qemu: prefer 00:1D.x and 00:1A.x for USB2 controllers on Q35

The real Q35 machine puts the first USB controller set (EHCI+(UHCIx4))
on bus 0 slot 0x1D, and the 2nd USB controller set on bus 0 slot 0x1A,
so let's attempt to make the virtual machine match that for
controllers with auto-assigned addresses when possible.

Three test cases were added to assure that the proper addresses are
assigned - one with a single set of unaddressed USB controllers, one
with 3 (to grab both preferred slots plus one more), and one with the
order of the controller definitions reordered, to assure that the
auto-assignment isn't mixed up by order.

src/qemu/qemu_command.c

@@ -2068,6 +2068,47 @@ qemuDomainValidateDevicePCISlotsQ35(virDomainDefPtr def,
             }
             break;
 
+        case VIR_DOMAIN_CONTROLLER_TYPE_USB:
+            if ((def->controllers[i]->model
+                 == VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_UHCI1) &&
+                (def->controllers[i]->info.type
+                 == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE)) {
+                /* Try to assign the first found USB2 controller to
+                 * 00:1D.0 and 2nd to 00:1A.0 (because that is their
+                 * standard location on real Q35 hardware) unless they
+                 * are already taken, but don't insist on it.
+                 *
+                 * (NB: all other controllers at the same index will
+                 * get assigned to the same slot as the UHCI1 when
+                 * addresses are later assigned to all devices.)
+                 */
+                bool assign = false;
+
+                memset(&tmp_addr, 0, sizeof(tmp_addr));
+                tmp_addr.slot = 0x1D;
+                if (!virDomainPCIAddressSlotInUse(addrs, &tmp_addr)) {
+                    assign = true;
+                } else {
+                    tmp_addr.slot = 0x1A;
+                    if (!virDomainPCIAddressSlotInUse(addrs, &tmp_addr))
+                        assign = true;
+                }
+                if (assign) {
+                    if (virDomainPCIAddressReserveAddr(addrs, &tmp_addr,
+                                                       flags, false, true) < 0)
+                        goto cleanup;
+                    def->controllers[i]->info.type
+                        = VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI;
+                    def->controllers[i]->info.addr.pci.domain = 0;
+                    def->controllers[i]->info.addr.pci.bus = 0;
+                    def->controllers[i]->info.addr.pci.slot = tmp_addr.slot;
+                    def->controllers[i]->info.addr.pci.function = 0;
+                    def->controllers[i]->info.addr.pci.multi
+                       = VIR_TRISTATE_SWITCH_ON;
+                }
+            }
+            break;
+
         case VIR_DOMAIN_CONTROLLER_TYPE_PCI:
             if (def->controllers[i]->model == VIR_DOMAIN_CONTROLLER_MODEL_DMI_TO_PCI_BRIDGE &&
                 def->controllers[i]->info.type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE) {
@@ -2541,9 +2582,11 @@ qemuAssignDevicePCISlots(virDomainDefPtr def,
             bool foundAddr = false;
 
             memset(&tmp_addr, 0, sizeof(tmp_addr));
-            for (j = 0; j < i; j++) {
+            for (j = 0; j < def->ncontrollers; j++) {
                 if (IS_USB2_CONTROLLER(def->controllers[j]) &&
-                    def->controllers[j]->idx == def->controllers[i]->idx) {
+                    def->controllers[j]->idx == def->controllers[i]->idx &&
+                    def->controllers[j]->info.type
+                    == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI) {
                     addr = def->controllers[j]->info.addr.pci;
                     foundAddr = true;
                     break;
@@ -2553,6 +2596,7 @@ qemuAssignDevicePCISlots(virDomainDefPtr def,
             switch (def->controllers[i]->model) {
             case VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_EHCI1:
                 addr.function = 7;
+                addr.multi = VIR_TRISTATE_SWITCH_ABSENT;
                 break;
             case VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_UHCI1:
                 addr.function = 0;
@@ -2560,9 +2604,11 @@ qemuAssignDevicePCISlots(virDomainDefPtr def,
                 break;
             case VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_UHCI2:
                 addr.function = 1;
+                addr.multi = VIR_TRISTATE_SWITCH_ABSENT;
                 break;
             case VIR_DOMAIN_CONTROLLER_MODEL_USB_ICH9_UHCI3:
                 addr.function = 2;
+                addr.multi = VIR_TRISTATE_SWITCH_ABSENT;
                 break;
             }
 
