Re: [Qemu-devel] [PATCH v3 04/13] acpi: cphp: force switch to modern cpu hotplug if APIC ID > 254

[Eduardo Habkost]

On Thu, Oct 13, 2016 at 11:52:38AM +0200, Igor Mammedov wrote:
> Switch to modern cpu hotplug at machine startup time if
> a cpu present at boot has apic-id in range unsupported
> by legacy cpu hotplug interface (i.e. > 254), to avoid
> killing QEMU from legacy cpu hotplug code with error:
>    "acpi: invalid cpu id: #apic-id#"
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  hw/acpi/cpu_hotplug.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/acpi/cpu_hotplug.c b/hw/acpi/cpu_hotplug.c
> index e19d902..c2ab9b8 100644
> --- a/hw/acpi/cpu_hotplug.c
> +++ b/hw/acpi/cpu_hotplug.c
> @@ -63,7 +63,8 @@ static void acpi_set_cpu_present_bit(AcpiCpuHotplug *g, 
> CPUState *cpu,
>  
>      cpu_id = k->get_arch_id(cpu);
>      if ((cpu_id / 8) >= ACPI_GPE_PROC_LEN) {
> -        error_setg(errp, "acpi: invalid cpu id: %" PRIi64, cpu_id);
> +        object_property_set_bool(g->device, false, "cpu-hotplug-legacy",
> +                                 &error_abort);

What happens we are in legacy mode and this is triggered during
hotplug instead of machine init? Would it break something, or is
it safe?

Unrelated to this patch: piix4_set_cpu_hotplug_legacy() has an
assert(!value). I assume this means we must replace the QOM
property with something that the user can't fiddle with, right?

>          return;
>      }
>  
> @@ -85,13 +86,14 @@ void legacy_acpi_cpu_hotplug_init(MemoryRegion *parent, 
> Object *owner,
>  {
>      CPUState *cpu;
>  
> -    CPU_FOREACH(cpu) {
> -        acpi_set_cpu_present_bit(gpe_cpu, cpu, &error_abort);
> -    }
>      memory_region_init_io(&gpe_cpu->io, owner, &AcpiCpuHotplug_ops,
>                            gpe_cpu, "acpi-cpu-hotplug", ACPI_GPE_PROC_LEN);
>      memory_region_add_subregion(parent, base, &gpe_cpu->io);
>      gpe_cpu->device = owner;
> +
> +    CPU_FOREACH(cpu) {
> +        acpi_set_cpu_present_bit(gpe_cpu, cpu, &error_abort);
> +    }
>  }
>  
>  void acpi_switch_to_modern_cphp(AcpiCpuHotplug *gpe_cpu,
> -- 
> 2.7.4
> 

-- 
Eduardo