[Qemu-devel] [PATCH 3/6] s390: sclp event support

[Christian Borntraeger]

From: Heinz Graalfs <address@hidden>

Several SCLP features are considered to be events. Those events don't
provide SCLP commands on their own, instead they are all based on
Read Event Data, Write Event Data, Write Event Mask and the service
interrupt. Follow-on patches will provide SCLP's Signal Quiesce (via
system_powerdown) and the ASCII console.
Further down the road the sclp line mode console and configuration
change events (e.g. cpu hotplug) can be implemented.

Signed-off-by: Heinz Graalfs <address@hidden>
Signed-off-by: Christian Borntraeger <address@hidden>
---
 hw/s390-event-facility.c |  412 ++++++++++++++++++++++++++++++++++++++++++++++
 hw/s390-event-facility.h |  107 ++++++++++++
 hw/s390-sclp.c           |   49 +++++-
 hw/s390-sclp.h           |   43 +++++
 hw/s390x/Makefile.objs   |    2 +-
 5 files changed, 606 insertions(+), 7 deletions(-)
 create mode 100644 hw/s390-event-facility.c
 create mode 100644 hw/s390-event-facility.h

diff --git a/hw/s390-event-facility.c b/hw/s390-event-facility.c
new file mode 100644
index 0000000..42ac102
--- /dev/null
+++ b/hw/s390-event-facility.c
@@ -0,0 +1,412 @@
+/*
+ * SCLP
+ *    Event Facility
+ *       handles SCLP event types
+ *          - Signal Quiesce - system power down
+ *          - ASCII Console Data - VT220 read and write
+ *
+ * Copyright IBM, Corp. 2007, 2012
+ *
+ * Authors:
+ *  Heinz Graalfs <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "monitor.h"
+#include "sysemu.h"
+
+#include "s390-sclp.h"
+#include "s390-event-facility.h"
+
+typedef struct EventTypes {
+    BusState qbus;
+    SCLPEventFacility *event_facility;
+} EventTypes;
+
+struct SCLPEventFacility {
+    EventTypes sbus;
+    DeviceState *qdev;
+    /* guest' receive mask */
+    unsigned int receive_mask;
+};
+
+/* return true if any child has event pending set */
+static bool event_pending(void)
+{
+    BusChild *kid;
+    SCLPEvent *event;
+
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    QTAILQ_FOREACH(kid, &event_facility->sbus.qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        event = DO_UPCAST(SCLPEvent, qdev, qdev);
+        lock(event);
+        if (event->event_pending) {
+            unlock(event);
+            return true;
+        }
+        unlock(event);
+    }
+    return false;
+}
+
+static unsigned int get_host_send_mask(void)
+{
+    unsigned int mask;
+    BusChild *kid;
+    SCLPEventClass *child;
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    mask = 0;
+
+    QTAILQ_FOREACH(kid, &event_facility->sbus.qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        child = SCLP_EVENT_GET_CLASS((SCLPEvent *) qdev);
+        mask |= child->get_send_mask();
+    }
+    return mask;
+}
+
+static unsigned int get_host_receive_mask(void)
+{
+    unsigned int mask;
+    BusChild *kid;
+    SCLPEventClass *child;
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    mask = 0;
+
+    QTAILQ_FOREACH(kid, &event_facility->sbus.qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        child = SCLP_EVENT_GET_CLASS((SCLPEvent *) qdev);
+        mask |= child->get_receive_mask();
+    }
+    return mask;
+}
+
+static inline void set_guest_receive_mask(unsigned int mask)
+{
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    event_facility->receive_mask = mask;
+}
+
+static inline unsigned int get_guest_receive_mask(void)
+{
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    return event_facility->receive_mask;
+}
+
+static int check_sccb_events(SCCB *sccb)
+{
+    int slen;
+    unsigned elen = 0;
+    EventBufferHeader *event;
+    WriteEventData *wed = (WriteEventData *) sccb;
+
+    event = (EventBufferHeader *) &wed->ebh;
+    for (slen = be16_to_cpu(sccb->h.length) - sizeof(sccb->h);
+         slen > 0; slen -= elen) {
+        elen = be16_to_cpu(event->length);
+        if (elen < sizeof(*event) || elen > slen) {
+            sccb->h.response_code =
+                    cpu_to_be16(SCLP_RC_EVENT_BUFFER_SYNTAX_ERROR);
