Re: [Qemu-devel] [PATCH 07/11] pc: set APIC ID based on socket/core/thread ids if it's not been set yet

[Eduardo Habkost]

On Thu, Jun 23, 2016 at 04:54:25PM +0200, Igor Mammedov wrote:
> CPU added with device_add help won't have APIC ID set,
> so set it according to socket/core/thread ids provided
> with device_add command.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/i386/pc.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 87352ae..63e9bb6 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1758,13 +1758,23 @@ static void pc_cpu_pre_plug(HotplugHandler 
> *hotplug_dev,
>                              DeviceState *dev, Error **errp)
>  {
>      int idx;
> +    CPUArchId *cpu_slot;
> +    X86CPUTopoInfo topo;
>      X86CPU *cpu = X86_CPU(dev);
>      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> -    CPUArchId *cpu_slot = pc_find_cpu(pcms, CPU(dev), &idx);
>  
> +    if (cpu->apic_id == 0xFFFFFFFF) {
> +        /* APIC ID not set, set it based on socket/core/thread properties */
> +        X86CPUTopoInfo topo = { cpu->socket, cpu->core, cpu->thread };
> +        cpu->apic_id = apicid_from_topo_ids(smp_cores, smp_threads, &topo);
> +    }

What happens if neither apic-id or socket/core/thread are set?

apicid_from_topo_ids() needs the caller to ensure
core_id < nr_cores && smt_id < nr_threads. Do you do that?

> +
> +    cpu_slot = pc_find_cpu(pcms, CPU(dev), &idx);
>      if (!cpu_slot) {
> -        error_setg(errp, "Invalid CPU index with APIC ID (%" PRIu32
> -                   "), valid range 0:%d", cpu->apic_id,
> +        x86_topo_ids_from_apicid(cpu->apic_id, smp_cores, smp_threads, 
> &topo);
> +        error_setg(errp, "Invalid CPU[socket: %d, core: %d, thread: %d] with"
> +                  " APIC ID (%" PRIu32 "), valid index range 0:%d",
> +                   topo.pkg_id, topo.core_id, topo.smt_id, cpu->apic_id,
>                     pcms->possible_cpus->len - 1);

The error message is a bit confusing: the interface is not based
on CPU index anymore, but it still says "valid index range 0:%d".

>          return;
>      }
> @@ -1780,8 +1790,6 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
>       * added CPUs so that query_hotpluggable_cpus would show correct values
>       */
>      if (cpu->thread == -1 || cpu->core == -1 || cpu->socket == -1) {
> -        X86CPUTopoInfo topo;
> -
>          x86_topo_ids_from_apicid(cpu->apic_id, smp_cores, smp_threads, 
> &topo);
>          cpu->thread = topo.smt_id;
>          cpu->core = topo.core_id;
> -- 
> 1.8.3.1
> 

-- 
Eduardo