Re: [PATCH v3 5/5] hw/loongarch/virt: Enable cpu hotplug feature on virt machine

[Igor Mammedov <imammedo@redhat.com>]

On Mon,  4 Nov 2024 14:34:35 +0800
Bibo Mao <maobibo@loongson.cn> wrote:

> On virt machine, enable CPU hotplug feature has_hotpluggable_cpus. For
> hot-added CPUs after power on, interrupt pin of extioi and ipi interrupt
> controller need connect to pins of new CPU.
> 
> Also change num-cpu property of extioi and ipi from smp.cpus to
> smp.max_cpus
> 
> Co-developed-by: Xianglai Li <lixianglai@loongson.cn>
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
>  hw/loongarch/virt.c         | 57 +++++++++++++++++++++++++++++++++----
>  include/hw/loongarch/virt.h |  2 ++
>  2 files changed, 54 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index e73f689c83..6673493109 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -891,8 +891,9 @@ static void virt_irq_init(LoongArchVirtMachineState *lvms)
>  
>      /* Create IPI device */
>      ipi = qdev_new(TYPE_LOONGARCH_IPI);
> -    qdev_prop_set_uint32(ipi, "num-cpu", ms->smp.cpus);
> +    qdev_prop_set_uint32(ipi, "num-cpu", ms->smp.max_cpus);
>      sysbus_realize_and_unref(SYS_BUS_DEVICE(ipi), &error_fatal);
> +    lvms->ipi = ipi;
>  
>      /* IPI iocsr memory region */
>      memory_region_add_subregion(&lvms->system_iocsr, SMP_IPI_MAILBOX,
> @@ -905,11 +906,12 @@ static void virt_irq_init(LoongArchVirtMachineState *lvms)
>  
>      /* Create EXTIOI device */
>      extioi = qdev_new(TYPE_LOONGARCH_EXTIOI);
> -    qdev_prop_set_uint32(extioi, "num-cpu", ms->smp.cpus);
> +    qdev_prop_set_uint32(extioi, "num-cpu", ms->smp.max_cpus);
>      if (virt_is_veiointc_enabled(lvms)) {
>          qdev_prop_set_bit(extioi, "has-virtualization-extension", true);
>      }
>      sysbus_realize_and_unref(SYS_BUS_DEVICE(extioi), &error_fatal);
> +    lvms->extioi = extioi;
>      memory_region_add_subregion(&lvms->system_iocsr, APIC_BASE,
>                      sysbus_mmio_get_region(SYS_BUS_DEVICE(extioi), 0));
>      if (virt_is_veiointc_enabled(lvms)) {
> @@ -1403,8 +1405,40 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
>       }
>  
>      if (cpu->phy_id == UNSET_PHY_ID) {
> -        error_setg(&local_err, "CPU hotplug not supported");
> -        goto out;
> +        if ((cpu->thread_id < 0) || (cpu->thread_id >= ms->smp.threads)) {
> +            error_setg(&local_err,
> +                       "Invalid thread-id %u specified, must be in range 1:%u",
> +                       cpu->thread_id, ms->smp.threads - 1);
> +            goto out;
> +        }
> +
> +        if ((cpu->core_id < 0) || (cpu->core_id >= ms->smp.cores)) {
> +            error_setg(&local_err,
> +                       "Invalid core-id %u specified, must be in range 1:%u",
> +                       cpu->core_id, ms->smp.cores - 1);
> +            goto out;
> +        }
> +
> +        if ((cpu->socket_id < 0) || (cpu->socket_id >= ms->smp.sockets)) {
> +            error_setg(&local_err,
> +                       "Invalid socket-id %u specified, must be in range 1:%u",
> +                       cpu->socket_id, ms->smp.sockets - 1);
> +            goto out;
> +        }
> +
> +        topo.socket_id = cpu->socket_id;
> +        topo.core_id = cpu->core_id;
> +        topo.thread_id = cpu->thread_id;
> +        arch_id =  virt_get_arch_id_from_topo(ms, &topo);
> +        cpu_slot = virt_find_cpu_slot(ms, arch_id, &index);
> +        if (CPU(cpu_slot->cpu)) {
> +            error_setg(&local_err,
> +                       "cpu(id%d=%d:%d:%d) with arch-id %" PRIu64 " exists",
> +                       cs->cpu_index, cpu->socket_id, cpu->core_id,
> +                       cpu->thread_id, cpu_slot->arch_id);
> +            goto out;
> +        }
> +        cpu->phy_id = arch_id;
>      } else {
>          /*
>           * For cold-add cpu, topo property is not set. And only physical id
> @@ -1484,10 +1518,22 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
>                                  DeviceState *dev, Error **errp)
>  {
>      CPUArchId *cpu_slot;
> +    Error *local_err = NULL;
>      LoongArchCPU *cpu = LOONGARCH_CPU(dev);
> +    MachineState *ms = MACHINE(hotplug_dev);
>      LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
>  
> -    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id, NULL);
> +    if (lvms->acpi_ged) {
> +        /* Connect irq to cpu, including ipi and extioi irqchip */

> +        virt_init_cpu_irq(ms, CPU(cpu));

why it depends on GED?
Can't you just call it unconditionally here for both hotplugged and coldplugged CPUs?
/and drop this call from for() loop of coldplug CPUs/

> +        hotplug_handler_plug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            return;
> +        }
> +    }
> +
> +    cpu_slot = virt_find_cpu_slot(ms, cpu->phy_id, NULL);
>      cpu_slot->cpu = CPU(dev);
>      return;
>  }
> @@ -1671,6 +1717,7 @@ static void virt_class_init(ObjectClass *oc, void *data)
>      mc->numa_mem_supported = true;
>      mc->auto_enable_numa_with_memhp = true;
>      mc->auto_enable_numa_with_memdev = true;
> +    mc->has_hotpluggable_cpus = true;
>      mc->get_hotplug_handler = virt_get_hotplug_handler;
>      mc->default_nic = "virtio-net-pci";
>      hc->plug = virt_device_plug_cb;
> diff --git a/include/hw/loongarch/virt.h b/include/hw/loongarch/virt.h
> index 861034d614..79a85723c9 100644
> --- a/include/hw/loongarch/virt.h
> +++ b/include/hw/loongarch/virt.h
> @@ -61,6 +61,8 @@ struct LoongArchVirtMachineState {
>      MemoryRegion iocsr_mem;
>      AddressSpace as_iocsr;
>      struct loongarch_boot_info bootinfo;
> +    DeviceState *ipi;
> +    DeviceState *extioi;
>  };
>  
>  #define TYPE_LOONGARCH_VIRT_MACHINE  MACHINE_TYPE_NAME("virt")