+            return 1;
+        }
+        event = (void *) event + elen;
+    }
+    if (slen) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INCONSISTENT_LENGTHS);
+        return 1;
+    }
+    return 0;
+}
+
+static void handle_sccb_write_events(SCCB *sccb)
+{
+    int slen;
+    unsigned elen = 0;
+    EventBufferHeader *event_buf;
+    BusChild *kid;
+    SCLPEvent *event;
+    SCLPEventClass *ec;
+
+    WriteEventData *wed = (WriteEventData *) sccb;
+
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    event_buf = &wed->ebh;
+
+    /* loop over all contained event buffers */
+    for (slen = be16_to_cpu(sccb->h.length) - sizeof(sccb->h);
+         slen > 0; slen -= elen) {
+        elen = be16_to_cpu(event_buf->length);
+
+        /* in case of a previous error mark all trailing buffers
+         * as not accepted */
+        if (sccb->h.response_code !=
+                cpu_to_be16(SCLP_RC_NORMAL_COMPLETION)) {
+            event_buf->flags &= ~(SCLP_EVENT_BUFFER_ACCEPTED);
+        } else {
+            sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
+            QTAILQ_FOREACH(kid, &event_facility->sbus.qbus.children, sibling) {
+                DeviceState *qdev = kid->child;
+                event = (SCLPEvent *) qdev;
+                ec = SCLP_EVENT_GET_CLASS(event);
+
+                if (ec->write_event_data &&
+                    ec->event_type() == event_buf->type) {
+                    sccb->h.response_code = cpu_to_be16(
+                            ec->write_event_data(event, event_buf));
+                    break;
+                }
+            }
+        }
+        event_buf = (void *) event_buf + elen;
+    }
+}
+
+static int write_event_data(SCCB *sccb)
+{
+    if (sccb->h.function_code != SCLP_FC_NORMAL_WRITE) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
+        goto out;
+    }
+    if (be16_to_cpu(sccb->h.length) < 8) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+        goto out;
+    }
+    /* first check the sum of all events */
+    if (check_sccb_events(sccb)) {
+        goto out;
+    }
+    /* then execute */
+    sccb->h.response_code = cpu_to_be16(SCLP_RC_NORMAL_COMPLETION);
+    handle_sccb_write_events(sccb);
+
+out:
+    return 0;
+}
+
+static void handle_sccb_read_events(SCCB *sccb, unsigned int mask)
+{
+    int slen;
+    unsigned elen = 0;
+    BusChild *kid;
+    SCLPEvent *event;
+    SCLPEventClass *ec;
+    EventBufferHeader *event_buf;
+    ReadEventData *red = (ReadEventData *) sccb;
+
+    SCLPEventFacility *event_facility = sclp_bus->event_facility->instance;
+
+    event_buf = &red->ebh;
+    event_buf->length = 0;
+    slen = sizeof(sccb->data);
+    QTAILQ_FOREACH(kid, &event_facility->sbus.qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        event = (SCLPEvent *) qdev;
+        ec = SCLP_EVENT_GET_CLASS(event);
+
+        if (mask & ec->get_send_mask()) {
+            if (ec->read_event_data(event, event_buf, &slen)) {
+                sccb->h.response_code = cpu_to_be16(SCLP_RC_NORMAL_COMPLETION);
+            }
+        }
+        elen = be16_to_cpu(event_buf->length);
+        event_buf = (void *) event_buf + elen;
+    }
+
+    if (sccb->h.control_mask[2] & SCLP_VARIABLE_LENGTH_RESPONSE) {
+        sccb->h.control_mask[2] &= ~SCLP_VARIABLE_LENGTH_RESPONSE;
+        sccb->h.length = cpu_to_be16(SCCB_SIZE - slen);
+    }
+}
+
+static int read_event_data(SCCB *sccb)
+{
+    unsigned int sclp_active_selection_mask;
+    unsigned int sclp_cp_receive_mask;
+
+    ReadEventData *red = (ReadEventData *) sccb;
+
+    if (be16_to_cpu(sccb->h.length) != SCCB_SIZE) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
+        goto out;
+    }
+
+    sclp_cp_receive_mask = get_guest_receive_mask();
+
+    /* get active selection mask */
+    switch (sccb->h.function_code) {
+    case SCLP_UNCONDITIONAL_READ:
+        sclp_active_selection_mask = sclp_cp_receive_mask;
+        break;
+    case SCLP_SELECTIVE_READ:
