qemu: assign virtio devices to PCIe slot when appropriate

libvirt previously assigned nearly all devices to a "hotpluggable"
legacy PCI slot even on machines with a PCIe root bus (and even though
most such machines don't even support hotplug on legacy PCI slots!)
Forcing all devices onto legacy PCI slots means that the domain will
need a dmi-to-pci-bridge (to convert from PCIe to legacy PCI) and a
pci-bridge (to provide hotpluggable legacy PCI slots which, again,
usually aren't hotpluggable anyway).

To help reduce the need for these legacy controllers, this patch tries
to assign virtio-1.0-capable devices to PCIe slots whenever possible,
by setting appropriate connectFlags in
virDomainCalculateDevicePCIConnectFlags(). Happily, when that function
was written (just a few commits ago) it was created with a
"virtioFlags" argument, set by both of its callers, which is the
proper connectFlags to set for any virtio-*-pci device - depending on
the arch/machinetype of the domain, and whether or not the qemu binary
supports virtio-1.0, that flag will have either been set to PCI or
PCIe. This patch merely enables the functionality by setting the flags
for the device to whatever is in virtioFlags if the device is a
virtio-*-pci device.

NB: the first virtio video device will be placed directly on bus 0
slot 1 rather than on a pcie-root-port due to the override for primary
video devices in qemuDomainValidateDevicePCISlotsQ35(). Whether or not
to change that is a topic of discussion, but this patch doesn't change
that particular behavior.

NB2: since the slot must be hotpluggable, and pcie-root (the PCIe root
complex) does *not* support hotplug, this means that suitable
controllers must also be in the config (i.e. either pcie-root-port, or
pcie-downstream-port). For now, libvirt doesn't add those
automatically, so if you put virtio devices in a config for a qemu
that has PCIe-capable virtio devices, you'll need to add extra
pcie-root-ports yourself. That requirement will be eliminated in a
future patch, but for now, it's simple to do this:

   <controller type='pci' model='pcie-root-port'/>
   <controller type='pci' model='pcie-root-port'/>
   <controller type='pci' model='pcie-root-port'/>
   ...

Partially Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1330024

src/qemu/qemu_domain_address.c

@@ -430,8 +430,7 @@ static virDomainPCIConnectFlags
 qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
                                          virDomainPCIConnectFlags pcieFlags
                                          ATTRIBUTE_UNUSED,
-                                         virDomainPCIConnectFlags virtioFlags
-                                         ATTRIBUTE_UNUSED)
+                                         virDomainPCIConnectFlags virtioFlags)
 {
     virDomainPCIConnectFlags pciFlags = (VIR_PCI_CONNECT_TYPE_PCI_DEVICE |
                                          VIR_PCI_CONNECT_HOTPLUGGABLE);
@@ -471,10 +470,29 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
             }
 
         case VIR_DOMAIN_CONTROLLER_TYPE_IDE:
+            return pciFlags;
+
         case VIR_DOMAIN_CONTROLLER_TYPE_SCSI:
-        case VIR_DOMAIN_CONTROLLER_TYPE_VIRTIO_SERIAL:
+            switch ((virDomainControllerModelSCSI) cont->model) {
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_SCSI:
+                return virtioFlags;
+
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_AUTO:
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_BUSLOGIC:
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LSILOGIC:
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LSISAS1068:
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VMPVSCSI:
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_IBMVSCSI:
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LSISAS1078:
                 return pciFlags;
 
+            case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LAST:
+                return 0;
+            }
+
+        case VIR_DOMAIN_CONTROLLER_TYPE_VIRTIO_SERIAL:
+            return virtioFlags;
+
         case VIR_DOMAIN_CONTROLLER_TYPE_FDC:
         case VIR_DOMAIN_CONTROLLER_TYPE_CCID:
         case VIR_DOMAIN_CONTROLLER_TYPE_LAST:
@@ -485,7 +503,7 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
 
     case VIR_DOMAIN_DEVICE_FS:
         /* the only type of filesystem so far is virtio-9p-pci */
-        return pciFlags;
+        return virtioFlags;
 
     case VIR_DOMAIN_DEVICE_NET: {
         virDomainNetDefPtr net = dev->data.net;
@@ -498,6 +516,10 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
             STREQ(net->model, "usb-net")) {
             return 0;
         }
+
+        if (STREQ(net->model, "virtio"))
+            return  virtioFlags;
+
         return pciFlags;
     }
 
