Re: [PATCH v2] target/ppc/kvm: Fix const violation when trimming CPU alias suffix

[Gautam Menghani <gautam@linux.ibm.com>]

On Fri, May 08, 2026 at 01:44:16PM +0530, Amit Machhiwal wrote:
> 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 declared 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 duplicating the model string into a mutable buffer using
> g_strdup(), trimming the suffix on that temporary buffer, and only then
> storing it in the alias table.
> 
> This preserves the existing behavior while avoiding modification of
> const data and ensures compatibility with newer compilers.
> 
> No functional change intended.
> 
> Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
> ---
> Changes in v2:
>   * trim the duplicated buffer before assigning it to ppc_cpu_aliases[i].model
> ---
> 
>  target/ppc/kvm.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 25c28ad089c6..c2843b1421cb 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2654,13 +2654,14 @@ 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;
> +            char *model, *suffix;
>  
> -            ppc_cpu_aliases[i].model = g_strdup(object_class_get_name(oc));
> -            suffix = strstr(ppc_cpu_aliases[i].model, POWERPC_CPU_TYPE_SUFFIX);
> +            model = g_strdup(object_class_get_name(oc));
> +            suffix = strstr(model, POWERPC_CPU_TYPE_SUFFIX);
>              if (suffix) {
>                  *suffix = 0;
>              }
> +            ppc_cpu_aliases[i].model = model;
>              break;
>          }
>      }
> 


Reviewed-by: Gautam Menghani <gautam@linux.ibm.com>

> base-commit: ee7eb612be8f8886d48c1d0c1f1c65e495138f83
> -- 
> 2.50.1 (Apple Git-155)
> 
>