+        if (!(sclp_cp_receive_mask & be32_to_cpu(red->mask))) {
+            sccb->h.response_code =
+                    cpu_to_be16(SCLP_RC_INVALID_SELECTION_MASK);
+            goto out;
+        }
+        sclp_active_selection_mask = be32_to_cpu(red->mask);
+        break;
+    default:
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
+        goto out;
+    }
+
+    sccb->h.response_code = cpu_to_be16(SCLP_RC_NO_EVENT_BUFFERS_STORED);
+    handle_sccb_read_events(sccb, sclp_active_selection_mask);
+
+out:
+    return 0;
+}
+
+static int write_event_mask(SCCB *sccb)
+{
+    WriteEventMask *we_mask = (WriteEventMask *) sccb;
+
+    /* Attention: We assume that Linux uses 4-byte masks, what it actually
+       does. Architecture allows for masks of variable size, though */
+    if (be16_to_cpu(we_mask->mask_length) != 4) {
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_MASK_LENGTH);
+        goto out;
+    }
+
+    /* keep track of the guest's capability masks */
+    set_guest_receive_mask(be32_to_cpu(we_mask->cp_receive_mask));
+
+    /* return the SCLP's capability masks to the guest */
+    we_mask->send_mask = cpu_to_be32(get_host_send_mask());
+    we_mask->receive_mask = cpu_to_be32(get_host_receive_mask());
+
+    sccb->h.response_code = cpu_to_be32(SCLP_RC_NORMAL_COMPLETION);
+
+out:
+    return 0;
+}
+
+/* qemu object creation and initialization functions */
+
+#define TYPE_SCLP_EVENTS_BUS "s390-sclp-events-bus"
+#define SCLP_EVENTS_BUS(obj) OBJECT_CHECK(SCLPS390Bus, (obj),\
+                             TYPE_SCLP_EVENTS_BUS)
+
+static void sclp_events_bus_class_init(ObjectClass *klass, void *data)
+{
+}
+
+static const TypeInfo s390_sclp_events_bus_info = {
+    .name = TYPE_SCLP_EVENTS_BUS,
+    .parent = TYPE_BUS,
+    .instance_size = sizeof(SCLPS390Bus),
+    .class_init = sclp_events_bus_class_init,
+};
+
+static int command_handler(SCCB *sccb, uint64_t code)
+{
+    int r = 0;
+
+    switch (code) {
+    case SCLP_CMD_READ_EVENT_DATA:
+        r = read_event_data(sccb);
+        break;
+    case SCLP_CMD_WRITE_EVENT_DATA:
+        r = write_event_data(sccb);
+        break;
+    case SCLP_CMD_WRITE_EVENT_MASK:
+        r = write_event_mask(sccb);
+        break;
+    default:
+#ifdef DEBUG_HELPER
+        printf("KVM: invalid sclp call 0x%x / 0x%" PRIx64 "x\n", sccb, code);
+#endif
+        sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
+        break;
+    }
+    return r;
+}
+
+static int init_event_facility(S390SCLPDevice *sdev)
+{
+    SCLPEventFacility *event_facility;
+
+    event_facility = g_malloc0(sizeof(SCLPEventFacility));
+    sdev->instance = event_facility;
+    sdev->sclp_command_handler = command_handler;
+    sdev->event_pending = event_pending;
+
+    /* Spawn a new sclp-events facility */
+    qbus_create_inplace(&event_facility->sbus.qbus,
+                        TYPE_SCLP_EVENTS_BUS, (DeviceState *)sdev, NULL);
+    event_facility->sbus.qbus.allow_hotplug = 0;
+    event_facility->sbus.event_facility = event_facility;
+    event_facility->qdev = (DeviceState *) sdev;
+
+
+    return 0;
+}
+
+static void init_event_facility_class(ObjectClass *klass, void *data)
+{
+    S390SCLPDeviceClass *k = SCLP_S390_DEVICE_CLASS(klass);
+
+    k->init = init_event_facility;
+}
+
+static TypeInfo s390_sclp_event_facility_info = {
+    .name          = "s390-sclp-event-facility",
+    .parent        = TYPE_DEVICE_S390_SCLP,
+    .instance_size = sizeof(S390SCLPDevice),
+    .class_init    = init_event_facility_class,
+};
+
+static int event_qdev_init(DeviceState *qdev)
+{
+    SCLPEvent *event = DO_UPCAST(SCLPEvent, qdev, qdev);
+    SCLPEventClass *child = SCLP_EVENT_GET_CLASS(event);
+
+    return child->init(event);
+}
+
+static int event_qdev_exit(DeviceState *qdev)
+{
+    SCLPEvent *event = DO_UPCAST(SCLPEvent, qdev, qdev);
+    SCLPEventClass *child = SCLP_EVENT_GET_CLASS(event);
+    if (child->exit) {
+        child->exit(event);
+    }
+    return 0;
+}
+
+static void event_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->bus_type = TYPE_SCLP_EVENTS_BUS;