@@ -519,7 +541,7 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
     case VIR_DOMAIN_DEVICE_DISK:
         switch ((virDomainDiskBus) dev->data.disk->bus) {
         case VIR_DOMAIN_DISK_BUS_VIRTIO:
-            return pciFlags; /* only virtio disks use PCI */
+            return virtioFlags; /* only virtio disks use PCI */
 
         case VIR_DOMAIN_DISK_BUS_IDE:
         case VIR_DOMAIN_DISK_BUS_FDC:
@@ -539,7 +561,7 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
     case VIR_DOMAIN_DEVICE_MEMBALLOON:
         switch ((virDomainMemballoonModel) dev->data.memballoon->model) {
         case VIR_DOMAIN_MEMBALLOON_MODEL_VIRTIO:
-            return pciFlags;
+            return virtioFlags;
 
         case VIR_DOMAIN_MEMBALLOON_MODEL_XEN:
         case VIR_DOMAIN_MEMBALLOON_MODEL_NONE:
@@ -550,7 +572,7 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
     case VIR_DOMAIN_DEVICE_RNG:
         switch ((virDomainRNGModel) dev->data.rng->model) {
         case VIR_DOMAIN_RNG_MODEL_VIRTIO:
-            return pciFlags;
+            return virtioFlags;
 
         case VIR_DOMAIN_RNG_MODEL_LAST:
             return 0;
@@ -571,6 +593,8 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
     case VIR_DOMAIN_DEVICE_VIDEO:
         switch ((virDomainVideoType) dev->data.video->type) {
         case VIR_DOMAIN_VIDEO_TYPE_VIRTIO:
+            return virtioFlags;
+
         case VIR_DOMAIN_VIDEO_TYPE_VGA:
         case VIR_DOMAIN_VIDEO_TYPE_CIRRUS:
         case VIR_DOMAIN_VIDEO_TYPE_VMVGA:
@@ -590,7 +614,7 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
     case VIR_DOMAIN_DEVICE_INPUT:
         switch ((virDomainInputBus) dev->data.input->bus) {
         case VIR_DOMAIN_INPUT_BUS_VIRTIO:
-            return pciFlags;
+            return virtioFlags;
 
         case VIR_DOMAIN_INPUT_BUS_PS2:
         case VIR_DOMAIN_INPUT_BUS_USB:

tests/qemuxml2argvdata/qemuxml2argv-q35-pcie.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,sockets=2,cores=1,threads=1 \
+-uuid 11dbdcdd-4c3b-482b-8903-9bdb8c0a2774 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/lib/domain--1-q35-test/monitor.sock,server,nowait \
+-no-acpi \
+-boot c \
+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
+-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
+-device ioh3420,port=0x10,chassis=3,id=pci.3,bus=pcie.0,addr=0x2 \
+-device ioh3420,port=0x18,chassis=4,id=pci.4,bus=pcie.0,addr=0x3 \
+-device ioh3420,port=0x20,chassis=5,id=pci.5,bus=pcie.0,addr=0x4 \
+-device ioh3420,port=0x28,chassis=6,id=pci.6,bus=pcie.0,addr=0x5 \
+-device ioh3420,port=0x30,chassis=7,id=pci.7,bus=pcie.0,addr=0x6 \
+-device ioh3420,port=0x38,chassis=8,id=pci.8,bus=pcie.0,addr=0x7 \
+-device ioh3420,port=0x40,chassis=9,id=pci.9,bus=pcie.0,addr=0x8 \
+-device ioh3420,port=0x48,chassis=10,id=pci.10,bus=pcie.0,addr=0x9 \
+-device ioh3420,port=0x50,chassis=11,id=pci.11,bus=pcie.0,addr=0xa \
+-device ioh3420,port=0x58,chassis=12,id=pci.12,bus=pcie.0,addr=0xb \
+-device ioh3420,port=0x60,chassis=13,id=pci.13,bus=pcie.0,addr=0xc \
+-device ioh3420,port=0x68,chassis=14,id=pci.14,bus=pcie.0,addr=0xd \
+-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 virtio-scsi-pci,id=scsi0,bus=pci.6,addr=0x0 \
+-device virtio-serial-pci,id=virtio-serial0,bus=pci.5,addr=0x0 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-virtio-disk1 \
+-device virtio-blk-pci,bus=pci.7,addr=0x0,drive=drive-virtio-disk1,\
+id=virtio-disk1 \
+-fsdev local,security_model=passthrough,id=fsdev-fs0,path=/export/to/guest \
+-device virtio-9p-pci,id=fs0,fsdev=fsdev-fs0,mount_tag=/import/from/host,\
+bus=pci.3,addr=0x0 \
+-netdev user,id=hostnet0 \
+-device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:11:22:33:44:55,bus=pci.4,\
+addr=0x0 \
+-device virtio-input-host-pci,id=input0,evdev=/dev/input/event1234,bus=pci.10,\
+addr=0x0 \
+-device virtio-mouse-pci,id=input1,bus=pci.11,addr=0x0 \
+-device virtio-keyboard-pci,id=input2,bus=pci.12,addr=0x0 \
+-device virtio-tablet-pci,id=input3,bus=pci.13,addr=0x0 \
+-device virtio-gpu-pci,id=video0,bus=pcie.0,addr=0x1 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.8,addr=0x0 \
+-object rng-random,id=objrng0,filename=/dev/urandom \
+-device virtio-rng-pci,rng=objrng0,id=rng0,max-bytes=123,period=1234,bus=pci.9,\
+addr=0x0

