[libvirt PATCH 1/2] nodedev: fix parent device of inactive mdevs

[Jonathon Jongsma]

Inactive mdevs were simply formatting their parent name as the value
received from mdevctl rather than looking up the libvirt nodedev name of
the parent device. This resulted in a parent value of e.g.
'0000:5b:00.0' instead of 'pci_0000_5b_00_0'. This prevented defining a
new mdev device from the output of nodedev-dumpxml.

Unfortunately, it's not simple to fix this comprehensively due to the
fact that mdevctl supports defining (inactive) mdevs for parent devices
that do not actually exist on the host (yet). So for those persistent
mdev definitions that do not have a valid parent in the device list, the
parent device will be set to the root "computer" device.

Unfortunately, because the value of the 'parent' field now depends on
the configuration of the host, the mdevctl parsing test will output
'computer' for all test devices. Fixing this would require a more
extensive mock test environment.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1979761

Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>

fixup
---
 src/node_device/node_device_driver.c          | 20 ++++++++++++++++++-
 .../mdevctl-list-multiple.out.xml             |  8 ++++----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/node_device/node_device_driver.c b/src/node_device/node_device_driver.c
index b4dd57e5f4..26b0c2f032 100644
--- a/src/node_device/node_device_driver.c
+++ b/src/node_device/node_device_driver.c
@@ -1051,6 +1051,7 @@ nodeDeviceParseMdevctlChildDevice(const char *parent,
     virJSONValue *props;
     virJSONValue *attrs;
     g_autoptr(virNodeDeviceDef) child = g_new0(virNodeDeviceDef, 1);
+    g_autofree char *parent_sysfs_path = NULL;
 
     /* the child object should have a single key equal to its uuid.
      * The value is an object describing the properties of the mdev */
@@ -1060,7 +1061,24 @@ nodeDeviceParseMdevctlChildDevice(const char *parent,
     uuid = virJSONValueObjectGetKey(json, 0);
     props = virJSONValueObjectGetValue(json, 0);
 
-    child->parent = g_strdup(parent);
+    /* Look up id of parent device. mdevctl supports defining mdevs for parent
+     * devices that are not present on the system (to support starting mdevs on
+     * hotplug, etc) so the parent may not actually exist. */
+    parent_sysfs_path = g_strdup_printf("/sys/class/mdev_bus/%s", parent);
+    if (virFileExists(parent_sysfs_path)) {
+        g_autofree char *canon_syspath = realpath(parent_sysfs_path, NULL);
+        virNodeDeviceObj *parentobj = NULL;
+        if ((parentobj = virNodeDeviceObjListFindBySysfsPath(driver->devs,
+                                                             canon_syspath))) {
+            virNodeDeviceDef *parentdef = virNodeDeviceObjGetDef(parentobj);
+            child->parent = g_strdup(parentdef->name);
+            virNodeDeviceObjEndAPI(&parentobj);
+
+            child->parent_sysfs_path = g_steal_pointer(&canon_syspath);
+        }
+    }
+    if (!child->parent)
+        child->parent = g_strdup("computer");
     child->caps = g_new0(virNodeDevCapsDef, 1);
     child->caps->data.type = VIR_NODE_DEV_CAP_MDEV;
 
diff --git a/tests/nodedevmdevctldata/mdevctl-list-multiple.out.xml b/tests/nodedevmdevctldata/mdevctl-list-multiple.out.xml
index cf7e966256..eead6f2a40 100644
--- a/tests/nodedevmdevctldata/mdevctl-list-multiple.out.xml
+++ b/tests/nodedevmdevctldata/mdevctl-list-multiple.out.xml
@@ -1,6 +1,6 @@
 <device>
   <name>mdev_200f228a_c80a_4d50_bfb7_f5a0e4e34045</name>
-  <parent>0000:00:02.0</parent>
+  <parent>computer</parent>
   <capability type='mdev'>
     <type id='i915-GVTg_V5_4'/>
     <uuid>200f228a-c80a-4d50-bfb7-f5a0e4e34045</uuid>
@@ -9,7 +9,7 @@
 </device>
 <device>
   <name>mdev_de807ffc_1923_4d5f_b6c9_b20ecebc6d4b</name>
-  <parent>0000:00:02.0</parent>
+  <parent>computer</parent>
   <capability type='mdev'>
     <type id='i915-GVTg_V5_4'/>
     <uuid>de807ffc-1923-4d5f-b6c9-b20ecebc6d4b</uuid>
@@ -18,7 +18,7 @@
 </device>
 <device>
   <name>mdev_435722ea_5f43_468a_874f_da34f1217f13</name>
-  <parent>0000:00:02.0</parent>
+  <parent>computer</parent>
   <capability type='mdev'>
     <type id='i915-GVTg_V5_8'/>
     <uuid>435722ea-5f43-468a-874f-da34f1217f13</uuid>
@@ -28,7 +28,7 @@
 </device>
 <device>
   <name>mdev_783e6dbb_ea0e_411f_94e2_717eaad438bf</name>
-  <parent>matrix</parent>
+  <parent>computer</parent>
   <capability type='mdev'>
     <type id='vfio_ap-passthrough'/>
     <uuid>783e6dbb-ea0e-411f-94e2-717eaad438bf</uuid>
-- 
2.31.1