qemu: Add enough USB hubs to accomodate all devices

Commit 815d98a started auto-adding one hub if there are more USB devices
than available USB ports.

This was a strange choice, since there might be even more devices.
Before USB address allocation was implemented in libvirt, QEMU
automatically added a new USB hub if the old one was full.

Adjust the logic to try adding as many hubs as will be needed
to plug in all the specified devices.

https://bugzilla.redhat.com/show_bug.cgi?id=1410188

src/qemu/qemu_domain_address.c

@@ -2300,19 +2300,24 @@ qemuDomainUSBAddressAddHubs(virDomainDefPtr def)
     struct qemuAssignUSBIteratorInfo data = { .count = 0 };
     virDomainHubDefPtr hub = NULL;
     size_t available_ports;
+    size_t hubs_needed = 0;
     int ret = -1;
+    size_t i;
 
     available_ports = virDomainUSBAddressCountAllPorts(def);
     ignore_value(virDomainUSBDeviceDefForeach(def,
                                               qemuDomainAssignUSBPortsCounter,
                                               &data,
                                               false));
-    VIR_DEBUG("Found %zu USB devices and %zu provided USB ports",
-              data.count, available_ports);
 
-    /* Add one hub if there are more devices than ports
-     * otherwise it's up to the user to specify more hubs/controllers */
-    if (data.count > available_ports) {
+    if (data.count > available_ports)
+        hubs_needed = VIR_DIV_UP(data.count - available_ports + 1,
+                                 VIR_DOMAIN_USB_HUB_PORTS - 1);
+
+    VIR_DEBUG("Found %zu USB devices and %zu provided USB ports; adding %zu hubs",
+              data.count, available_ports, hubs_needed);
+
+    for (i = 0; i < hubs_needed; i++) {
         if (VIR_ALLOC(hub) < 0)
             return -1;
         hub->type = VIR_DOMAIN_HUB_TYPE_USB;

tests/qemuxml2argvdata/qemuxml2argv-usb-hub-autoadd-deluxe.args

@@ -0,0 +1,42 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu \
+-name QEMUGuest1 \
+-S \
+-M pc \
+-m 214 \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-nographic \
+-nodefconfig \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=readline \
+-no-acpi \
+-boot c \
+-usb \
+-device usb-hub,id=hub0,bus=usb.0,port=1 \
+-device usb-hub,id=hub1,bus=usb.0,port=2 \
+-device usb-hub,id=hub2,bus=usb.0,port=1.1 \
+-device usb-mouse,id=input0,bus=usb.0,port=1.2 \
+-device usb-mouse,id=input1,bus=usb.0,port=1.3 \
+-device usb-mouse,id=input2,bus=usb.0,port=1.4 \
+-device usb-tablet,id=input3,bus=usb.0,port=1.5 \
+-device usb-tablet,id=input4,bus=usb.0,port=1.6 \
+-device usb-tablet,id=input5,bus=usb.0,port=1.7 \
+-device usb-tablet,id=input6,bus=usb.0,port=1.8 \
+-device usb-tablet,id=input7,bus=usb.0,port=1.1.1 \
+-device usb-tablet,id=input8,bus=usb.0,port=1.1.2 \
+-device usb-tablet,id=input9,bus=usb.0,port=1.1.3 \
+-device usb-tablet,id=input10,bus=usb.0,port=1.1.4 \
+-device usb-tablet,id=input11,bus=usb.0,port=1.1.5 \
+-device usb-tablet,id=input12,bus=usb.0,port=1.1.6 \
+-device usb-tablet,id=input13,bus=usb.0,port=1.1.7 \
+-device usb-tablet,id=input14,bus=usb.0,port=1.1.8 \
+-device usb-tablet,id=input15,bus=usb.0,port=2.1 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/qemuxml2argv-usb-hub-autoadd-deluxe.xml

@@ -0,0 +1,35 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <controller type='usb' index='0'/>
+    <memballoon model='virtio'/>
+    <input type='mouse' bus='usb'>
+    </input>
+    <input type='mouse' bus='usb'>
+    </input>
+    <input type='mouse' bus='usb'>
+    </input>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+    <input type='tablet' bus='usb'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1332,6 +1332,9 @@ mymain(void)
     DO_TEST("usb-hub-autoadd",
             QEMU_CAPS_CHARDEV, QEMU_CAPS_USB_HUB,
             QEMU_CAPS_NODEFCONFIG);
+    DO_TEST("usb-hub-autoadd-deluxe",
+            QEMU_CAPS_CHARDEV, QEMU_CAPS_USB_HUB,
+            QEMU_CAPS_NODEFCONFIG);
     DO_TEST_PARSE_ERROR("usb-hub-conflict",
             QEMU_CAPS_CHARDEV, QEMU_CAPS_USB_HUB,
             QEMU_CAPS_NODEFCONFIG);