+    dc->unplug = qdev_simple_unplug_cb;
+    dc->init = event_qdev_init;
+    dc->exit = event_qdev_exit;
+}
+
+static TypeInfo s390_sclp_event_type_info = {
+    .name = TYPE_SCLP_EVENT,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(SCLPEvent),
+    .class_init = event_class_init,
+    .class_size = sizeof(SCLPEventClass),
+    .abstract = true,
+};
+
+static void register_types(void)
+{
+    type_register_static(&s390_sclp_events_bus_info);
+    type_register_static(&s390_sclp_event_facility_info);
+    type_register_static(&s390_sclp_event_type_info);
+}
+type_init(register_types)
diff --git a/hw/s390-event-facility.h b/hw/s390-event-facility.h
new file mode 100644
index 0000000..938fb4b
--- /dev/null
+++ b/hw/s390-event-facility.h
@@ -0,0 +1,107 @@
+/*
+ * SCLP
+ *    Event Facility definitions
+ *
+ * Copyright IBM, Corp. 2007, 2012
+ *
+ * Authors:
+ *  Heinz Graalfs <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef _QEMU_S390_SCLP_EVENT_FACILITY_H
+#define _QEMU_S390_SCLP_EVENT_FACILITY_H
+
+#include "qdev.h"
+#include "qemu-thread.h"
+
+/* SCLP event types */
+#define SCLP_EVENT_ASCII_CONSOLE_DATA           0x1a
+#define SCLP_EVENT_SIGNAL_QUIESCE               0x1d
+
+/* SCLP event masks */
+#define SCLP_EVENT_MASK_SIGNAL_QUIESCE          0x00000008
+#define SCLP_EVENT_MASK_MSG_ASCII               0x00000040
+
+#define SCLP_UNCONDITIONAL_READ                 0x00
+#define SCLP_SELECTIVE_READ                     0x01
+
+#define TYPE_SCLP_EVENT "s390-sclp-event-type"
+#define SCLP_EVENT(obj) \
+     OBJECT_CHECK(SCLPEvent, (obj), TYPE_SCLP_EVENT)
+#define SCLP_EVENT_CLASS(klass) \
+     OBJECT_CLASS_CHECK(SCLPEventClass, (klass), TYPE_SCLP_EVENT)
+#define SCLP_EVENT_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(SCLPEventClass, (obj), TYPE_SCLP_EVENT)
+
+typedef struct WriteEventMask {
+    SCCBHeader h;
+    uint16_t _reserved;
+    uint16_t mask_length;
+    uint32_t cp_receive_mask;
+    uint32_t cp_send_mask;
+    uint32_t send_mask;
+    uint32_t receive_mask;
+} __attribute__((packed)) WriteEventMask;
+
+typedef struct EventBufferHeader {
+    uint16_t length;
+    uint8_t  type;
+    uint8_t  flags;
+    uint16_t _reserved;
+} __attribute__((packed)) EventBufferHeader;
+
+typedef struct WriteEventData {
+    SCCBHeader h;
+    EventBufferHeader ebh;
+} __attribute__((packed)) WriteEventData;
+
+typedef struct ReadEventData {
+    SCCBHeader h;
+    EventBufferHeader ebh;
+    uint32_t mask;
+} __attribute__((packed)) ReadEventData;
+
+typedef struct SCLPEvent {
+    DeviceState qdev;
+    QemuMutex lock;
+    bool event_pending;
+    uint32_t event_type;
+    char *name;
+} SCLPEvent;
+
+typedef struct SCLPEventClass {
+    DeviceClass parent_class;
+    int (*init)(SCLPEvent *event);
+    int (*exit)(SCLPEvent *event);
+
+    /* get SCLP's send mask */
+    unsigned int (*get_send_mask)(void);
+
+    /* get SCLP's receive mask */
+    unsigned int (*get_receive_mask)(void);
+
+    int (*read_event_data)(SCLPEvent *event, EventBufferHeader *evt_buf_hdr,
+                           int *slen);
+
+    int (*write_event_data)(SCLPEvent *event, EventBufferHeader *evt_buf_hdr);
+
+    /* returns the supported event type */
+    int (*event_type)(void);
+
+} SCLPEventClass;
+
+static inline void lock(SCLPEvent *event)
+{
+    qemu_mutex_lock(&event->lock);
+}
+
+static inline void unlock(SCLPEvent *event)
+{
+    qemu_mutex_unlock(&event->lock);
+}
+
+#endif
diff --git a/hw/s390-sclp.c b/hw/s390-sclp.c
index 74a3e66..4ee04b1 100644
--- a/hw/s390-sclp.c
+++ b/hw/s390-sclp.c
@@ -44,10 +44,7 @@ static int sclp_execute(SCCB *sccb, uint64_t code)
         r = read_SCP_info(sccb);
         break;
     default:
-#ifdef DEBUG_HELPER
-        printf("KVM: invalid sclp call 0x%x / 0x%" PRIx64 "x\n", sccb, code);
-#endif
-        sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
+        r = sclp_bus->event_facility->sclp_command_handler(sccb, code);
         break;
     }
     return r;
@@ -88,10 +85,12 @@ out:
 
