Recreate the USB address cache at reconnect

When starting a new domain, we allocate the USB addresses and keep
an address cache in the domain object's private data.

However this data is lost on libvirtd restart.

Also generate the address cache if all the addresses have been
specified, so that devices hotplugged after libvirtd restart
also get theirs assigned.

https://bugzilla.redhat.com/show_bug.cgi?id=1387666

src/conf/domain_addr.c

@@ -1830,6 +1830,18 @@ virDomainUSBAddressAssign(virDomainUSBAddressSetPtr addrs,
 }
 
 
+int
+virDomainUSBAddressPresent(virDomainDeviceInfoPtr info,
+                           void *data ATTRIBUTE_UNUSED)
+{
+    if (info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_USB &&
+        virDomainUSBAddressPortIsValid(info->addr.usb.port))
+        return 0;
+
+    return -1;
+}
+
+
 int
 virDomainUSBAddressReserve(virDomainDeviceInfoPtr info,
                            void *data)

src/conf/domain_addr.h

@@ -300,6 +300,10 @@ size_t
 virDomainUSBAddressCountAllPorts(virDomainDefPtr def);
 void virDomainUSBAddressSetFree(virDomainUSBAddressSetPtr addrs);
 
+int
+virDomainUSBAddressPresent(virDomainDeviceInfoPtr info,
+                           void *data)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 int
 virDomainUSBAddressReserve(virDomainDeviceInfoPtr info,
                            void *data)

src/libvirt_private.syms

@@ -116,6 +116,7 @@ virDomainUSBAddressEnsure;
 virDomainUSBAddressPortFormat;
 virDomainUSBAddressPortFormatBuf;
 virDomainUSBAddressPortIsValid;
+virDomainUSBAddressPresent;
 virDomainUSBAddressRelease;
 virDomainUSBAddressReserve;
 virDomainUSBAddressSetAddControllers;

src/qemu/qemu_domain_address.c

@@ -1750,12 +1750,24 @@ qemuDomainUSBAddressAddHubs(virDomainDefPtr def)
 
 static int
 qemuDomainAssignUSBAddresses(virDomainDefPtr def,
-                             virDomainObjPtr obj)
+                             virDomainObjPtr obj,
+                             bool newDomain)
 {
     int ret = -1;
     virDomainUSBAddressSetPtr addrs = NULL;
     qemuDomainObjPrivatePtr priv = NULL;
 
+    if (!newDomain) {
+        /* only create the address cache for:
+         *  new domains
+         *  domains that already have all the addresses specified
+         * otherwise libvirt's attempt to recreate the USB topology via
+         * QEMU command line might fail */
+        if (virDomainUSBDeviceDefForeach(def, virDomainUSBAddressPresent, NULL,
+                                         false) < 0)
+            return 0;
+    }
+
     if (!(addrs = virDomainUSBAddressSetCreate()))
         goto cleanup;
 
@@ -1812,7 +1824,7 @@ qemuDomainAssignAddresses(virDomainDefPtr def,
     if (qemuDomainAssignPCIAddresses(def, qemuCaps, obj) < 0)
         return -1;
 
-    if (newDomain && qemuDomainAssignUSBAddresses(def, obj) < 0)
+    if (qemuDomainAssignUSBAddresses(def, obj, newDomain) < 0)
         return -1;
 
     return 0;