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;
     } 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) {
+        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;
-- 
2.39.3

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

>      } 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?

> +        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;

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.

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;

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.

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;  
>