On virt machine, enable cpu hotplug feature has_hotpluggable_cpus.
For hot-added cpu 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         | 68 ++++++++++++++++++++++++++++++++++---
 include/hw/loongarch/virt.h |  2 ++
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 655312b0fe..cecb12786b 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -851,8 +851,9 @@ 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,
@@ -877,11 +878,12 @@ 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)) {
@@ -1382,8 +1384,40 @@ 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 non hot-add cpu, topo property is not set. And only physical id
@@ -1465,8 +1499,33 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
                                 DeviceState *dev, Error **errp)
 {
     CPUArchId *cpu_slot;
+    Error *local_err = NULL;
     LoongArchCPU *cpu = LOONGARCH_CPU(dev);
+    CPUState *cs = CPU(cpu);
+    CPULoongArchState *env;
     LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
+    int pin;
+
+    if (lvms->acpi_ged) {
+        env = &(cpu->env);
+        env->address_space_iocsr = &lvms->as_iocsr;
+
+        /* connect ipi irq to cpu irq, logic cpu index used here */
+        qdev_connect_gpio_out(lvms->ipi, cs->cpu_index,
+                              qdev_get_gpio_in(dev, IRQ_IPI));
+        env->ipistate = lvms->ipi;
+
+        for (pin = 0; pin < LS3A_INTC_IP; pin++) {
+            qdev_connect_gpio_out(lvms->extioi, (cs->cpu_index * 8 + pin),
+                                  qdev_get_gpio_in(dev, pin + 2));
+        }
+
+        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(MACHINE(lvms), cpu->phy_id, NULL);
     cpu_slot->cpu = CPU(dev);
@@ -1652,6 +1711,7 @@ 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")
-- 
2.39.3

[snip]

> @@ -1382,8 +1384,40 @@ 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 {

Here you allow user to specify topology IDs, but "else" still indicates
user could use "phy_id" instead of topology IDs, right?

Is it necessary to expose "phy_id" to user?

Thanks,
Zhao

On 2024/10/29 下午9:48, Zhao Liu wrote:
> [snip]
> 
>> @@ -1382,8 +1384,40 @@ 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 {
> 
> Here you allow user to specify topology IDs, but "else" still indicates
> user could use "phy_id" instead of topology IDs, right?
"else" for cold-plug CPUs which is created with index from [0 -- smp.cpus)

> 
> Is it necessary to expose "phy_id" to user?
We will remove phy_id property and unexpose it to user.

Regards
Bibo Mao
> 
> Thanks,
> Zhao
> 

> > > @@ -1382,8 +1384,40 @@ 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 {
> > 
> > Here you allow user to specify topology IDs, but "else" still indicates
> > user could use "phy_id" instead of topology IDs, right?
> "else" for cold-plug CPUs which is created with index from [0 -- smp.cpus)
> 
> > 
> > Is it necessary to expose "phy_id" to user?
> We will remove phy_id property and unexpose it to user.
> 

Thanks! The issue lies with the property itself. Even if you try to
support a hotplug scheme based on topology IDs, users can actually use
phy_id for hotplugging. Removing it seems fine.

Regards,
Zhao