@@ -2581,7 +2627,7 @@ qemuAssignDevicePCISlots(virDomainDefPtr def,
             }
             /* Finally we can reserve the slot+function */
             if (virDomainPCIAddressReserveAddr(addrs, &addr, flags,
-                                               false, false) < 0)
+                                               false, foundAddr) < 0)
                 goto error;
 
             def->controllers[i]->info.type = VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI;

tests/qemuxml2argvdata/qemuxml2argv-q35-usb2-multi.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/libexec/qemu-kvm \
+-name q35-test \
+-S \
+-M q35 \
+-m 2048 \
+-smp 2 \
+-uuid 11dbdcdd-4c3b-482b-8903-9bdb8c0a2774 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi \
+-boot c \
+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
+-device pci-bridge,chassis_nr=56,id=pci.2,bus=pci.1,addr=0x1 \
+-device ich9-usb-ehci1,id=usb,bus=pcie.0,addr=0x1d.0x7 \
+-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pcie.0,multifunction=on,\
+addr=0x1d \
+-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pcie.0,addr=0x1d.0x1 \
+-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pcie.0,addr=0x1d.0x2 \
+-device ich9-usb-ehci1,id=usb1,bus=pcie.0,addr=0x1a.0x7 \
+-device ich9-usb-uhci1,masterbus=usb1.0,firstport=0,bus=pcie.0,multifunction=on,\
+addr=0x1a \
+-device ich9-usb-uhci2,masterbus=usb1.0,firstport=2,bus=pcie.0,addr=0x1a.0x1 \
+-device ich9-usb-uhci3,masterbus=usb1.0,firstport=4,bus=pcie.0,addr=0x1a.0x2 \
+-device ich9-usb-ehci1,id=usb2,bus=pci.2,addr=0x1.0x7 \
+-device ich9-usb-uhci1,masterbus=usb2.0,firstport=0,bus=pci.2,multifunction=on,\
+addr=0x1 \
+-device ich9-usb-uhci2,masterbus=usb2.0,firstport=2,bus=pci.2,addr=0x1.0x1 \
+-device ich9-usb-uhci3,masterbus=usb2.0,firstport=4,bus=pci.2,addr=0x1.0x2 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-sata0-0-0 \
+-device ide-drive,bus=ide.0,drive=drive-sata0-0-0,id=sata0-0-0 \
+-vga qxl \
+-global qxl-vga.ram_size=67108864 \
+-global qxl-vga.vram_size=33554432

