qemu_capabilities: Do not report USB as subsystem type if it is not available

libvirt currently always reports that USB is available as a bus subsystem
type when running "virsh domcapabilities". However, this is not always
true, for example the qemu-system-s390x binary normally never has support
for USB. Thus we should only report that USB is available if there is
also a USB host controller available where we can attach USB devices.
Reported-by: NSebastian Mitterle <smitterl@redhat.com>
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1759849Signed-off-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_capabilities.c

@@ -5674,10 +5674,21 @@ virQEMUCapsFillDomainDeviceHostdevCaps(virQEMUCapsPtr qemuCaps,
                              VIR_DOMAIN_STARTUP_POLICY_OPTIONAL);
 
     VIR_DOMAIN_CAPS_ENUM_SET(hostdev->subsysType,
-                             VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB,
                              VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI,
                              VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI);
 
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PIIX3_USB_UHCI) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_PIIX4_USB_UHCI) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_USB_EHCI) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_ICH9_USB_EHCI1) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_VT82C686B_USB_UHCI) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_OHCI) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_NEC_USB_XHCI) ||
+        virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_QEMU_XHCI)) {
+        VIR_DOMAIN_CAPS_ENUM_SET(hostdev->subsysType,
+                                 VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB);
+    }
+
     /* No virDomainHostdevCapsType for QEMU */
     virDomainCapsEnumClear(&hostdev->capsType);
 

tests/domaincapsdata/qemu_2.10.0.s390x.xml

@@ -168,7 +168,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_2.11.0.s390x.xml

@@ -167,7 +167,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_2.12.0.s390x.xml

@@ -166,7 +166,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_2.7.0.s390x.xml

@@ -71,7 +71,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_2.8.0.s390x.xml

@@ -152,7 +152,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_2.9.0.s390x.xml

@@ -153,7 +153,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_3.0.0.s390x.xml

@@ -173,7 +173,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_4.0.0.s390x.xml

@@ -178,7 +178,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>

tests/domaincapsdata/qemu_4.2.0.s390x.xml

@@ -172,7 +172,6 @@
         <value>optional</value>
       </enum>
       <enum name='subsysType'>
-        <value>usb</value>
         <value>pci</value>
         <value>scsi</value>
       </enum>