hw/acpi: Update ACPI GED framework to support vCPU Hotplug

ACPI GED (as described in the ACPI 6.4 spec) uses an interrupt listed in the
_CRS object of GED to intimate OSPM about an event. Later then demultiplexes the
notified event by evaluating ACPI _EVT method to know the type of event. Use
ACPI GED to also notify the guest kernel about any CPU hot(un)plug events.

Note, GED interface is used by many hotplug events like memory hotplug, NVDIMM
hotplug and non-hotplug events like system power down event. Each of these can
be selected using a bit in the 32 bit GED IO interface. A bit has been reserved
for the CPU hotplug event.

ACPI CPU hotplug related initialization should only happen if ACPI_CPU_HOTPLUG
support has been enabled for particular architecture. Add cpu_hotplug_hw_init()
stub to avoid compilation break.

Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
Tested-by: Xianglai Li <lixianglai@loongson.cn>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
Tested-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Message-Id: <20240716111502.202344-4-salil.mehta@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>

docs/specs/acpi_hw_reduced_hotplug.rst

@@ -64,7 +64,8 @@ GED IO interface (4 byte access)
        0: Memory hotplug event
        1: System power down event
        2: NVDIMM hotplug event
-    3-31: Reserved
+       3: CPU hotplug event
+    4-31: Reserved
 
 **write_access:**
 

hw/acpi/acpi-cpu-hotplug-stub.c

@@ -19,6 +19,12 @@ void legacy_acpi_cpu_hotplug_init(MemoryRegion *parent, Object *owner,
     return;
 }
 
+void cpu_hotplug_hw_init(MemoryRegion *as, Object *owner,
+                         CPUHotplugState *state, hwaddr base_addr)
+{
+    return;
+}
+
 void acpi_cpu_ospm_status(CPUHotplugState *cpu_st, ACPIOSTInfoList ***list)
 {
     return;

hw/acpi/generic_event_device.c

@@ -25,6 +25,7 @@ static const uint32_t ged_supported_events[] = {
     ACPI_GED_MEM_HOTPLUG_EVT,
     ACPI_GED_PWR_DOWN_EVT,
     ACPI_GED_NVDIMM_HOTPLUG_EVT,
+    ACPI_GED_CPU_HOTPLUG_EVT,
 };
 
 /*
@@ -234,6 +235,8 @@ static void acpi_ged_device_plug_cb(HotplugHandler *hotplug_dev,
         } else {
             acpi_memory_plug_cb(hotplug_dev, &s->memhp_state, dev, errp);
         }
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
+        acpi_cpu_plug_cb(hotplug_dev, &s->cpuhp_state, dev, errp);
     } else {
         error_setg(errp, "virt: device plug request for unsupported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -248,6 +251,8 @@ static void acpi_ged_unplug_request_cb(HotplugHandler *hotplug_dev,
     if ((object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
                        !(object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)))) {
         acpi_memory_unplug_request_cb(hotplug_dev, &s->memhp_state, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
+        acpi_cpu_unplug_request_cb(hotplug_dev, &s->cpuhp_state, dev, errp);
     } else {
         error_setg(errp, "acpi: device unplug request for unsupported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -261,6 +266,8 @@ static void acpi_ged_unplug_cb(HotplugHandler *hotplug_dev,
 
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         acpi_memory_unplug_cb(&s->memhp_state, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
+        acpi_cpu_unplug_cb(&s->cpuhp_state, dev, errp);
     } else {
         error_setg(errp, "acpi: device unplug for unsupported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -272,6 +279,7 @@ static void acpi_ged_ospm_status(AcpiDeviceIf *adev, ACPIOSTInfoList ***list)
     AcpiGedState *s = ACPI_GED(adev);
 
     acpi_memory_ospm_status(&s->memhp_state, list);
+    acpi_cpu_ospm_status(&s->cpuhp_state, list);
 }
 