 void sclp_service_interrupt(uint32_t sccb)
 {
-    if (!sccb) {
+    int event_pending = sclp_bus->event_facility->event_pending();
+
+    if (!event_pending && !sccb) {
         return;
     }
-    s390_sclp_extint(sccb & ~3);
+    s390_sclp_extint((sccb & ~3) + event_pending);
 }
 
 /* qemu object creation and initialization functions */
@@ -115,6 +114,9 @@ SCLPS390Bus *s390_sclp_bus_init(void)
     bus_state = qbus_create(TYPE_S390_SCLP_BUS, dev, "s390-sclp-bus");
     bus_state->allow_hotplug = 0;
 
+    dev = qdev_create(bus_state, "s390-sclp-event-facility");
+    qdev_init_nofail(dev);
+
     bus = DO_UPCAST(SCLPS390Bus, bus, bus_state);
     return bus;
 }
@@ -140,9 +142,44 @@ static TypeInfo s390_sclp_bridge_info = {
     .class_init    = s390_sclp_bridge_class_init,
 };
 
+static int s390_sclp_busdev_init(DeviceState *dev)
+{
+    int r;
+    S390SCLPDevice *sdev = (S390SCLPDevice *)dev;
+    S390SCLPDeviceClass *sclp = SCLP_S390_DEVICE_GET_CLASS(dev);
+    SCLPS390Bus *bus = DO_UPCAST(SCLPS390Bus, bus, sdev->qdev.parent_bus);
+
+    r = sclp->init(sdev);
+    if (!r) {
+        assert(sdev->event_pending);
+        assert(sdev->sclp_command_handler);
+    }
+    bus->event_facility = sdev;
+
+    return r;
+}
+
+static void s390_sclp_device_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->init = s390_sclp_busdev_init;
+    dc->bus_type = TYPE_S390_SCLP_BUS;
+}
+
+static TypeInfo s390_sclp_device_info = {
+    .name = TYPE_DEVICE_S390_SCLP,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(S390SCLPDevice),
+    .class_init = s390_sclp_device_class_init,
+    .class_size = sizeof(S390SCLPDeviceClass),
+    .abstract = true,
+};
+
 static void s390_sclp_register_types(void)
 {
     type_register_static(&s390_sclp_bridge_info);
     type_register_static(&s390_sclp_bus_info);
+    type_register_static(&s390_sclp_device_info);
 }
 type_init(s390_sclp_register_types)
diff --git a/hw/s390-sclp.h b/hw/s390-sclp.h
index f7bf140..24014eb 100644
--- a/hw/s390-sclp.h
+++ b/hw/s390-sclp.h
@@ -19,15 +19,35 @@
 /* SCLP command codes */
 #define SCLP_CMDW_READ_SCP_INFO                 0x00020001
 #define SCLP_CMDW_READ_SCP_INFO_FORCED          0x00120001
+#define SCLP_CMD_READ_EVENT_DATA                0x00770005
+#define SCLP_CMD_WRITE_EVENT_DATA               0x00760005
+#define SCLP_CMD_READ_EVENT_DATA                0x00770005
+#define SCLP_CMD_WRITE_EVENT_DATA               0x00760005
+#define SCLP_CMD_WRITE_EVENT_MASK               0x00780005
 