tests/qemuxml2argvdata/qemuxml2argv-q35-usb2-multi.xml

+<domain type='qemu'>
+  <name>q35-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'/>
+    <controller type='usb' index='0' model='ich9-uhci1'/>
+    <controller type='usb' index='0' model='ich9-uhci2'/>
+    <controller type='usb' index='0' model='ich9-uhci3'/>
+    <controller type='usb' index='1' model='ich9-ehci1'/>
+    <controller type='usb' index='1' model='ich9-uhci1'/>
+    <controller type='usb' index='1' model='ich9-uhci2'/>
+    <controller type='usb' index='1' model='ich9-uhci3'/>
+    <controller type='usb' index='2' model='ich9-ehci1'/>
+    <controller type='usb' index='2' model='ich9-uhci1'/>
+    <controller type='usb' index='2' model='ich9-uhci2'/>
+    <controller type='usb' index='2' model='ich9-uhci3'/>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' vgamem='8192' heads='1'/>
+    </video>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-q35-usb2-reorder.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/libexec/qemu-kvm \
+-name q35-test \
+-S \
+-M q35 \
+-m 2048 \
+-smp 2 \
+-uuid 11dbdcdd-4c3b-482b-8903-9bdb8c0a2774 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi \
+-boot c \
+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
+-device pci-bridge,chassis_nr=56,id=pci.2,bus=pci.1,addr=0x1 \
+-device ich9-usb-ehci1,id=usb,bus=pcie.0,addr=0x1d.0x7 \
+-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pcie.0,multifunction=on,\
+addr=0x1d \
+-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pcie.0,addr=0x1d.0x1 \
+-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pcie.0,addr=0x1d.0x2 \
+-device ich9-usb-ehci1,id=usb1,bus=pcie.0,addr=0x1a.0x7 \
+-device ich9-usb-uhci1,masterbus=usb1.0,firstport=0,bus=pcie.0,multifunction=on,\
+addr=0x1a \
+-device ich9-usb-uhci3,masterbus=usb1.0,firstport=4,bus=pcie.0,addr=0x1a.0x2 \
+-device ich9-usb-uhci2,masterbus=usb1.0,firstport=2,bus=pcie.0,addr=0x1a.0x1 \
+-device ich9-usb-ehci1,id=usb2,bus=pci.2,addr=0x1.0x7 \
+-device ich9-usb-uhci3,masterbus=usb2.0,firstport=4,bus=pci.2,addr=0x1.0x2 \
+-device ich9-usb-uhci2,masterbus=usb2.0,firstport=2,bus=pci.2,addr=0x1.0x1 \
+-device ich9-usb-uhci1,masterbus=usb2.0,firstport=0,bus=pci.2,multifunction=on,\
+addr=0x1 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-sata0-0-0 \
+-device ide-drive,bus=ide.0,drive=drive-sata0-0-0,id=sata0-0-0 \
+-vga qxl \
+-global qxl-vga.ram_size=67108864 \
+-global qxl-vga.vram_size=33554432

tests/qemuxml2argvdata/qemuxml2argv-q35-usb2-reorder.xml

+<domain type='qemu'>
+  <name>q35-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci1'/>
+    <controller type='usb' index='0' model='ich9-uhci2'/>
+    <controller type='usb' index='0' model='ich9-uhci3'/>
+    <controller type='usb' index='1' model='ich9-uhci1'/>
+    <controller type='usb' index='2' model='ich9-uhci3'/>
+    <controller type='usb' index='0' model='ich9-ehci1'/>
+    <controller type='usb' index='2' model='ich9-ehci1'/>
+    <controller type='usb' index='1' model='ich9-uhci3'/>
+    <controller type='usb' index='1' model='ich9-uhci2'/>
+    <controller type='usb' index='1' model='ich9-ehci1'/>
+    <controller type='usb' index='2' model='ich9-uhci2'/>
+    <controller type='usb' index='2' model='ich9-uhci1'/>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' vgamem='8192' heads='1'/>
+    </video>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-q35-usb2.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/libexec/qemu-kvm \
+-name q35-test \
+-S \
+-M q35 \
+-m 2048 \
+-smp 2 \
+-uuid 11dbdcdd-4c3b-482b-8903-9bdb8c0a2774 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi \
+-boot c \
+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
+-device pci-bridge,chassis_nr=56,id=pci.2,bus=pci.1,addr=0x1 \
+-device ich9-usb-ehci1,id=usb,bus=pcie.0,addr=0x1d.0x7 \
+-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pcie.0,multifunction=on,\
+addr=0x1d \
+-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pcie.0,addr=0x1d.0x1 \
+-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pcie.0,addr=0x1d.0x2 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-sata0-0-0 \
+-device ide-drive,bus=ide.0,drive=drive-sata0-0-0,id=sata0-0-0 \
+-vga qxl \
+-global qxl-vga.ram_size=67108864 \
+-global qxl-vga.vram_size=33554432

