diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 67340b65d67b19371a6b13847ad7c58c567870f4..a48e6f139a1537b8fea8a27dff230ea06ec635da 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -4401,12 +4401,6 @@ qemuDomainDeviceDefValidateControllerPCIOld(const virDomainControllerDef *contro
         break;
 
     case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT:
-        if (pciopts->targetIndex == -1) {
-            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                           _("autogenerated pci-root options not set"));
-            return -1;
-        }
-
         /* Skip the implicit one */
         if (pciopts->targetIndex == 0)
             return 0;
@@ -4637,6 +4631,46 @@ qemuDomainDeviceDefValidateControllerPCI(const virDomainControllerDef *cont,
         return -1;
     }
 
+    /* targetIndex */
+    switch ((virDomainControllerModelPCI) cont->model) {
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_ROOT:
+        /* PHBs for pSeries guests must have been assigned a targetIndex */
+        if (pciopts->targetIndex == -1 &&
+            pciopts->modelName == VIR_DOMAIN_CONTROLLER_PCI_MODEL_NAME_SPAPR_PCI_HOST_BRIDGE) {
+            virReportControllerMissingOption(cont, model, modelName, "targetIndex");
+            return -1;
+        }
+
+        /* targetIndex only applies to PHBs, so for any other pci-root
+         * controller it being present is an error */
+        if (pciopts->targetIndex != -1 &&
+            pciopts->modelName != VIR_DOMAIN_CONTROLLER_PCI_MODEL_NAME_SPAPR_PCI_HOST_BRIDGE) {
+            virReportControllerInvalidOption(cont, model, modelName, "targetIndex");
+            return -1;
+        }
+        break;
+
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_BRIDGE:
+    case VIR_DOMAIN_CONTROLLER_MODEL_DMI_TO_PCI_BRIDGE:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT_PORT:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_SWITCH_UPSTREAM_PORT:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_SWITCH_DOWNSTREAM_PORT:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_EXPANDER_BUS:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_EXPANDER_BUS:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT:
+        if (pciopts->targetIndex != -1) {
+            virReportControllerInvalidOption(cont, model, modelName, "targetIndex");
+            return -1;
+        }
+        break;
+
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_DEFAULT:
+    case VIR_DOMAIN_CONTROLLER_MODEL_PCI_LAST:
+    default:
+        virReportEnumRangeError(virDomainControllerModelPCI, cont->model);
+        return -1;
+    }
+
     return qemuDomainDeviceDefValidateControllerPCIOld(cont, def, qemuCaps);
 }