tests/qemuxml2argvdata/qemuxml2argv-q35-pcie.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>
+    <controller type='pci' model='pcie-root'/>
+    <controller type='pci' model='dmi-to-pci-bridge'/>
+    <controller type='pci' model='pci-bridge'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='pci' model='pcie-root-port'/>
+    <controller type='virtio-serial'/>
+    <controller type='scsi' model='virtio-scsi'/>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='vdb' bus='virtio'/>
+    </disk>
+    <filesystem type='mount'>
+      <source dir='/export/to/guest'/>
+      <target dir='/import/from/host'/>
+    </filesystem>
+    <video>
+      <model type='virtio'/>
+    </video>
+    <interface type='user'>
+      <mac address='00:11:22:33:44:55'/>
+      <model type='virtio'/>
+    </interface>
+    <memballoon model='virtio'/>
+    <rng model='virtio'>
+      <rate bytes='123' period='1234'/>
+      <backend model='random'>/dev/urandom</backend>
+    </rng>
+    <input type='passthrough' bus='virtio'>
+      <source evdev='/dev/input/event1234'/>
+    </input>
+    <input type='mouse' bus='virtio'/>
+    <input type='keyboard' bus='virtio'/>
+    <input type='tablet' bus='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pci.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,sockets=2,cores=1,threads=1 \
+-uuid 11dbdcdd-4c3b-482b-8903-9bdb8c0a2774 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/lib/domain--1-q35-test/monitor.sock,server,nowait \
+-no-acpi \
+-boot c \
+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
+-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
+-device ioh3420,port=0x10,chassis=3,id=pci.3,bus=pcie.0,addr=0x2 \
+-device ioh3420,port=0x18,chassis=4,id=pci.4,bus=pcie.0,addr=0x3 \
+-device ioh3420,port=0x20,chassis=5,id=pci.5,bus=pcie.0,addr=0x4 \
+-device ioh3420,port=0x28,chassis=6,id=pci.6,bus=pcie.0,addr=0x5 \
+-device ioh3420,port=0x30,chassis=7,id=pci.7,bus=pcie.0,addr=0x6 \
+-device ioh3420,port=0x38,chassis=8,id=pci.8,bus=pcie.0,addr=0x7 \
+-device ioh3420,port=0x40,chassis=9,id=pci.9,bus=pcie.0,addr=0x8 \
+-device ioh3420,port=0x48,chassis=10,id=pci.10,bus=pcie.0,addr=0x9 \
+-device ioh3420,port=0x50,chassis=11,id=pci.11,bus=pcie.0,addr=0xa \
+-device ioh3420,port=0x58,chassis=12,id=pci.12,bus=pcie.0,addr=0xb \
+-device ioh3420,port=0x60,chassis=13,id=pci.13,bus=pcie.0,addr=0xc \
+-device ioh3420,port=0x68,chassis=14,id=pci.14,bus=pcie.0,addr=0xd \
+-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 virtio-scsi-pci,id=scsi0,bus=pci.2,addr=0x4 \
+-device virtio-serial-pci,id=virtio-serial0,bus=pci.2,addr=0x3 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-virtio-disk1 \
+-device virtio-blk-pci,bus=pci.2,addr=0x5,drive=drive-virtio-disk1,\
+id=virtio-disk1 \
+-fsdev local,security_model=passthrough,id=fsdev-fs0,path=/export/to/guest \
+-device virtio-9p-pci,id=fs0,fsdev=fsdev-fs0,mount_tag=/import/from/host,\
+bus=pci.2,addr=0x1 \
+-netdev user,id=hostnet0 \
+-device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:11:22:33:44:55,bus=pci.2,\
+addr=0x2 \
+-device virtio-input-host-pci,id=input0,evdev=/dev/input/event1234,bus=pci.2,\
+addr=0x8 \
+-device virtio-mouse-pci,id=input1,bus=pci.2,addr=0x9 \
+-device virtio-keyboard-pci,id=input2,bus=pci.2,addr=0xa \
+-device virtio-tablet-pci,id=input3,bus=pci.2,addr=0xb \
+-device virtio-gpu-pci,id=video0,bus=pcie.0,addr=0x1 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.2,addr=0x6 \
+-object rng-random,id=objrng0,filename=/dev/urandom \
+-device virtio-rng-pci,rng=objrng0,id=rng0,max-bytes=123,period=1234,bus=pci.2,\
+addr=0x7

tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pci.xml

+qemuxml2argv-q35-pcie.xml
\ No newline at end of file

tests/qemuxml2argvtest.c

@@ -1770,6 +1770,54 @@ mymain(void)
             QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_ICH9_USB_EHCI1,
             QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
             QEMU_CAPS_DEVICE_QXL);
+    /* verify that devices with pcie capability are assigned to a pcie slot */
+    DO_TEST("q35-pcie",
+            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY,
+            QEMU_CAPS_DEVICE_VIRTIO_RNG,
+            QEMU_CAPS_OBJECT_RNG_RANDOM,
+            QEMU_CAPS_NETDEV,
+            QEMU_CAPS_DEVICE_VIRTIO_NET,
+            QEMU_CAPS_DEVICE_VIRTIO_GPU,
+            QEMU_CAPS_VIRTIO_GPU_VIRGL,
+            QEMU_CAPS_VIRTIO_KEYBOARD,
+            QEMU_CAPS_VIRTIO_MOUSE,
+            QEMU_CAPS_VIRTIO_TABLET,
+            QEMU_CAPS_VIRTIO_INPUT_HOST,
+            QEMU_CAPS_VIRTIO_SCSI,
+            QEMU_CAPS_FSDEV,
+            QEMU_CAPS_FSDEV_WRITEOUT,
+            QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_IOH3420,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
+    /* same XML as q35-pcie, but don't set
+     * QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY, so virtio devices should
+     * be assigned to legacy pci slots
+     */
+    DO_TEST("q35-virtio-pci",
+            QEMU_CAPS_DEVICE_VIRTIO_RNG,
+            QEMU_CAPS_OBJECT_RNG_RANDOM,
+            QEMU_CAPS_NETDEV,
+            QEMU_CAPS_DEVICE_VIRTIO_NET,
+            QEMU_CAPS_DEVICE_VIRTIO_GPU,
+            QEMU_CAPS_VIRTIO_GPU_VIRGL,
+            QEMU_CAPS_VIRTIO_KEYBOARD,
+            QEMU_CAPS_VIRTIO_MOUSE,
+            QEMU_CAPS_VIRTIO_TABLET,
+            QEMU_CAPS_VIRTIO_INPUT_HOST,
+            QEMU_CAPS_VIRTIO_SCSI,
+            QEMU_CAPS_FSDEV,
+            QEMU_CAPS_FSDEV_WRITEOUT,
+            QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_IOH3420,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
     DO_TEST("pcie-root-port",
             QEMU_CAPS_DEVICE_PCI_BRIDGE,
             QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,