 static void acpi_ged_send_event(AcpiDeviceIf *adev, AcpiEventStatusBits ev)
@@ -286,6 +294,8 @@ static void acpi_ged_send_event(AcpiDeviceIf *adev, AcpiEventStatusBits ev)
         sel = ACPI_GED_PWR_DOWN_EVT;
     } else if (ev & ACPI_NVDIMM_HOTPLUG_STATUS) {
         sel = ACPI_GED_NVDIMM_HOTPLUG_EVT;
+    } else if (ev & ACPI_CPU_HOTPLUG_STATUS) {
+        sel = ACPI_GED_CPU_HOTPLUG_EVT;
     } else {
         /* Unknown event. Return without generating interrupt. */
         warn_report("GED: Unsupported event %d. No irq injected", ev);
@@ -371,6 +381,42 @@ static const VMStateDescription vmstate_acpi_ged = {
     }
 };
 
+static void acpi_ged_realize(DeviceState *dev, Error **errp)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    AcpiGedState *s = ACPI_GED(dev);
+    uint32_t ged_events;
+    int i;
+
+    ged_events = ctpop32(s->ged_event_bitmap);
+
+    for (i = 0; i < ARRAY_SIZE(ged_supported_events) && ged_events; i++) {
+        uint32_t event = s->ged_event_bitmap & ged_supported_events[i];
+
+        if (!event) {
+            continue;
+        }
+
+        switch (event) {
+        case ACPI_GED_CPU_HOTPLUG_EVT:
+            /* initialize CPU Hotplug related regions */
+            memory_region_init(&s->container_cpuhp, OBJECT(dev),
+                                "cpuhp container",
+                                ACPI_CPU_HOTPLUG_REG_LEN);
+            sysbus_init_mmio(sbd, &s->container_cpuhp);
+            cpu_hotplug_hw_init(&s->container_cpuhp, OBJECT(dev),
+                                &s->cpuhp_state, 0);
+            break;
+        }
+        ged_events--;
+    }
+
+    if (ged_events) {
+        error_report("Unsupported events specified");
+        abort();
+    }
+}
+
 static void acpi_ged_initfn(Object *obj)
 {
     DeviceState *dev = DEVICE(obj);
@@ -411,6 +457,7 @@ static void acpi_ged_class_init(ObjectClass *class, void *data)
     dc->desc = "ACPI Generic Event Device";
     device_class_set_props(dc, acpi_ged_properties);
     dc->vmsd = &vmstate_acpi_ged;
+    dc->realize = acpi_ged_realize;
 
     hc->plug = acpi_ged_device_plug_cb;
     hc->unplug_request = acpi_ged_unplug_request_cb;

include/hw/acpi/generic_event_device.h

@@ -62,6 +62,7 @@
 #include "hw/sysbus.h"
 #include "hw/acpi/memory_hotplug.h"
 #include "hw/acpi/ghes.h"
+#include "hw/acpi/cpu.h"
 #include "qom/object.h"
 
 #define ACPI_POWER_BUTTON_DEVICE "PWRB"
@@ -95,6 +96,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(AcpiGedState, ACPI_GED)
 #define ACPI_GED_MEM_HOTPLUG_EVT   0x1
 #define ACPI_GED_PWR_DOWN_EVT      0x2
 #define ACPI_GED_NVDIMM_HOTPLUG_EVT 0x4
+#define ACPI_GED_CPU_HOTPLUG_EVT    0x8
 
 typedef struct GEDState {
     MemoryRegion evt;
@@ -106,6 +108,8 @@ struct AcpiGedState {
     SysBusDevice parent_obj;
     MemHotplugState memhp_state;
     MemoryRegion container_memhp;
+    CPUHotplugState cpuhp_state;
+    MemoryRegion container_cpuhp;
     GEDState ged_state;
     uint32_t ged_event_bitmap;
     qemu_irq irq;