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

[Zhu Guihua]

From: Tang Chen <address@hidden>

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>
Signed-off-by: Zhu Guihua <address@hidden>
---
 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