[Qemu-devel] [PATCH Part2 12/13] acpi: Add hardware implementation for memory hot unplug.

[Tang Chen]

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 <address@hidden>
Signed-off-by: Tang Chen <address@hidden>
---
 docs/specs/acpi_mem_hotplug.txt |  8 ++++++--
 hw/acpi/memory_hotplug.c        | 23 ++++++++++++++++++++---
 hw/core/qdev.c                  |  2 +-
 include/hw/qdev-core.h          |  1 +
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/docs/specs/acpi_mem_hotplug.txt b/docs/specs/acpi_mem_hotplug.txt
index 1290994..28a1ffa 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 indicate that device is being
+                removed.
+              3-7: reserved and should be ignored by OSPM
       [0x15-0x17] reserved
 
   write access:
@@ -35,7 +37,9 @@ 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: set by hardware after it has emitted device eject event for
+                selected memory device
+              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 2b0c8ca..b9e8752 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;
@@ -121,21 +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 */
+            /*
+             * QEmu memory hot unplug is an asynchronized 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;
     }
-
 }
 static const MemoryRegionOps acpi_memory_hotplug_ops = {
     .read = acpi_memory_hotplug_read,
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 413b413..12a3557 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -223,7 +223,7 @@ void qdev_set_legacy_instance_id(DeviceState *dev, int 
alias_id,
     dev->alias_required_for_version = required_for_version;
 }
 
-static HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
+HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
 {
     HotplugHandler *hotplug_ctrl = NULL;
 
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index d3a2940..128fcfc 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -261,6 +261,7 @@ void qdev_init_nofail(DeviceState *dev);
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version);
 void qdev_unplug(DeviceState *dev, Error **errp);
+HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev);
 void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
                                   DeviceState *dev, Error **errp);
 void qdev_machine_creation_done(void);
-- 
1.8.4.2