target/ppc: Avoid printing wrong aliases in CPU help text

When running with KVM, we update the "family" CPU alias to point
to the right host CPU type, so that it for example possible to
use "-cpu POWER8" on a POWER8NVL host. However, the function for
printing the list of available CPU models is called earlier than
the KVM setup code, so the output of "-cpu help" is wrong in that
case. Since it would be somewhat ugly anyway to have different
help texts depending on whether "-enable-kvm" has been specified
or not, we should better always print the same text, so fix this
issue by printing "alias for preferred XXX CPU" instead.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

target/ppc/cpu.h

@@ -1225,6 +1225,7 @@ static inline PowerPCCPU *ppc_env_get_cpu(CPUPPCState *env)
 
 PowerPCCPUClass *ppc_cpu_class_by_pvr(uint32_t pvr);
 PowerPCCPUClass *ppc_cpu_class_by_pvr_mask(uint32_t pvr);
+PowerPCCPUClass *ppc_cpu_get_family_class(PowerPCCPUClass *pcc);
 
 struct PPCVirtualHypervisor {
     Object parent;

target/ppc/kvm.c

@@ -2424,18 +2424,6 @@ bool kvmppc_has_cap_mmu_hash_v3(void)
     return cap_mmu_hash_v3;
 }
 
-static PowerPCCPUClass *ppc_cpu_get_family_class(PowerPCCPUClass *pcc)
-{
-    ObjectClass *oc = OBJECT_CLASS(pcc);
-
-    while (oc && !object_class_is_abstract(oc)) {
-        oc = object_class_get_parent(oc);
-    }
-    assert(oc);
-
-    return POWERPC_CPU_CLASS(oc);
-}
-
 PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void)
 {
     uint32_t host_pvr = mfpvr();

target/ppc/translate_init.c

@@ -10285,6 +10285,18 @@ PowerPCCPU *cpu_ppc_init(const char *cpu_model)
     return POWERPC_CPU(cpu_generic_init(TYPE_POWERPC_CPU, cpu_model));
 }
 
+PowerPCCPUClass *ppc_cpu_get_family_class(PowerPCCPUClass *pcc)
+{
+    ObjectClass *oc = OBJECT_CLASS(pcc);
+
+    while (oc && !object_class_is_abstract(oc)) {
+        oc = object_class_get_parent(oc);
+    }
+    assert(oc);
+
+    return POWERPC_CPU_CLASS(oc);
+}
+
 /* Sort by PVR, ordering special case "host" last. */
 static gint ppc_cpu_list_compare(gconstpointer a, gconstpointer b)
 {
@@ -10316,6 +10328,7 @@ static void ppc_cpu_list_entry(gpointer data, gpointer user_data)
     ObjectClass *oc = data;
     CPUListState *s = user_data;
     PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc);
+    DeviceClass *family = DEVICE_CLASS(ppc_cpu_get_family_class(pcc));
     const char *typename = object_class_get_name(oc);
     char *name;
     int i;
@@ -10338,8 +10351,18 @@ static void ppc_cpu_list_entry(gpointer data, gpointer user_data)
         if (alias_oc != oc) {
             continue;
         }
-        (*s->cpu_fprintf)(s->file, "PowerPC %-16s (alias for %s)\n",
-                          alias->alias, name);
+        /*
+         * If running with KVM, we might update the family alias later, so
+         * avoid printing the wrong alias here and use "preferred" instead
+         */
+        if (strcmp(alias->alias, family->desc) == 0) {
+            (*s->cpu_fprintf)(s->file,
+                              "PowerPC %-16s (alias for preferred %s CPU)\n",
+                              alias->alias, family->desc);
+        } else {
+            (*s->cpu_fprintf)(s->file, "PowerPC %-16s (alias for %s)\n",
+                              alias->alias, name);
+        }
     }
     g_free(name);
 }