Re: [Qemu-devel] [PATCH v3 10/10] acpi: Add hardware implementation for memory hot unplug.

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Feb 26, 2015 at 09:16:52AM +0800, Zhu Guihua wrote:
> From: Tang Chen <tangchen@cn.fujitsu.com>
> 
> This patch adds a new bit to memory hotplug IO port indicating that
> ej0 has been evaluated by guest OS. And call pc-dimm unplug cb to do
> the real removal.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
> Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>

so previous patch adds _EJ0 but no real hardware to
back it up. It's bad for bisect and is not making
review easier.


> ---
>  docs/specs/acpi_mem_hotplug.txt   | 11 +++++++++--
>  hw/acpi/memory_hotplug.c          | 24 ++++++++++++++++++++++--
>  hw/i386/acpi-dsdt-mem-hotplug.dsl | 11 ++++++++++-
>  include/hw/acpi/pc-hotplug.h      |  1 +
>  trace-events                      |  1 +
>  5 files changed, 43 insertions(+), 5 deletions(-)
> 
> diff --git a/docs/specs/acpi_mem_hotplug.txt b/docs/specs/acpi_mem_hotplug.txt
> index 1290994..85cd4b8 100644
> --- a/docs/specs/acpi_mem_hotplug.txt
> +++ b/docs/specs/acpi_mem_hotplug.txt
> @@ -19,7 +19,9 @@ Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access):
>                1: Device insert event, used to distinguish device for which
>                   no device check event to OSPM was issued.
>                   It's valid only when bit 1 is set.
> -              2-7: reserved and should be ignored by OSPM
> +              2: Device remove event, used to distinguish device for which
> +                 no device check event to OSPM was issued.
> +              3-7: reserved and should be ignored by OSPM
>        [0x15-0x17] reserved
>  
>    write access:
> @@ -35,7 +37,12 @@ Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access):
>                1: if set to 1 clears device insert event, set by OSPM
>                   after it has emitted device check event for the
>                   selected memory device
> -              2-7: reserved, OSPM must clear them before writing to register
> +              2: if set to 1 clears device remove event, set by OSPM
> +                 after it has emitted device check event for the
> +                 selected memory device. if guest fails to eject device, it
> +                 should send OST event about it and forget about device
> +                 removal.
> +              3-7: reserved, OSPM must clear them before writing to register
>  
>  Selecting memory device slot beyond present range has no effect on platform:
>     - write accesses to memory hot-plug registers not documented above are
> diff --git a/hw/acpi/memory_hotplug.c b/hw/acpi/memory_hotplug.c
> index ffacecf..64c7b33 100644
> --- a/hw/acpi/memory_hotplug.c
> +++ b/hw/acpi/memory_hotplug.c
> @@ -2,6 +2,7 @@
>  #include "hw/acpi/pc-hotplug.h"
>  #include "hw/mem/pc-dimm.h"
>  #include "hw/boards.h"
> +#include "hw/qdev-core.h"
>  #include "trace.h"
>  #include "qapi-event.h"
>  
> @@ -75,6 +76,7 @@ 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:
> @@ -90,6 +92,8 @@ static void acpi_memory_hotplug_write(void *opaque, hwaddr addr, uint64_t data,
>      MemHotplugState *mem_st = opaque;
>      MemStatus *mdev;
>      ACPIOSTInfo *info;
> +    DeviceState *dev = NULL;
> +    HotplugHandler *hotplug_ctrl = NULL;
>  
>      if (!mem_st->dev_count) {
>          return;
> @@ -121,18 +125,34 @@ static void acpi_memory_hotplug_write(void *opaque, hwaddr addr, uint64_t data,
>          mdev = &mem_st->devs[mem_st->selector];
>          mdev->ost_status = data;
>          trace_mhp_acpi_write_ost_status(mem_st->selector, mdev->ost_status);
> -        /* TODO: implement memory removal on guest signal */
>  
>          info = acpi_memory_device_status(mem_st->selector, mdev);
>          qapi_event_send_acpi_device_ost(info, &error_abort);
>          qapi_free_ACPIOSTInfo(info);
>          break;
> -    case 0x14:
