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Re: [Qemu-devel] [RESEND PATCH v4 2/6] acpi, mem-hotplug: Add unplug req


From: Igor Mammedov
Subject: Re: [Qemu-devel] [RESEND PATCH v4 2/6] acpi, mem-hotplug: Add unplug request cb for memory device
Date: Mon, 16 Mar 2015 14:53:23 +0100

On Mon, 16 Mar 2015 16:58:14 +0800
Zhu Guihua <address@hidden> wrote:

> From: Tang Chen <address@hidden>
> 
> 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 <address@hidden>
> Signed-off-by: Zhu Guihua <address@hidden>
'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) \




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