tests/qemuxml2argvdata/qemuxml2argv-q35-usb2.xml

+<domain type='qemu'>
+  <name>q35-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'/>
+    <controller type='usb' index='0' model='ich9-uhci1'/>
+    <controller type='usb' index='0' model='ich9-uhci2'/>
+    <controller type='usb' index='0' model='ich9-uhci3'/>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' vgamem='8192' heads='1'/>
+    </video>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1515,6 +1515,27 @@ mymain(void)
             QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_PCI_BRIDGE,
             QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE, QEMU_CAPS_ICH9_AHCI,
             QEMU_CAPS_PIIX_DISABLE_S3, QEMU_CAPS_PIIX_DISABLE_S4);
+    DO_TEST("q35-usb2",
+            QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
+            QEMU_CAPS_VGA_QXL, QEMU_CAPS_DEVICE_QXL);
+    DO_TEST("q35-usb2-multi",
+            QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
+            QEMU_CAPS_VGA_QXL, QEMU_CAPS_DEVICE_QXL);
+    DO_TEST("q35-usb2-reorder",
+            QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
+            QEMU_CAPS_VGA_QXL, QEMU_CAPS_DEVICE_QXL);
     DO_TEST("pcie-root-port",
             QEMU_CAPS_DEVICE, QEMU_CAPS_DEVICE_PCI_BRIDGE,
             QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,

tests/qemuxml2xmloutdata/qemuxml2xmlout-q35-usb2-multi.xml

+<domain type='qemu'>
+  <name>q35-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'/>
+    <controller type='usb' index='0' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='usb' index='1' model='ich9-ehci1'/>
+    <controller type='usb' index='1' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='usb' index='1' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='1' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='usb' index='2' model='ich9-ehci1'/>
+    <controller type='usb' index='2' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='usb' index='2' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='2' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='sata' index='0'/>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' vgamem='8192' heads='1'/>
+    </video>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/qemuxml2xmlout-q35-usb2-reorder.xml

+<domain type='qemu'>
+  <name>q35-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'/>
+    <controller type='usb' index='0' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='usb' index='1' model='ich9-ehci1'/>
+    <controller type='usb' index='1' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='usb' index='1' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='usb' index='1' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='2' model='ich9-ehci1'/>
+    <controller type='usb' index='2' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='usb' index='2' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='2' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='sata' index='0'/>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' vgamem='8192' heads='1'/>
+    </video>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/qemuxml2xmlout-q35-usb2.xml

+<domain type='qemu'>
+  <name>q35-test</name>
+  <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid>
+  <memory unit='KiB'>2097152</memory>
+  <currentMemory unit='KiB'>2097152</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='sda' bus='sata'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='56'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'/>
+    <controller type='usb' index='0' model='ich9-uhci1'>
+      <master startport='0'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci2'>
+      <master startport='2'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci3'>
+      <master startport='4'/>
+    </controller>
+    <controller type='sata' index='0'/>
+    <video>
+      <model type='qxl' ram='65536' vram='32768' vgamem='8192' heads='1'/>
+    </video>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -518,6 +518,9 @@ mymain(void)
     DO_TEST_DIFFERENT("pci-autoadd-idx");
     DO_TEST_DIFFERENT("pcie-root");
     DO_TEST_DIFFERENT("q35");
+    DO_TEST_DIFFERENT("q35-usb2");
+    DO_TEST_DIFFERENT("q35-usb2-multi");
+    DO_TEST_DIFFERENT("q35-usb2-reorder");
     DO_TEST("pcie-root-port");
     DO_TEST("pcie-root-port-too-many");
     DO_TEST("pcie-switch-upstream-port");