> +    case 0x14: /* set is_* fields */
>          mdev = &mem_st->devs[mem_st->selector];
> +
>          if (data & 2) { /* clear insert event */
>              mdev->is_inserting  = false;
>              trace_mhp_acpi_clear_insert_evt(mem_st->selector);
> +        } else if (data & 4) { /* request removal of device */
> +            mdev->is_removing = false;
> +            trace_mhp_acpi_clear_remove_evt(mem_st->selector);
> +            /*
> +             * QEMU memory hot unplug is an asynchronous procedure. QEMU first
> +             * calls pc-dimm unplug request cb to send a SCI to guest. When the
> +             * Guest OS finished handling the SCI, it evaluates ACPI EJ0, and
> +             * QEMU calls pc-dimm unplug cb to remove memory device.
> +             */
> +            dev = DEVICE(mdev->dimm);
> +            hotplug_ctrl = qdev_get_hotplug_handler(dev);
> +            /* Call pc-dimm unplug cb. */
> +            hotplug_handler_unplug(hotplug_ctrl, dev, NULL);
>          }
> +
> +        break;
> +    default:
>          break;
>      }
>  
> diff --git a/hw/i386/acpi-dsdt-mem-hotplug.dsl b/hw/i386/acpi-dsdt-mem-hotplug.dsl
> index 2a36c47..b53bf77 100644
> --- a/hw/i386/acpi-dsdt-mem-hotplug.dsl
> +++ b/hw/i386/acpi-dsdt-mem-hotplug.dsl
> @@ -50,6 +50,7 @@
>                  Offset(20),
>                  MEMORY_SLOT_ENABLED,  1, // 1 if enabled, read only
>                  MEMORY_SLOT_INSERT_EVENT, 1, // (read) 1 if has a insert event. (write) 1 to clear event
> +                MEMORY_SLOT_REMOVE_EVENT, 1, // (read) 1 if has a remove event. (write) 1 to clear event
>              }
>  
>              Mutex (MEMORY_SLOT_LOCK, 0)
> @@ -71,8 +72,9 @@
>                      If (LEqual(MEMORY_SLOT_INSERT_EVENT, One)) { // Memory device needs check
>                          MEMORY_SLOT_NOTIFY_METHOD(Local0, 1)
>                          Store(1, MEMORY_SLOT_INSERT_EVENT)
> +                    } Elseif (LEqual(MEMORY_SLOT_REMOVE_EVENT, One)) { // Ejection request
> +                        MEMORY_SLOT_NOTIFY_METHOD(Local0, 3)
>                      }
> -                    // TODO: handle memory eject request
>                      Add(Local0, One, Local0) // goto next DIMM
>                  }
>                  Release(MEMORY_SLOT_LOCK)
> @@ -172,5 +174,12 @@
>                  Store(Arg2, MEMORY_SLOT_OST_STATUS)
>                  Release(MEMORY_SLOT_LOCK)
>              }
> +
> +            Method(MEMORY_SLOT_EJECT_METHOD, 2) {
> +                Acquire(MEMORY_SLOT_LOCK, 0xFFFF)
> +                Store(ToInteger(Arg0), MEMORY_SLOT_SLECTOR) // select DIMM
> +                Store(One, MEMORY_SLOT_REMOVE_EVENT)
> +                Release(MEMORY_SLOT_LOCK)
> +            }
>          } // Device()
>      } // Scope()
> diff --git a/include/hw/acpi/pc-hotplug.h b/include/hw/acpi/pc-hotplug.h
> index ae30ff1..b61b6ea 100644
> --- a/include/hw/acpi/pc-hotplug.h
> +++ b/include/hw/acpi/pc-hotplug.h
> @@ -42,6 +42,7 @@
>  #define MEMORY_SLOT_PROXIMITY        MPX
>  #define MEMORY_SLOT_ENABLED          MES
>  #define MEMORY_SLOT_INSERT_EVENT     MINS
> +#define MEMORY_SLOT_REMOVE_EVENT     MRMV
>  #define MEMORY_SLOT_SLECTOR          MSEL
>  #define MEMORY_SLOT_OST_EVENT        MOEV
>  #define MEMORY_SLOT_OST_STATUS       MOSC
> diff --git a/trace-events b/trace-events
> index f87b077..4439f45 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -1568,6 +1568,7 @@ mhp_acpi_write_slot(uint32_t slot) "set active slot: 0x%"PRIx32
>  mhp_acpi_write_ost_ev(uint32_t slot, uint32_t ev) "slot[0x%"PRIx32"] OST EVENT: 0x%"PRIx32
>  mhp_acpi_write_ost_status(uint32_t slot, uint32_t st) "slot[0x%"PRIx32"] OST STATUS: 0x%"PRIx32
>  mhp_acpi_clear_insert_evt(uint32_t slot) "slot[0x%"PRIx32"] clear insert event"
> +mhp_acpi_clear_remove_evt(uint32_t slot) "slot[0x%"PRIx32"] clear remove event"
>  
>  # hw/i386/pc.c
>  mhp_pc_dimm_assigned_slot(int slot) "0x%d"
> -- 
> 1.9.3