hostdev: Emit debug messages while handling PCI hostdevs

Both detach and reattach are complex operations involving several steps,
and it can be useful to be able to follow along by reading the log.

src/util/virhostdev.c

@@ -596,11 +596,17 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
 
-        if (virPCIDeviceGetManaged(dev) &&
-            virPCIDeviceDetach(dev,
+        if (virPCIDeviceGetManaged(dev)) {
+            VIR_DEBUG("Detaching managed PCI device %s",
+                      virPCIDeviceGetName(dev));
+            if (virPCIDeviceDetach(dev,
                                    hostdev_mgr->activePCIHostdevs,
                                    hostdev_mgr->inactivePCIHostdevs) < 0)
                 goto reattachdevs;
+        } else {
+            VIR_DEBUG("Not detaching unmanaged PCI device %s",
+                      virPCIDeviceGetName(dev));
+        }
     }
 
     /* At this point, all devices are attached to the stub driver and have
@@ -611,6 +617,7 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
 
+        VIR_DEBUG("Resetting PCI device %s", virPCIDeviceGetName(dev));
         if (virPCIDeviceReset(dev, hostdev_mgr->activePCIHostdevs,
                               hostdev_mgr->inactivePCIHostdevs) < 0)
             goto reattachdevs;
@@ -632,6 +639,9 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
     /* Loop 5: Now mark all the devices as active */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
+
+        VIR_DEBUG("Adding PCI device %s to active list",
+                  virPCIDeviceGetName(dev));
         if (virPCIDeviceListAdd(hostdev_mgr->activePCIHostdevs, dev) < 0)
             goto inactivedevs;
     }
@@ -639,6 +649,9 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
     /* Loop 6: Now remove the devices from inactive list. */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
+
+        VIR_DEBUG("Removing PCI device %s from inactive list",
+                  virPCIDeviceGetName(dev));
         virPCIDeviceListDel(hostdev_mgr->inactivePCIHostdevs, dev);
     }
 
@@ -651,6 +664,8 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
         dev = virPCIDeviceListGet(pcidevs, i);
         activeDev = virPCIDeviceListFind(hostdev_mgr->activePCIHostdevs, dev);
 
+        VIR_DEBUG("Setting driver and domain information for PCI device %s",
+                  virPCIDeviceGetName(dev));
         if (activeDev)
             virPCIDeviceSetUsedBy(activeDev, drv_name, dom_name);
     }
@@ -674,6 +689,8 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
          * "reprobe" were already set by pciDettachDevice in
          * loop 2.
          */
+        VIR_DEBUG("Saving network configuration of PCI device %s",
+                  virPCIDeviceGetName(dev));
         if ((pcidev = virPCIDeviceListFind(pcidevs, dev))) {
             hostdev->origstates.states.pci.unbind_from_stub =
                 virPCIDeviceGetUnbindFromStub(pcidev);
@@ -699,6 +716,9 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
      */
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
+
+        VIR_DEBUG("Removing PCI device %s from active list",
+                  virPCIDeviceGetName(dev));
         virPCIDeviceListSteal(hostdev_mgr->activePCIHostdevs, dev);
     }
 
@@ -715,9 +735,14 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
             /* NB: This doesn't actually re-bind to original driver, just
              * unbinds from the stub driver
              */
+            VIR_DEBUG("Reattaching managed PCI device %s",
+                      virPCIDeviceGetName(dev));
             ignore_value(virPCIDeviceReattach(dev,
                                               hostdev_mgr->activePCIHostdevs,
                                               hostdev_mgr->inactivePCIHostdevs));
+        } else {
+            VIR_DEBUG("Not reattaching unmanaged PCI device %s",
+                      virPCIDeviceGetName(dev));
         }
     }
 
@@ -739,6 +764,8 @@ virHostdevReattachPCIDevice(virPCIDevicePtr dev, virHostdevManagerPtr mgr)
      * successfully, it must have been inactive.
      */
     if (!virPCIDeviceGetManaged(dev)) {
+        VIR_DEBUG("Adding unmanaged PCI device %s to inactive list",
+                  virPCIDeviceGetName(dev));
         if (virPCIDeviceListAdd(mgr->inactivePCIHostdevs, dev) < 0)
             virPCIDeviceFree(dev);
         return;
@@ -754,6 +781,7 @@ virHostdevReattachPCIDevice(virPCIDevicePtr dev, virHostdevManagerPtr mgr)
         }
     }
 
+    VIR_DEBUG("Reattaching PCI device %s", virPCIDeviceGetName(dev));
     if (virPCIDeviceReattach(dev, mgr->activePCIHostdevs,
                              mgr->inactivePCIHostdevs) < 0) {
         virErrorPtr err = virGetLastError();
@@ -821,6 +849,8 @@ virHostdevReAttachPCIDevices(virHostdevManagerPtr hostdev_mgr,
                 }
         }
 
+        VIR_DEBUG("Removing PCI device %s from active list",
+                  virPCIDeviceGetName(dev));
         virPCIDeviceListDel(hostdev_mgr->activePCIHostdevs, dev);
         i++;
     }
@@ -843,6 +873,8 @@ virHostdevReAttachPCIDevices(virHostdevManagerPtr hostdev_mgr,
                                   pcisrc->addr.slot, pcisrc->addr.function);
             if (dev) {
                 if (virPCIDeviceListFind(pcidevs, dev)) {
+                    VIR_DEBUG("Restoring network configuration of PCI device %s",
+                              virPCIDeviceGetName(dev));
                     virHostdevNetConfigRestore(hostdev, hostdev_mgr->stateDir,
                                                oldStateDir);
                 }
@@ -855,6 +887,7 @@ virHostdevReAttachPCIDevices(virHostdevManagerPtr hostdev_mgr,
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
 
+        VIR_DEBUG("Resetting PCI device %s", virPCIDeviceGetName(dev));
         if (virPCIDeviceReset(dev, hostdev_mgr->activePCIHostdevs,
                               hostdev_mgr->inactivePCIHostdevs) < 0) {
             virErrorPtr err = virGetLastError();