guest: Enable USB for RISC-V virt guests

Unlike other features we have enabled earlier, this one requires
version checks because RISC-V guests have only started using PCI
by default very recently, and we can't have USB without PCI.

More specifically, we need QEMU commit d6c1bd4a2237 (included
in 4.0.0) and libvirt commit 7c48fb08e0cd (included in 5.3.0).

Reviewed-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Andrea Bolognani <abologna@redhat.com>

tests/cli-test-xml/compare/virt-install-riscv64-graphics.xml

@@ -21,6 +21,7 @@
       <source file="/dev/default-pool/testvol1.img"/>
       <target dev="vda" bus="virtio"/>
     </disk>
+    <controller type="usb" index="0" model="qemu-xhci" ports="15"/>
     <interface type="bridge">
       <source bridge="eth0"/>
       <mac address="00:11:22:33:44:55"/>

tests/cli-test-xml/compare/virt-install-riscv64-headless.xml

@@ -21,6 +21,7 @@
       <source file="/dev/default-pool/testvol1.img"/>
       <target dev="vda" bus="virtio"/>
     </disk>
+    <controller type="usb" index="0" model="qemu-xhci" ports="15"/>
     <interface type="bridge">
       <source bridge="eth0"/>
       <mac address="00:11:22:33:44:55"/>

tests/clitest.py

@@ -812,7 +812,7 @@ c.add_compare("--connect %(URI-KVM-AARCH64)s --disk size=1 --os-variant fedora22
 c = vinst.add_category("kvm-headless", "--os-variant fedora29 --import --disk %(EXISTIMG1)s --network default --graphics none")
 c.add_compare("--connect %(URI-KVM-AARCH64)s --arch aarch64", "aarch64-headless")
 c.add_compare("--connect %(URI-KVM-PPC64LE)s --arch ppc64le", "ppc64-headless")
-c.add_compare("--connect %(URI-QEMU-RISCV64)s --arch riscv64", "riscv64-headless")
+c.add_compare("--connect %(URI-QEMU-RISCV64)s --arch riscv64", "riscv64-headless", check_version="5.3.0")
 c.add_compare("--connect %(URI-KVM-S390X)s --arch s390x", "s390x-headless")
 c.add_compare("--connect %(URI-KVM)s --arch x86_64", "x86_64-headless")
 
@@ -821,7 +821,7 @@ c.add_compare("--connect %(URI-KVM)s --arch x86_64", "x86_64-headless")
 c = vinst.add_category("kvm-graphics", "--os-variant fedora29 --import --disk %(EXISTIMG1)s --network default --graphics vnc")
 c.add_compare("--connect %(URI-KVM-AARCH64)s --arch aarch64", "aarch64-graphics")
 c.add_compare("--connect %(URI-KVM-PPC64LE)s --arch ppc64le", "ppc64-graphics")
-c.add_compare("--connect %(URI-QEMU-RISCV64)s --arch riscv64", "riscv64-graphics")
+c.add_compare("--connect %(URI-QEMU-RISCV64)s --arch riscv64", "riscv64-graphics", check_version="5.3.0")
 c.add_compare("--connect %(URI-KVM-S390X)s --arch s390x", "s390x-graphics")
 c.add_compare("--connect %(URI-KVM)s --arch x86_64", "x86_64-graphics")
 

virtinst/guest.py

@@ -784,6 +784,14 @@ class Guest(XMLBuilder):
                 self.conn.check_support(
                         self.conn.SUPPORT_CONN_MACHVIRT_PCI_DEFAULT)):
                 usb3 = True
+        elif self.os.is_riscv_virt():
+            # For RISC-V we can assume the guest OS supports USB3, but we
+            # have to make sure libvirt and QEMU are new enough to be using
+            # PCI by default
+            if (qemu_usb3 and
+                self.conn.check_support(
+                        self.conn.SUPPORT_CONN_RISCV_VIRT_PCI_DEFAULT)):
+                usb3 = True
         elif self.os.is_pseries():
             # For pseries, we always assume OS supports usb3
             if qemu_usb3:

virtinst/support.py

@@ -265,6 +265,7 @@ SUPPORT_CONN_MACHVIRT_PCI_DEFAULT = _make(version="3.0.0")
 SUPPORT_CONN_QEMU_XHCI = _make(version="3.3.0", hv_version={"qemu": "2.9.0"})
 SUPPORT_CONN_VNC_NONE_AUTH = _make(hv_version={"qemu": "2.9.0"})
 SUPPORT_CONN_DEVICE_BOOT_ORDER = _make(hv_version={"qemu": 0, "test": 0})
+SUPPORT_CONN_RISCV_VIRT_PCI_DEFAULT = _make(version="5.3.0", hv_version={"qemu": "4.0.0"})
 
 # We choose qemu 2.11.0 as the first version to target for q35 default.
 # That's not really based on anything except reasonably modern at the