Fix pci bus naming for PPC

Recent discussions around naming of 'pci' vs 'pci.0' for PPC
made me go back and look at the PPC emulator in every historical
version of QEMU since 1.0. The results were worse than I imagined.
This patch adds the logic required to make libvirt work with PPC
correctly with naming variations across all versions & machine
types.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/qemu/qemu_capabilities.c

@@ -1928,6 +1928,56 @@ virQEMUCapsGet(virQEMUCapsPtr qemuCaps,
 }
 
 
+bool virQEMUCapsHasPCIMultiBus(virQEMUCapsPtr qemuCaps,
+                               virDomainDefPtr def)
+{
+    bool hasMultiBus = virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_MULTIBUS);
+
+    if (hasMultiBus)
+        return true;
+
+    if (def->os.arch == VIR_ARCH_PPC ||
+        def->os.arch == VIR_ARCH_PPC64) {
+        /*
+         * Usage of pci.0 naming:
+         *
+         *    ref405ep: no pci
+         *       taihu: no pci
+         *      bamboo: 1.1.0
+         *       mac99: 2.0.0
+         *     g3beige: 2.0.0
+         *        prep: 1.4.0
+         *     pseries: 2.0.0
+         *   mpc8544ds: forever
+         * virtex-m507: no pci
+         *     ppce500: 1.6.0
+         */
+
+        if (qemuCaps->version >= 2000000)
+            return true;
+
+        if (qemuCaps->version >= 1006000 &&
+            STREQ(def->os.machine, "ppce500"))
+            return true;
+
+        if (qemuCaps->version >= 1004000 &&
+            STREQ(def->os.machine, "prep"))
+            return true;
+
+        if (qemuCaps->version >= 1001000 &&
+            STREQ(def->os.machine, "bamboo"))
+            return true;
+
+        if (STREQ(def->os.machine, "mpc8544ds"))
+            return true;
+
+        return false;
+    }
+
+    return false;
+}
+
+
 const char *virQEMUCapsGetBinary(virQEMUCapsPtr qemuCaps)
 {
     return qemuCaps->binary;
@@ -2809,15 +2859,22 @@ virQEMUCapsInitHelp(virQEMUCapsPtr qemuCaps, uid_t runUid, gid_t runGid)
                                 false) < 0)
         goto cleanup;
 
-    /* Currently only x86_64 and i686 support PCI-multibus. */
+    /* x86_64 and i686 support PCI-multibus on all machine types
+     * since forever. For other architectures, it has been changing
+     * across releases, per machine type, so we can't simply detect
+     * it here. Thus the rest of the logic is provided in a separate
+     * helper virQEMUCapsHasPCIMultiBus() which keys off the machine
+     * stored in virDomainDef and QEMU version number
+     */
     if (qemuCaps->arch == VIR_ARCH_X86_64 ||
-        qemuCaps->arch == VIR_ARCH_I686) {
+        qemuCaps->arch == VIR_ARCH_I686)
         virQEMUCapsSet(qemuCaps, QEMU_CAPS_PCI_MULTIBUS);
-    } else {
-        /* -no-acpi is not supported on other archs
-         * even if qemu reports it in -help */
+
+    /* -no-acpi is not supported on non-x86
+     * even if qemu reports it in -help */
+    if (qemuCaps->arch != VIR_ARCH_X86_64 &&
+        qemuCaps->arch != VIR_ARCH_I686)
         virQEMUCapsClear(qemuCaps, QEMU_CAPS_NO_ACPI);
-    }
 
     /* virQEMUCapsExtractDeviceStr will only set additional caps if qemu
      * understands the 0.13.0+ notion of "-device driver,".  */
@@ -2934,9 +2991,14 @@ virQEMUCapsInitArchQMPBasic(virQEMUCapsPtr qemuCaps,
         goto cleanup;
     }
 
-    /*
-     * Currently only x86_64 and i686 support PCI-multibus,
-     * -no-acpi and -no-kvm-pit-reinjection.
+    /* x86_64 and i686 support PCI-multibus on all machine types
+     * since forever. For other architectures, it has been changing
+     * across releases, per machine type, so we can't simply detect
+     * it here. Thus the rest of the logic is provided in a separate
+     * helper virQEMUCapsHasPCIMultiBus() which keys off the machine
+     * stored in virDomainDef and QEMU version number
+     *
+     * ACPI/HPET/KVM PIT are also x86 specific
      */
     if (qemuCaps->arch == VIR_ARCH_X86_64 ||
         qemuCaps->arch == VIR_ARCH_I686) {

src/qemu/qemu_capabilities.h

@@ -239,6 +239,9 @@ void virQEMUCapsClear(virQEMUCapsPtr qemuCaps,
 bool virQEMUCapsGet(virQEMUCapsPtr qemuCaps,
                     enum virQEMUCapsFlags flag);
 
+bool virQEMUCapsHasPCIMultiBus(virQEMUCapsPtr qemuCaps,
+                               virDomainDefPtr def);
+
 char *virQEMUCapsFlagsString(virQEMUCapsPtr qemuCaps);
 
 const char *virQEMUCapsGetBinary(virQEMUCapsPtr qemuCaps);

src/qemu/qemu_command.c

@@ -3076,7 +3076,7 @@ qemuBuildDeviceAddressStr(virBufferPtr buf,
                 goto cleanup;
             }
         } else {
-            if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_PCI_MULTIBUS)) {
+            if (virQEMUCapsHasPCIMultiBus(qemuCaps, domainDef)) {
                 virBufferAsprintf(buf, ",bus=%s", contAlias);
             } else {
                 virBufferAddLit(buf, ",bus=pci");