qemu: Fix command line generation with faked host CPU

The code expected that host CPU architecture matches the architecture on
which libvirt runs. This is normally true but not in tests, where host
CPU is faked to produce consistent results.

src/qemu/qemu_command.c

@@ -2440,7 +2440,8 @@ qemuBuildCpuArgStr(const struct qemud_driver *driver,
     *hasHwVirt = false;
 
     if (def->cpu && def->cpu->model) {
-        if (qemuCapsProbeCPUModels(emulator, qemuCmdFlags, ut->machine,
+        if (host &&
+            qemuCapsProbeCPUModels(emulator, qemuCmdFlags, host->arch,
                                    &ncpus, &cpus) < 0)
             goto cleanup;
 
@@ -2469,7 +2470,7 @@ qemuBuildCpuArgStr(const struct qemud_driver *driver,
             break;
         }
 
-        if (VIR_ALLOC(guest) < 0 || !(guest->arch = strdup(ut->machine)))
+        if (VIR_ALLOC(guest) < 0 || !(guest->arch = strdup(host->arch)))
             goto no_memory;
 
         if (def->cpu->match == VIR_CPU_MATCH_MINIMUM)
@@ -2528,8 +2529,9 @@ qemuBuildCpuArgStr(const struct qemud_driver *driver,
     ret = 0;
 
 cleanup:
+    if (guest)
+        cpuDataFree(guest->arch, data);
     virCPUDefFree(guest);
-    cpuDataFree(ut->machine, data);
 
     if (cpus) {
         for (i = 0; i < ncpus; i++)