tests/qemuxml2xmloutdata/qemuxml2xmlout-q35-pcie.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='vdb' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='2'/>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
+    </controller>
+    <controller type='pci' index='3' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='3' port='0x10'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+    </controller>
+    <controller type='pci' index='4' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='4' port='0x18'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </controller>
+    <controller type='pci' index='5' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='5' port='0x20'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+    </controller>
+    <controller type='pci' index='6' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='6' port='0x28'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
+    </controller>
+    <controller type='pci' index='7' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='7' port='0x30'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
+    </controller>
+    <controller type='pci' index='8' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='8' port='0x38'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
+    </controller>
+    <controller type='pci' index='9' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='9' port='0x40'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
+    </controller>
+    <controller type='pci' index='10' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='10' port='0x48'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>
+    </controller>
+    <controller type='pci' index='11' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='11' port='0x50'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
+    </controller>
+    <controller type='pci' index='12' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='12' port='0x58'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/>
+    </controller>
+    <controller type='pci' index='13' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='13' port='0x60'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/>
+    </controller>
+    <controller type='pci' index='14' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='14' port='0x68'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0d' function='0x0'/>
+    </controller>
+    <controller type='virtio-serial' index='0'>
+      <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
+    </controller>
+    <controller type='scsi' index='0' model='virtio-scsi'>
+      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x7'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci1'>
+      <master startport='0'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0' multifunction='on'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci2'>
+      <master startport='2'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x1'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci3'>
+      <master startport='4'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x2'/>
+    </controller>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <filesystem type='mount' accessmode='passthrough'>
+      <source dir='/export/to/guest'/>
+      <target dir='/import/from/host'/>
+      <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
+    </filesystem>
+    <interface type='user'>
+      <mac address='00:11:22:33:44:55'/>
+      <model type='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
+    </interface>
+    <input type='passthrough' bus='virtio'>
+      <source evdev='/dev/input/event1234'/>
+      <address type='pci' domain='0x0000' bus='0x0a' slot='0x00' function='0x0'/>
+    </input>
+    <input type='mouse' bus='virtio'>
+      <address type='pci' domain='0x0000' bus='0x0b' slot='0x00' function='0x0'/>
+    </input>
+    <input type='keyboard' bus='virtio'>
+      <address type='pci' domain='0x0000' bus='0x0c' slot='0x00' function='0x0'/>
+    </input>
+    <input type='tablet' bus='virtio'>
+      <address type='pci' domain='0x0000' bus='0x0d' slot='0x00' function='0x0'/>
+    </input>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <video>
+      <model type='virtio' heads='1' primary='yes'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
+    </video>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x08' slot='0x00' function='0x0'/>
+    </memballoon>
+    <rng model='virtio'>
+      <rate bytes='123' period='1234'/>
+      <backend model='random'>/dev/urandom</backend>
+      <address type='pci' domain='0x0000' bus='0x09' slot='0x00' function='0x0'/>
+    </rng>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/qemuxml2xmlout-q35-virtio-pci.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='vdb' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x05' function='0x0'/>
+    </disk>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
+      <model name='i82801b11-bridge'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
+    </controller>
+    <controller type='pci' index='2' model='pci-bridge'>
+      <model name='pci-bridge'/>
+      <target chassisNr='2'/>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
+    </controller>
+    <controller type='pci' index='3' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='3' port='0x10'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+    </controller>
+    <controller type='pci' index='4' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='4' port='0x18'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </controller>
+    <controller type='pci' index='5' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='5' port='0x20'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+    </controller>