 /* SCLP response codes */
 #define SCLP_RC_NORMAL_READ_COMPLETION          0x0010
+#define SCLP_RC_NORMAL_COMPLETION               0x0020
 #define SCLP_RC_INVALID_SCLP_COMMAND            0x01f0
+#define SCLP_RC_CONTAINED_EQUIPMENT_CHECK       0x0340
+#define SCLP_RC_INSUFFICIENT_SCCB_LENGTH        0x0300
+#define SCLP_RC_INVALID_FUNCTION                0x40f0
+#define SCLP_RC_NO_EVENT_BUFFERS_STORED         0x60f0
+#define SCLP_RC_INVALID_SELECTION_MASK          0x70f0
+#define SCLP_RC_INCONSISTENT_LENGTHS            0x72f0
+#define SCLP_RC_EVENT_BUFFER_SYNTAX_ERROR       0x73f0
+#define SCLP_RC_INVALID_MASK_LENGTH             0x74f0
+
 
 /* Service Call Control Block (SCCB) and its elements */
 
 #define SCCB_SIZE 4096
 
+#define SCLP_VARIABLE_LENGTH_RESPONSE           0x80
+#define SCLP_EVENT_BUFFER_ACCEPTED              0x80
+
+#define SCLP_FC_NORMAL_WRITE                    0
+
 /*
  * Normally packed structures are not the right thing to do, since all code
  * must take care of endianess. We cant use ldl_phys and friends for two
@@ -63,14 +83,37 @@ typedef struct SCCB {
 
 #define TYPE_S390_SCLP_BUS "s390-sclp-bus"
 
+#define TYPE_DEVICE_S390_SCLP "s390-sclp-device"
+#define SCLP_S390_DEVIVE(obj) \
+     OBJECT_CHECK(S390SCLPDevice, (obj), TYPE_DEVICE_S390_SCLP)
+#define SCLP_S390_DEVICE_CLASS(klass) \
+     OBJECT_CLASS_CHECK(S390SCLPDeviceClass, (klass), \
+             TYPE_DEVICE_S390_SCLP)
+#define SCLP_S390_DEVICE_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(S390SCLPDeviceClass, (obj), \
+             TYPE_DEVICE_S390_SCLP)
+
+typedef struct SCLPEventFacility SCLPEventFacility;
+
 typedef struct S390SCLPDevice {
     DeviceState qdev;
+    SCLPEventFacility *instance;
+    int (*sclp_command_handler)(SCCB *sccb, uint64_t code);
+    bool (*event_pending)(void);
 } S390SCLPDevice;
 
 typedef struct SCLPS390Bus {
     BusState bus;
+    S390SCLPDevice *event_facility;
 } SCLPS390Bus;
 
+typedef struct S390SCLPDeviceClass {
+    DeviceClass qdev;
+
+    int (*init)(S390SCLPDevice *sdev);
+
+} S390SCLPDeviceClass;
+
 extern SCLPS390Bus *sclp_bus;
 
 SCLPS390Bus *s390_sclp_bus_init(void);
diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
index b2d577b..5ebde3b 100644
--- a/hw/s390x/Makefile.objs
+++ b/hw/s390x/Makefile.objs
@@ -1,4 +1,4 @@
 obj-y = s390-virtio-bus.o s390-virtio.o
-obj-y += s390-sclp.o
+obj-y += s390-sclp.o s390-event-facility.o
 
 obj-y := $(addprefix ../,$(obj-y))
-- 
1.7.10.5