qemu: Always format CPU topology

When libvirt cannot find a suitable CPU model for host CPU (easily
reproducible by running libvirt in a guest), it would not provide CPU
topology in capabilities XML either. Even though CPU topology is known
and can be queried by virNodeGetInfo. With this patch, CPU topology will
always be provided in capabilities XML regardless on the presence of CPU
model.

src/qemu/qemu_capabilities.c

@@ -685,6 +685,7 @@ qemuCapsInitGuest(virCapsPtr caps,
     nmachines = 0;
 
     if (caps->host.cpu &&
+        caps->host.cpu->model &&
         qemuCapsGetCPUDefinitions(qemubinCaps, NULL) > 0 &&
         !virCapabilitiesAddGuestFeature(guest, "cpuselection", 1, 0))
         goto error;
@@ -781,12 +782,11 @@ qemuCapsInitCPU(virCapsPtr caps,
     cpu->sockets = nodeinfo.sockets;
     cpu->cores = nodeinfo.cores;
     cpu->threads = nodeinfo.threads;
+    caps->host.cpu = cpu;
 
     if (!(data = cpuNodeData(arch))
         || cpuDecode(cpu, data, NULL, 0, NULL) < 0)
-        goto error;
-
-    caps->host.cpu = cpu;
+        goto cleanup;
 
     ret = 0;
 

src/qemu/qemu_command.c

@@ -4100,6 +4100,7 @@ qemuBuildCpuArgStr(const struct qemud_driver *driver,
         int hasSVM;
 
         if (!host ||
+            !host->model ||
             (ncpus = qemuCapsGetCPUDefinitions(caps, &cpus)) == 0) {
             virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                            _("CPU specification not supported by hypervisor"));

src/qemu/qemu_domain.c

@@ -1227,7 +1227,9 @@ qemuDomainDefFormatBuf(struct qemud_driver *driver,
     if ((flags & VIR_DOMAIN_XML_UPDATE_CPU) &&
         def_cpu &&
         (def_cpu->mode != VIR_CPU_MODE_CUSTOM || def_cpu->model)) {
-        if (!driver->caps || !driver->caps->host.cpu) {
+        if (!driver->caps ||
+            !driver->caps->host.cpu ||
+            !driver->caps->host.cpu->model) {
             virReportError(VIR_ERR_OPERATION_FAILED,
                            "%s", _("cannot get host CPU capabilities"));
             goto cleanup;

src/qemu/qemu_driver.c

@@ -10180,7 +10180,8 @@ qemuCPUCompare(virConnectPtr conn,
     if (!driver->caps) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        "%s", _("cannot get host capabilities"));
-    } else if (!driver->caps->host.cpu) {
+    } else if (!driver->caps->host.cpu ||
+               !driver->caps->host.cpu->model) {
         VIR_WARN("cannot get host CPU capabilities");
         ret = VIR_CPU_COMPARE_INCOMPATIBLE;
     } else {