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

[Igor Mammedov <imammedo@redhat.com>]

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;  
>