Re: [PATCH v4 6/6] hw/loongarch/virt: Enable cpu hotplug feature on virt machine

[bibo mao <maobibo@loongson.cn>]

On 2024/11/22 下午9:50, Igor Mammedov wrote:
> On Tue, 19 Nov 2024 18:18:27 +0800
> bibo mao <maobibo@loongson.cn> wrote:
> 
>> On 2024/11/19 上午1:03, Igor Mammedov wrote:
>>> On Tue, 12 Nov 2024 10:17:38 +0800
>>> Bibo Mao <maobibo@loongson.cn> wrote:
>>>    
>>>> On virt machine, enable CPU hotplug feature has_hotpluggable_cpus. For
>>>> hot-added CPUs, there is socket-id/core-id/thread-id property set,
>>>> arch_id can be caculated from these properties. So that cpu slot can be
>>>> searched from its arch_id.
>>>>
>>>> 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 | 68 +++++++++++++++++++++++++++++++++++++++------
>>>>    1 file changed, 59 insertions(+), 9 deletions(-)
>>>>
>>>> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
>>>> index b49b15c0f6..5f81673368 100644
>>>> --- a/hw/loongarch/virt.c
>>>> +++ b/hw/loongarch/virt.c
>>>> @@ -890,7 +890,7 @@ 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;
>>>>    
>>>> @@ -905,7 +905,7 @@ 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);
>>>>        }
>>>> @@ -1369,11 +1369,15 @@ static void virt_get_topo_from_index(MachineState *ms,
>>>>    }
>>>>    
>>>>    /* Find cpu slot in machine->possible_cpus by arch_id */
>>>> -static CPUArchId *virt_find_cpu_slot(MachineState *ms, int arch_id)
>>>> +static CPUArchId *virt_find_cpu_slot(MachineState *ms, int arch_id, int *index)
>>>>    {
>>>>        int n;
>>>>        for (n = 0; n < ms->possible_cpus->len; n++) {
>>>>            if (ms->possible_cpus->cpus[n].arch_id == arch_id) {
>>>> +            if (index) {
>>>> +                *index = n;
>>>> +            }
>>>> +
>>>>                return &ms->possible_cpus->cpus[n];
>>>>            }
>>>>        }
>>>> @@ -1386,10 +1390,12 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
>>>>    {
>>>>        LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
>>>>        MachineState *ms = MACHINE(OBJECT(hotplug_dev));
>>>> +    CPUState *cs = CPU(dev);
>>>>        LoongArchCPU *cpu = LOONGARCH_CPU(dev);
>>>>        CPUArchId *cpu_slot;
>>>>        Error *local_err = NULL;
>>>> -    int arch_id;
>>>> +    LoongArchCPUTopo topo;
>>>> +    int arch_id, index;
>>>>    
>>>>        /* sanity check the cpu */
>>>>        if (!object_dynamic_cast(OBJECT(cpu), ms->cpu_type)) {
>>>> @@ -1408,12 +1414,45 @@ 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;
>>>> +        cs->cpu_index = index;
>>> this whole branch applies to cold-plugged CPUs as well, especially
>>> if both (hot/cold plugged CPUs are getting wired with help of pre_plug)
>>> So this hunk should be introduced somewhere earlier in series,
>>> and than I'd likely won't need (cpu->phy_id == UNSET_PHY_ID) check to begin with.
>>>
>>> the only difference vs cold-plug would be need to call acpi_ged plug handler,
>>> like you are dong below in virt_cpu_plug
>> Sure, will check acpi_ged plug handler for cold-plug/hot-plug CPU.
>>
>>>    
>>>>        } else {
>>>>            /* For cold-add cpu, find cpu slot from arch_id */
>>>>            arch_id = cpu->phy_id;
>>>> -        cpu_slot = virt_find_cpu_slot(ms, arch_id);
>>>> +        cpu_slot = virt_find_cpu_slot(ms, arch_id, NULL);
>>>>        }
>>>>    
>>>>        numa_cpu_pre_plug(cpu_slot, dev, &local_err);
>>>> @@ -1468,7 +1507,7 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev,
>>>>            return;
>>>>        }
>>>>    
>>>> -    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
>>>> +    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id, NULL);
>>>>        cpu_slot->cpu = NULL;
>>>>        return;
>>>>    }
>>>> @@ -1477,14 +1516,24 @@ 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);
>>>>    
>>>>        /* Connect irq to cpu, including ipi and extioi irqchip */
>>>>        virt_init_cpu_irq(ms, CPU(cpu));
>>>> -    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
>>>> +    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id, NULL);
>>>>        cpu_slot->cpu = CPU(dev);
>>>> +
>>>> +    if (lvms->acpi_ged) {
>>> Why do you need check, can machine be created without acpi_ged?
>> There is no NULL check with macro HOTPLUG_HANDLER() for cold-plug cpu.
>> Now machine is created with acpi_ged always, in later will add noapic
>> option support.
> 
> you've probably meant '-noacpi',
> anyways right now acpi_ged is always present, so make this patch unconditional.
Sure, will do in this way.

Regards
Bibo Mao
> 
> If later on you find a use-case for '-noacpi' and add it,
> then introduce condition at that time.
> 
>>
>> Regards
>> Bibo Mao
>>
>>>    
>>>> +        hotplug_handler_plug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &local_err);
>>>> +        if (local_err) {
>>>> +            error_propagate(errp, local_err);
>>>> +            return;
>>>> +        }
>>>> +    }
>>>> +
>>>>        return;
>>>>    }
>>>>    
>>>> @@ -1667,6 +1716,7 @@ 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;
>>