__gc *gc, uint32_t 
domid,
     device->kind = LIBXL__DEVICE_KIND_PCI;
 }
 
-static int libxl__create_pci_backend(libxl__gc *gc, uint32_t domid,
-                                     const libxl_device_pci *pci,
-                                     int num)
+static void libxl__create_pci_backend(libxl__gc *gc, uint32_t domid,
+                                      flexarray_t *front, flexarray_t *back)
 {
-    flexarray_t *front = NULL;
-    flexarray_t *back = NULL;
-    libxl__device device;
-    int i;
-
-    front = flexarray_make(gc, 16, 1);
-    back = flexarray_make(gc, 16, 1);
-
     LOGD(DEBUG, domid, "Creating pci backend");
 
-    /* add pci device */
-    libxl__device_from_pci(gc, domid, pci, &device);
-
     flexarray_append_pair(back, "frontend-id", GCSPRINTF("%d", domid));
-    flexarray_append_pair(back, "online", "1");
+    flexarray_append_pair(back, "online", GCSPRINTF("%d", 1));
     flexarray_append_pair(back, "state", GCSPRINTF("%d", 
XenbusStateInitialising));
     flexarray_append_pair(back, "domain", libxl__domid_to_name(gc, domid));
 
-    for (i = 0; i < num; i++, pci++)
-        libxl_create_pci_backend_device(gc, back, i, pci);
-
-    flexarray_append_pair(back, "num_devs", GCSPRINTF("%d", num));
     flexarray_append_pair(front, "backend-id", GCSPRINTF("%d", 0));
     flexarray_append_pair(front, "state", GCSPRINTF("%d", 
XenbusStateInitialising));
-
-    return libxl__device_generic_add(gc, XBT_NULL, &device,
-                                     libxl__xs_kvs_of_flexarray(gc, back),
-                                     libxl__xs_kvs_of_flexarray(gc, front),
-                                     NULL);
 }
 
 static int libxl__device_pci_add_xenstore(libxl__gc *gc,
@@ -119,7 +98,7 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
                                           const libxl_device_pci *pci,
                                           bool starting)
 {
-    flexarray_t *back;
+    flexarray_t *front, *back;
     char *num_devs, *be_path;
     int num = 0;
     xs_transaction_t t = XBT_NULL;
@@ -127,16 +106,22 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
     libxl_domain_config d_config;
     libxl__flock *lock = NULL;
     bool is_stubdomain = libxl_is_stubdom(CTX, domid, NULL);
+    libxl__device device;
+
+    libxl__device_from_pci(gc, domid, pci, &device);
 
     /* Stubdomain doesn't have own config. */
     if (!is_stubdomain)
         libxl_domain_config_init(&d_config);
 
+    front = flexarray_make(gc, 16, 1);
+    back = flexarray_make(gc, 16, 1);
+
     be_path = libxl__domain_device_backend_path(gc, 0, domid, 0,
                                                 LIBXL__DEVICE_KIND_PCI);
     num_devs = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/num_devs", be_path));
     if (!num_devs)
-        return libxl__create_pci_backend(gc, domid, pci, 1);
+        libxl__create_pci_backend(gc, domid, front, back);
 
     libxl_domain_type domtype = libxl__domain_type(gc, domid);
     if (domtype == LIBXL_DOMAIN_TYPE_INVALID)
@@ -147,20 +132,18 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
             return ERROR_FAIL;
     }
 
-    back = flexarray_make(gc, 16, 1);
-
     LOGD(DEBUG, domid, "Adding new pci device to xenstore");
-    num = atoi(num_devs);
+    num = num_devs ? atoi(num_devs) : 0;
     libxl_create_pci_backend_device(gc, back, num, pci);
     flexarray_append_pair(back, "num_devs", GCSPRINTF("%d", num + 1));
-    if (!starting)
+    if (num && !starting)
         flexarray_append_pair(back, "state", GCSPRINTF("%d", 
XenbusStateReconfiguring));
 
     /*
      * Stubdomin config is derived from its target domain, it doesn't have
      * its own file.
      */
-    if (!is_stubdomain) {
+    if (!is_stubdomain && !starting) {
         lock = libxl__lock_domain_userdata(gc, domid);
         if (!lock) {
             rc = ERROR_LOCK_FAIL;
@@ -170,6 +153,7 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
         rc = libxl__get_domain_configuration(gc, domid, &d_config);
         if (rc) goto out;
 
+        LOGD(DEBUG, domid, "Adding new pci device to config");
         device_add_domain_config(gc, &d_config, &libxl__pci_devtype,
                                  pci);
 
@@ -186,7 +170,10 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
             if (rc) goto out;
         }
 
-        libxl__xs_writev(gc, t, be_path, libxl__xs_kvs_of_flexarray(gc, back));
+        libxl__device_generic_add(gc, t, &device,
+                                  libxl__xs_kvs_of_flexarray(gc, back),
+                                  libxl__xs_kvs_of_flexarray(gc, front),
+                                  NULL);
 
         rc = libxl__xs_transaction_commit(gc, &t);
         if (!rc) break;
@@ -1390,7 +1377,7 @@ out_no_irq:
         }
     }
 
-    if (!starting && !libxl_get_stubdom_id(CTX, domid))
+    if (!libxl_get_stubdom_id(CTX, domid))
         rc = libxl__device_pci_add_xenstore(gc, domid, pci, starting);
     else
         rc = 0;
@@ -1699,28 +1686,12 @@ static void libxl__add_pcis(libxl__egc *egc, libxl__ao 
*ao, uint32_t domid,
 }
 
 static void add_pcis_done(libxl__egc *egc, libxl__multidev *multidev,
-                             int rc)
+                          int rc)
 {
     EGC_GC;
     add_pcis_state *apds = CONTAINER_OF(multidev, *apds, multidev);
-
-    /* Convenience aliases */
-    libxl_domain_config *d_config = apds->d_config;
-    libxl_domid domid = apds->domid;
     libxl__ao_device *aodev = apds->outer_aodev;
 
-    if (rc) goto out;
-
-    if (d_config->num_pcis > 0 && !libxl_get_stubdom_id(CTX, domid)) {
-        rc = libxl__create_pci_backend(gc, domid, d_config->pcis,
-                                       d_config->num_pcis);
-        if (rc < 0) {
-            LOGD(ERROR, domid, "libxl_create_pci_backend failed: %d", rc);
-            goto out;
-        }
-    }
-
-out:
     aodev->rc = rc;
     aodev->callback(egc, aodev);
 }
-- 
2.20.1