[RESEND,v4,2/6] acpi, mem-hotplug: Add unplug request cb for memory device

From: Tang Chen <tangchen@cn.fujitsu.com>

Memory hot unplug are both asynchronous procedures.
When the unplug operation happens, unplug request cb is called first.
And when guest OS finished handling unplug, unplug cb will be called
to do the real removal of device.

This patch adds unplug request cb for memory device, and adds the
is_removing boolean field to MemStatus. This field is used to indicate
whether the memory slot is being removed. This field is set to true in
acpi_memory_unplug_request_cb().

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>
---
 hw/acpi/ich9.c                   | 10 ++++++++--
 hw/acpi/memory_hotplug.c         | 19 +++++++++++++++++++
 hw/acpi/piix4.c                  |  6 +++++-
 include/hw/acpi/memory_hotplug.h |  4 ++++
 4 files changed, 36 insertions(+), 3 deletions(-)

On Mon, 16 Mar 2015 16:58:14 +0800
Zhu Guihua <zhugh.fnst@cn.fujitsu.com> wrote:

> From: Tang Chen <tangchen@cn.fujitsu.com>
> 
> Memory hot unplug are both asynchronous procedures.
> When the unplug operation happens, unplug request cb is called first.
> And when guest OS finished handling unplug, unplug cb will be called
> to do the real removal of device.
Since unplug is rather complicated multi-stage process,
it's worth to describe in in acpi_mem_hotplug.txt rather then put it
in commit message here. Preferably with process flow diagram.


> 
> This patch adds unplug request cb for memory device, and adds the
> is_removing boolean field to MemStatus. This field is used to indicate
> whether the memory slot is being removed. This field is set to true in
> acpi_memory_unplug_request_cb().
> 
> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
> Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>
'is_removing' field is introduced here without associated
documentation about how it's used and then in 6/6 it's usage is extended
and some docs are added.

Perhaps it would be better to put documentation patch here or as
a separate one before this patch so that reviewers would know
intended use of new fields that are added here in advance.

Also documentation in 6/6 is not complete. It adds 'removing' event
description but it doesn't amend following text with unplug part:

"ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add
events."


> ---
>  hw/acpi/ich9.c                   | 10 ++++++++--
>  hw/acpi/memory_hotplug.c         | 19 +++++++++++++++++++
>  hw/acpi/piix4.c                  |  6 +++++-
>  include/hw/acpi/memory_hotplug.h |  4 ++++
>  4 files changed, 36 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
> index 5352e19..b85eed4 100644
> --- a/hw/acpi/ich9.c
> +++ b/hw/acpi/ich9.c
> @@ -400,8 +400,14 @@ void ich9_pm_device_plug_cb(ICH9LPCPMRegs *pm, DeviceState *dev, Error **errp)
>  void ich9_pm_device_unplug_request_cb(ICH9LPCPMRegs *pm, DeviceState *dev,
>                                        Error **errp)
>  {
> -    error_setg(errp, "acpi: device unplug request for not supported device"
> -               " type: %s", object_get_typename(OBJECT(dev)));
> +    if (pm->acpi_memory_hotplug.is_enabled &&
> +        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        acpi_memory_unplug_request_cb(&pm->acpi_regs, pm->irq,
> +                                      &pm->acpi_memory_hotplug, dev, errp);
> +    } else {
> +        error_setg(errp, "acpi: device unplug request for not supported device"
> +                   " type: %s", object_get_typename(OBJECT(dev)));
> +    }
>  }
>  
>  void ich9_pm_device_unplug_cb(ICH9LPCPMRegs *pm, DeviceState *dev,
> diff --git a/hw/acpi/memory_hotplug.c b/hw/acpi/memory_hotplug.c
> index 0efc357..2ef6a94 100644
> --- a/hw/acpi/memory_hotplug.c
> +++ b/hw/acpi/memory_hotplug.c
> @@ -75,6 +75,7 @@ static uint64_t acpi_memory_hotplug_read(void *opaque, hwaddr addr,
>      case 0x14: /* pack and return is_* fields */
>          val |= mdev->is_enabled   ? 1 : 0;
>          val |= mdev->is_inserting ? 2 : 0;
> +        val |= mdev->is_removing  ? 4 : 0;
>          trace_mhp_acpi_read_flags(mem_st->selector, val);
>          break;
>      default:
> @@ -208,6 +209,24 @@ void acpi_memory_plug_cb(ACPIREGS *ar, qemu_irq irq, MemHotplugState *mem_st,
>      return;
>  }
>  
> +void acpi_memory_unplug_request_cb(ACPIREGS *ar, qemu_irq irq,
> +                                   MemHotplugState *mem_st,
> +                                   DeviceState *dev, Error **errp)
> +{
> +    MemStatus *mdev;
> +
> +    mdev = acpi_memory_slot_status(mem_st, dev, errp);
> +    if (!mdev) {
> +        return;
> +    }
> +
> +    mdev->is_removing = true;
> +
> +    /* Do ACPI magic */
> +    ar->gpe.sts[0] |= ACPI_MEMORY_HOTPLUG_STATUS;
> +    acpi_update_sci(ar, irq);
> +}
> +
>  static const VMStateDescription vmstate_memhp_sts = {
>      .name = "memory hotplug device state",
>      .version_id = 1,
> diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
> index d1f1179..f716e91 100644
> --- a/hw/acpi/piix4.c
> +++ b/hw/acpi/piix4.c
> @@ -361,7 +361,11 @@ static void piix4_device_unplug_request_cb(HotplugHandler *hotplug_dev,
>  {
>      PIIX4PMState *s = PIIX4_PM(hotplug_dev);
>  
> -    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> +    if (s->acpi_memory_hotplug.is_enabled &&
> +        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        acpi_memory_unplug_request_cb(&s->ar, s->irq, &s->acpi_memory_hotplug,
> +                                      dev, errp);
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
>          acpi_pcihp_device_unplug_cb(&s->ar, s->irq, &s->acpi_pci_hotplug, dev,
>                                      errp);
>      } else {
> diff --git a/include/hw/acpi/memory_hotplug.h b/include/hw/acpi/memory_hotplug.h
> index 7bbf8a0..c437a85 100644
> --- a/include/hw/acpi/memory_hotplug.h
> +++ b/include/hw/acpi/memory_hotplug.h
> @@ -11,6 +11,7 @@ typedef struct MemStatus {
>      DeviceState *dimm;
>      bool is_enabled;
>      bool is_inserting;
> +    bool is_removing;
>      uint32_t ost_event;
>      uint32_t ost_status;
>  } MemStatus;
> @@ -28,6 +29,9 @@ void acpi_memory_hotplug_init(MemoryRegion *as, Object *owner,
>  
>  void acpi_memory_plug_cb(ACPIREGS *ar, qemu_irq irq, MemHotplugState *mem_st,
>                           DeviceState *dev, Error **errp);
> +void acpi_memory_unplug_request_cb(ACPIREGS *ar, qemu_irq irq,
> +                                   MemHotplugState *mem_st,
> +                                   DeviceState *dev, Error **errp);
>  
>  extern const VMStateDescription vmstate_memory_hotplug;
>  #define VMSTATE_MEMORY_HOTPLUG(memhp, state) \