target/ppc/kvm: Fix const violation when trimming CPU alias suffix

GCC 16 tightens diagnostics around const correctness and now correctly
rejects attempts to modify strings referenced through const-qualified
pointers. In kvm_ppc_register_host_cpu_type(), ppc_cpu_aliases[i].model
is defined as const char *, but the code was using strstr() on it and
then modifying the returned pointer in-place to strip
POWERPC_CPU_TYPE_SUFFIX.

This results in a write through a pointer derived from const data,
triggering a build failure with GCC 16:

  error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
        suffix = strstr(ppc_cpu_aliases[i].model, POWERPC_CPU_TYPE_SUFFIX);
               ^

Fix this by changing suffix to 'const gchar *' and using g_strstr_len()
to locate the suffix, then allocating a new string with g_strndup() (to
copy only the prefix) or g_strdup() (to copy the entire name if no
suffix exists). This maintains const correctness throughout while
preserving the original functionality.

No functional change intended.

Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Tested-by: Anushree Mathur <anushree.mathur@linux.ibm.com>
Reviewed-by: Aditya Gupta <adityag@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260518172517.12466-2-amachhiw@linux.ibm.com
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 25c28ad089c61439607e64f7b41504a0cbc0e230..b94c2997a07f9465fac6304c21eeee1e6ac04c08 100644 (file)
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -2654,13 +2654,12 @@ static int kvm_ppc_register_host_cpu_type(void)
     dc = DEVICE_CLASS(ppc_cpu_get_family_class(pvr_pcc));
     for (i = 0; ppc_cpu_aliases[i].alias != NULL; i++) {
         if (g_ascii_strcasecmp(ppc_cpu_aliases[i].alias, dc->desc) == 0) {
-            char *suffix;
+            const gchar *suffix, *cname = object_class_get_name(oc);
+
+            suffix = g_strstr_len(cname, -1, POWERPC_CPU_TYPE_SUFFIX);
+            ppc_cpu_aliases[i].model = suffix ?
+                g_strndup(cname, (gsize)(suffix - cname)) : g_strdup(cname);
 
-            ppc_cpu_aliases[i].model = g_strdup(object_class_get_name(oc));
-            suffix = strstr(ppc_cpu_aliases[i].model, POWERPC_CPU_TYPE_SUFFIX);
-            if (suffix) {
-                *suffix = 0;
-            }
             break;
         }
     }