Re: [Qemu-devel] [PATCH] ppc/kvm: have the "family" CPU alias to point to TYPE_HOST_POWERPC_CPU

[Thomas Huth <thuth@redhat.com>]

On 05.07.2017 10:49, Greg Kurz wrote:
> When running KVM on POWER, we allow the user to pass "-cpu POWERx" instead
> of "-cpu host". This is achieved by patching the ppc_cpu_aliases[] array
> so that "POWERx" points to the CPU class with the same PVR as the host CPU.
> This causes CPUs to be instantiated from this CPU class instead of the
> TYPE_HOST_POWERPC_CPU class which is used with "-cpu host". These CPUs thus
> miss all the KVM specific tuning from kvmppc_host_cpu_class_init().
> 
> This currently causes QEMU with "-cpu POWER9" to fail when running KVM on a
> POWER9 DD1 host:
> 
> qemu-system-ppc64: Register sync failed... If you're using kvm-hv.ko, only
>  "-cpu host" is possible
> kvm_init_vcpu failed: Invalid argument
> 
> Let's have the "POWERx" alias to point to TYPE_HOST_POWERPC_CPU directly,
> so that "-cpu POWERx" instantiates CPUs from the same class as "-cpu host".
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  target/ppc/kvm.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index f2f7c531bc7b..f7a7ea5858a3 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2445,6 +2445,7 @@ static int kvm_ppc_register_host_cpu_type(void)
>          .class_init = kvmppc_host_cpu_class_init,
>      };
>      PowerPCCPUClass *pvr_pcc;
> +    ObjectClass *oc;
>      DeviceClass *dc;
>      int i;
>  
> @@ -2455,6 +2456,9 @@ static int kvm_ppc_register_host_cpu_type(void)
>      type_info.parent = object_class_get_name(OBJECT_CLASS(pvr_pcc));
>      type_register(&type_info);
>  
> +    oc = object_class_by_name(type_info.name);
> +    g_assert(oc);
> +
>  #if defined(TARGET_PPC64)
>      type_info.name = g_strdup_printf("%s-"TYPE_SPAPR_CPU_CORE, "host");
>      type_info.parent = TYPE_SPAPR_CPU_CORE,
> @@ -2474,7 +2478,6 @@ 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 (strcmp(ppc_cpu_aliases[i].alias, dc->desc) == 0) {
> -            ObjectClass *oc = OBJECT_CLASS(pvr_pcc);
>              char *suffix;
>  
>              ppc_cpu_aliases[i].model = g_strdup(object_class_get_name(oc));
> 

Yes, I think that should be fine, too.

Reviewed-by: Thomas Huth <thuth@redhat.com>