Re: [Qemu-devel] [PATCH v4 4/8] hw/arm/virt: Add memory hotplug framework

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 9 Apr 2019 11:29:31 +0100
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:

> From: Eric Auger <eric.auger@redhat.com>
> 
> This patch adds the memory hot-plug/hot-unplug infrastructure
> in machvirt. The device memory is not yet exposed to the Guest
> either though DT or ACPI and hence both cold/hot plug of memory
s/though/through/

> is explicitly disabled for now.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Kwangwoo Lee <kwangwoo.lee@sk.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
>  default-configs/arm-softmmu.mak |  3 +++
>  hw/arm/virt.c                   | 45 ++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/default-configs/arm-softmmu.mak b/default-configs/arm-softmmu.mak
> index 613d19a..9f4b803 100644
> --- a/default-configs/arm-softmmu.mak
> +++ b/default-configs/arm-softmmu.mak
> @@ -160,3 +160,6 @@ CONFIG_MUSICPAL=y
>  
>  # for realview and versatilepb
>  CONFIG_LSI_SCSI_PCI=y
> +
> +CONFIG_MEM_DEVICE=y
> +CONFIG_DIMM=y
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index ce2664a..da516b3 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -61,6 +61,8 @@
>  #include "hw/arm/smmuv3.h"
>  #include "hw/acpi/acpi.h"
>  #include "target/arm/internals.h"
> +#include "hw/mem/pc-dimm.h"
> +#include "hw/mem/nvdimm.h"
>  
>  #define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \
>      static void virt_##major##_##minor##_class_init(ObjectClass *oc, \
> @@ -1806,6 +1808,34 @@ static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
>      return ms->possible_cpus;
>  }
>  
> +static void virt_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> +                                 Error **errp)
> +{
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        error_setg(errp, "memory cold/hot plug is not yet supported");
> +        return;
> +    }
add comment here why it's needed.

> +
> +    pc_dimm_pre_plug(PC_DIMM(dev), MACHINE(hotplug_dev), NULL, errp);
maybe before calling this there probably should be check if acpi is enabled.

not sure if arm/virt board honors -no-acpi CLI option.

> +}
> +
> +static void virt_memory_plug(HotplugHandler *hotplug_dev,
> +                             DeviceState *dev, Error **errp)
> +{
> +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> +
> +    pc_dimm_plug(PC_DIMM(dev), MACHINE(vms), NULL);
> +
> +}
> +
> +static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
> +                                            DeviceState *dev, Error **errp)
> +{
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        virt_memory_pre_plug(hotplug_dev, dev, errp);
> +    }
> +}
> +
>  static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
>                                          DeviceState *dev, Error **errp)
>  {
> @@ -1817,12 +1847,23 @@ static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
>                                       SYS_BUS_DEVICE(dev));
>          }
>      }
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        virt_memory_plug(hotplug_dev, dev, errp);
> +    }
> +}
> +
> +static void virt_machine_device_unplug_request_cb(HotplugHandler *hotplug_dev,
> +                                          DeviceState *dev, Error **errp)
> +{
> +    error_setg(errp, "device unplug request for unsupported device"
> +               " type: %s", object_get_typename(OBJECT(dev)));
>  }
>  
>  static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
>                                                          DeviceState *dev)
>  {
> -    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE) ||
> +       (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM))) {
>          return HOTPLUG_HANDLER(machine);
>      }
>  
> @@ -1886,7 +1927,9 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
>      mc->kvm_type = virt_kvm_type;
>      assert(!mc->get_hotplug_handler);
>      mc->get_hotplug_handler = virt_machine_get_hotplug_handler;
> +    hc->pre_plug = virt_machine_device_pre_plug_cb;
>      hc->plug = virt_machine_device_plug_cb;
> +    hc->unplug_request = virt_machine_device_unplug_request_cb;
>  }
>  
>  static void virt_instance_init(Object *obj)