conf: improve error log when PCI devices don't match requested controller

The virDomainPCIAddressFlagsCompatible() error logs report that a
device required a controller that accepted standard PCI endpoint
devices, or PCI Express endpoint devices, and if hotplug was required
by the configuration but not provided by the selected controller. But
the wording of the error messages was apparently confusing (according
to the bugzilla report referenced below). On top of that, if the
device was something other than an endpoint device (e.g. a
pcie-switch-downstream-port) the error message was a complete punt -
it would just say that the flags were incorrect.

This patch makes the messages for PCI/PCIe endpoint and hotplug
requirements more clear, and also specifically indicates what was the
device type when it is other than an endpoint device.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1363627

src/conf/domain_addr.c

@@ -118,38 +118,46 @@ virDomainPCIAddressFlagsCompatible(virPCIDeviceAddressPtr addr,
      * hot-plug and this bus doesn't have it, return false.
      */
     if (!(devFlags & busFlags & VIR_PCI_CONNECT_TYPES_MASK)) {
-        if (reportError) {
-            if (devFlags & VIR_PCI_CONNECT_TYPE_PCI_DEVICE) {
-                virReportError(errType,
-                               _("PCI bus is not compatible with the device "
-                                 "at %s. Device requires a standard PCI slot, "
-                                 "which is not provided by bus %.4x:%.2x"),
-                               addrStr, addr->domain, addr->bus);
-            } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCIE_DEVICE) {
-                virReportError(errType,
-                               _("PCI bus is not compatible with the device "
-                                 "at %s. Device requires a PCI Express slot, "
-                                 "which is not provided by bus %.4x:%.2x"),
-                               addrStr, addr->domain, addr->bus);
-            } else {
-                /* this should never happen. If it does, there is a
-                 * bug in the code that sets the flag bits for devices.
-                 */
-                virReportError(errType,
-                           _("The device information for %s has no PCI "
-                             "connection types listed"), addrStr);
-            }
+        const char *connectStr;
+
+        if (!reportError)
+            return false;
+
+        if (devFlags & VIR_PCI_CONNECT_TYPE_PCI_DEVICE) {
+            connectStr = "standard PCI device";
+        } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCIE_DEVICE) {
+            connectStr = "PCI Express device";
+        } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCIE_ROOT_PORT) {
+            connectStr = "pcie-root-port";
+        } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_UPSTREAM_PORT) {
+            connectStr = "pci-switch-upstream-port";
+        } else if (devFlags & VIR_PCI_CONNECT_TYPE_PCIE_SWITCH_DOWNSTREAM_PORT) {
+            connectStr = "pci-switch-downstream-port";
+        } else {
+            /* this should never happen. If it does, there is a
+             * bug in the code that sets the flag bits for devices.
+             */
+            virReportError(errType,
+                           _("The device at PCI address %s has "
+                             "unrecognized connection type flags 0x%.2x"),
+                           addrStr, devFlags & VIR_PCI_CONNECT_TYPES_MASK);
+            return false;
         }
+        virReportError(errType,
+                       _("The device at PCI address %s cannot be "
+                         "plugged into the PCI controller with index='%d'. "
+                         "It requires a controller that accepts a %s."),
+                       addrStr, addr->bus, connectStr);
         return false;
     }
     if ((devFlags & VIR_PCI_CONNECT_HOTPLUGGABLE) &&
         !(busFlags & VIR_PCI_CONNECT_HOTPLUGGABLE)) {
         if (reportError) {
             virReportError(errType,
-                           _("PCI bus is not compatible with the device "
-                             "at %s. Device requires hot-plug capability, "
-                             "which is not provided by bus %.4x:%.2x"),
-                           addrStr, addr->domain, addr->bus);
+                           _("The device at PCI address %s requires "
+                             "hotplug capability, but the PCI controller "
+                             "with index='%d' doesn't support hotplug"),
+                           addrStr, addr->bus);
         }
         return false;
     }