+    <controller type='pci' index='6' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='6' port='0x28'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
+    </controller>
+    <controller type='pci' index='7' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='7' port='0x30'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
+    </controller>
+    <controller type='pci' index='8' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='8' port='0x38'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
+    </controller>
+    <controller type='pci' index='9' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='9' port='0x40'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
+    </controller>
+    <controller type='pci' index='10' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='10' port='0x48'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>
+    </controller>
+    <controller type='pci' index='11' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='11' port='0x50'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
+    </controller>
+    <controller type='pci' index='12' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='12' port='0x58'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/>
+    </controller>
+    <controller type='pci' index='13' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='13' port='0x60'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/>
+    </controller>
+    <controller type='pci' index='14' model='pcie-root-port'>
+      <model name='ioh3420'/>
+      <target chassis='14' port='0x68'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x0d' function='0x0'/>
+    </controller>
+    <controller type='virtio-serial' index='0'>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0'/>
+    </controller>
+    <controller type='scsi' index='0' model='virtio-scsi'>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x04' function='0x0'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-ehci1'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x7'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci1'>
+      <master startport='0'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0' multifunction='on'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci2'>
+      <master startport='2'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x1'/>
+    </controller>
+    <controller type='usb' index='0' model='ich9-uhci3'>
+      <master startport='4'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x2'/>
+    </controller>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <filesystem type='mount' accessmode='passthrough'>
+      <source dir='/export/to/guest'/>
+      <target dir='/import/from/host'/>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
+    </filesystem>
+    <interface type='user'>
+      <mac address='00:11:22:33:44:55'/>
+      <model type='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x02' function='0x0'/>
+    </interface>
+    <input type='passthrough' bus='virtio'>
+      <source evdev='/dev/input/event1234'/>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x08' function='0x0'/>
+    </input>
+    <input type='mouse' bus='virtio'>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x09' function='0x0'/>
+    </input>
+    <input type='keyboard' bus='virtio'>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x0a' function='0x0'/>
+    </input>
+    <input type='tablet' bus='virtio'>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x0b' function='0x0'/>
+    </input>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <video>
+      <model type='virtio' heads='1' primary='yes'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
+    </video>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x06' function='0x0'/>
+    </memballoon>
+    <rng model='virtio'>
+      <rate bytes='123' period='1234'/>
+      <backend model='random'>/dev/urandom</backend>
+      <address type='pci' domain='0x0000' bus='0x02' slot='0x07' function='0x0'/>
+    </rng>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -696,6 +696,49 @@ mymain(void)
             QEMU_CAPS_ICH9_AHCI, QEMU_CAPS_PCI_MULTIFUNCTION,
             QEMU_CAPS_ICH9_USB_EHCI1, QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
             QEMU_CAPS_DEVICE_QXL);
+    DO_TEST("q35-pcie",
+            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY,
+            QEMU_CAPS_DEVICE_VIRTIO_RNG,
+            QEMU_CAPS_OBJECT_RNG_RANDOM,
+            QEMU_CAPS_DEVICE_VIRTIO_NET,
+            QEMU_CAPS_DEVICE_VIRTIO_GPU,
+            QEMU_CAPS_VIRTIO_GPU_VIRGL,
+            QEMU_CAPS_VIRTIO_KEYBOARD,
+            QEMU_CAPS_VIRTIO_MOUSE,
+            QEMU_CAPS_VIRTIO_TABLET,
+            QEMU_CAPS_VIRTIO_INPUT_HOST,
+            QEMU_CAPS_VIRTIO_SCSI,
+            QEMU_CAPS_FSDEV,
+            QEMU_CAPS_FSDEV_WRITEOUT,
+            QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_IOH3420,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
+    /* same XML as q35-pcie, but don't set
+       QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY */
+    DO_TEST("q35-virtio-pci",
+            QEMU_CAPS_DEVICE_VIRTIO_RNG,
+            QEMU_CAPS_OBJECT_RNG_RANDOM,
+            QEMU_CAPS_DEVICE_VIRTIO_NET,
+            QEMU_CAPS_DEVICE_VIRTIO_GPU,
+            QEMU_CAPS_VIRTIO_GPU_VIRGL,
+            QEMU_CAPS_VIRTIO_KEYBOARD,
+            QEMU_CAPS_VIRTIO_MOUSE,
+            QEMU_CAPS_VIRTIO_TABLET,
+            QEMU_CAPS_VIRTIO_INPUT_HOST,
+            QEMU_CAPS_VIRTIO_SCSI,
+            QEMU_CAPS_FSDEV,
+            QEMU_CAPS_FSDEV_WRITEOUT,
+            QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_IOH3420,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
 
     DO_TEST("pcie-root",
             QEMU_CAPS_DEVICE_PCI_BRIDGE, QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,