qemu: Add PCI support for RISC-V guests

virtio-mmio is still used by default, so if PCI is desired
it's necessary to explicitly opt-in by adding an appropriate

  <address type='pci' domain='0x0000' ... />

element to the corresponding device.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_capabilities.c

@@ -1732,11 +1732,12 @@ bool virQEMUCapsHasPCIMultiBus(virQEMUCapsPtr qemuCaps,
     if (ARCH_IS_S390(def->os.arch))
         return true;
 
-    /* If ARM 'virt' supports PCI, it supports multibus.
-     * No extra conditions here for simplicity.
-     */
-    if (qemuDomainIsARMVirt(def))
+    /* If the virt machine, both on ARM and RISC-V, supports PCI,
+     * then it also supports multibus */
+    if (qemuDomainIsARMVirt(def) ||
+        qemuDomainIsRISCVVirt(def)) {
         return true;
+    }
 
     return false;
 }

src/qemu/qemu_domain.c

@@ -3380,6 +3380,8 @@ qemuDomainDefAddDefaultDevices(virDomainDefPtr def,
     case VIR_ARCH_RISCV32:
     case VIR_ARCH_RISCV64:
         addDefaultUSB = false;
+        if (qemuDomainIsRISCVVirt(def))
+            addPCIeRoot = virQEMUCapsGet(qemuCaps, QEMU_CAPS_OBJECT_GPEX);
         break;
 
     case VIR_ARCH_S390:

src/qemu/qemu_domain_address.c

@@ -2369,7 +2369,8 @@ qemuDomainSupportsPCI(virDomainDefPtr def,
     if (STREQ(def->os.machine, "versatilepb"))
         return true;
 
-    if (qemuDomainIsARMVirt(def) &&
+    if ((qemuDomainIsARMVirt(def) ||
+         qemuDomainIsRISCVVirt(def)) &&
         virQEMUCapsGet(qemuCaps, QEMU_CAPS_OBJECT_GPEX))
         return true;