hw/s390x/event-facility.c - third_party/qemu - Git at Google

 /*
  * SCLP
  *    Event Facility
  *       handles SCLP event types
  *          - Signal Quiesce - system power down
  *          - ASCII Console Data - VT220 read and write
  *
  * Copyright IBM, Corp. 2012
  *
  * Authors:
  *  Heinz Graalfs <graalfs@de.ibm.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or (at your
  * option) any later version.  See the COPYING file in the top-level directory.
  *
  */

 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/module.h"

 #include "hw/s390x/sclp.h"
 #include "migration/vmstate.h"
 #include "hw/s390x/event-facility.h"

 typedef struct SCLPEventsBus {
     BusState qbus;
 } SCLPEventsBus;

 /* we need to save 32 bit chunks for compatibility */
 #if HOST_BIG_ENDIAN
 #define RECV_MASK_LOWER 1
 #define RECV_MASK_UPPER 0
 #else /* little endian host */
 #define RECV_MASK_LOWER 0
 #define RECV_MASK_UPPER 1
 #endif

 struct SCLPEventFacility {
     SysBusDevice parent_obj;
     SCLPEventsBus sbus;
     SCLPEvent quiesce, cpu_hotplug;
     /* guest's receive mask */
     union {
         uint32_t receive_mask_pieces[2];
         sccb_mask_t receive_mask;
     };
     /*
      * when false, we keep the same broken, backwards compatible behaviour as
      * before, allowing only masks of size exactly 4; when true, we implement
      * the architecture correctly, allowing all valid mask sizes. Needed for
      * migration toward older versions.
      */
     bool allow_all_mask_sizes;
     /* length of the receive mask */
     uint16_t mask_length;
 };

 /* return true if any child has event pending set */
 static bool event_pending(SCLPEventFacility *ef)
 {
     BusChild *kid;
     SCLPEvent *event;
     SCLPEventClass *event_class;

     QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
         DeviceState *qdev = kid->child;
         event = DO_UPCAST(SCLPEvent, qdev, qdev);
         event_class = SCLP_EVENT_GET_CLASS(event);
         if (event->event_pending &&
             event_class->get_send_mask() & ef->receive_mask) {
             return true;
         }
     }
     return false;
 }

 static sccb_mask_t get_host_send_mask(SCLPEventFacility *ef)
 {
     sccb_mask_t mask;
     BusChild *kid;
     SCLPEventClass *child;

     mask = 0;

     QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
         DeviceState *qdev = kid->child;
         child = SCLP_EVENT_GET_CLASS((SCLPEvent *) qdev);
         mask |= child->get_send_mask();
     }
     return mask;
 }

 static sccb_mask_t get_host_receive_mask(SCLPEventFacility *ef)
 {
     sccb_mask_t mask;
     BusChild *kid;
     SCLPEventClass *child;

     mask = 0;

     QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
         DeviceState *qdev = kid->child;
         child = SCLP_EVENT_GET_CLASS((SCLPEvent *) qdev);
         mask |= child->get_receive_mask();
     }
     return mask;
 }

 static uint16_t write_event_length_check(SCCB *sccb)
 {
     int slen;
     unsigned elen = 0;
     EventBufferHeader *event;
     WriteEventData *wed = (WriteEventData *) sccb;

     event = (EventBufferHeader *) &wed->ebh;
     for (slen = sccb_data_len(sccb); slen > 0; slen -= elen) {
         elen = be16_to_cpu(event->length);
         if (elen < sizeof(*event) || elen > slen) {
             return SCLP_RC_EVENT_BUFFER_SYNTAX_ERROR;
         }
         event = (void *) event + elen;
     }
     if (slen) {
         return SCLP_RC_INCONSISTENT_LENGTHS;
     }
     return SCLP_RC_NORMAL_COMPLETION;
 }

 static uint16_t handle_write_event_buf(SCLPEventFacility *ef,
                                        EventBufferHeader *event_buf, SCCB *sccb)
 {
     uint16_t rc;
     BusChild *kid;
     SCLPEvent *event;
     SCLPEventClass *ec;

     rc = SCLP_RC_INVALID_FUNCTION;

     QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
         DeviceState *qdev = kid->child;
         event = (SCLPEvent *) qdev;
         ec = SCLP_EVENT_GET_CLASS(event);

         if (ec->write_event_data &&
             ec->can_handle_event(event_buf->type)) {
             rc = ec->write_event_data(event, event_buf);
             break;
         }
     }
     return rc;
 }

 static uint16_t handle_sccb_write_events(SCLPEventFacility *ef, SCCB *sccb)
 {
     uint16_t rc;
     int slen;
     unsigned elen = 0;
     EventBufferHeader *event_buf;
     WriteEventData *wed = (WriteEventData *) sccb;

     event_buf = &wed->ebh;
     rc = SCLP_RC_NORMAL_COMPLETION;

     /* loop over all contained event buffers */
     for (slen = sccb_data_len(sccb); 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 (rc != SCLP_RC_NORMAL_COMPLETION) {
             event_buf->flags &= ~(SCLP_EVENT_BUFFER_ACCEPTED);
         } else {
             rc = handle_write_event_buf(ef, event_buf, sccb);
         }
         event_buf = (void *) event_buf + elen;
     }
     return rc;
 }

 static void write_event_data(SCLPEventFacility *ef, SCCB *sccb)
 {
     if (sccb->h.function_code != SCLP_FC_NORMAL_WRITE) {
         sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
         return;
     }
     if (be16_to_cpu(sccb->h.length) < 8) {
         sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
         return;
     }
     /* first do a sanity check of the write events */
     sccb->h.response_code = cpu_to_be16(write_event_length_check(sccb));

     /* if no early error, then execute */
     if (sccb->h.response_code == be16_to_cpu(SCLP_RC_NORMAL_COMPLETION)) {
         sccb->h.response_code =
                 cpu_to_be16(handle_sccb_write_events(ef, sccb));
     }
 }

 static uint16_t handle_sccb_read_events(SCLPEventFacility *ef, SCCB *sccb,
                                         sccb_mask_t mask)
 {
     uint16_t rc;
     int slen;
     unsigned elen;
     BusChild *kid;
     SCLPEvent *event;
     SCLPEventClass *ec;
     EventBufferHeader *event_buf;
     ReadEventData *red = (ReadEventData *) sccb;

     event_buf = &red->ebh;
     event_buf->length = 0;
     slen = sccb_data_len(sccb);

     rc = SCLP_RC_NO_EVENT_BUFFERS_STORED;

     QTAILQ_FOREACH(kid, &ef->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)) {
                 elen = be16_to_cpu(event_buf->length);
                 event_buf = (EventBufferHeader *) ((char *)event_buf + elen);
                 rc = SCLP_RC_NORMAL_COMPLETION;
             }
         }
     }

     if (sccb->h.control_mask[2] & SCLP_VARIABLE_LENGTH_RESPONSE) {
         /* architecture suggests to reset variable-length-response bit */
         sccb->h.control_mask[2] &= ~SCLP_VARIABLE_LENGTH_RESPONSE;
         /* with a new length value */
         sccb->h.length = cpu_to_be16(SCCB_SIZE - slen);
     }
     return rc;
 }

 /* copy up to src_len bytes and fill the rest of dst with zeroes */
 static void copy_mask(uint8_t *dst, uint8_t *src, uint16_t dst_len,
                       uint16_t src_len)
 {
     int i;

     for (i = 0; i < dst_len; i++) {
         dst[i] = i < src_len ? src[i] : 0;
     }
 }

 static void read_event_data(SCLPEventFacility *ef, SCCB *sccb)
 {
     sccb_mask_t sclp_active_selection_mask;
     sccb_mask_t 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);
         return;
     }

     switch (sccb->h.function_code) {
     case SCLP_UNCONDITIONAL_READ:
         sccb->h.response_code = cpu_to_be16(
             handle_sccb_read_events(ef, sccb, ef->receive_mask));
         break;
     case SCLP_SELECTIVE_READ:
         /* get active selection mask */
         sclp_cp_receive_mask = ef->receive_mask;

         copy_mask((uint8_t *)&sclp_active_selection_mask, (uint8_t *)&red->mask,
                   sizeof(sclp_active_selection_mask), ef->mask_length);
         sclp_active_selection_mask = be64_to_cpu(sclp_active_selection_mask);
         if (!sclp_cp_receive_mask ||
             (sclp_active_selection_mask & ~sclp_cp_receive_mask)) {
             sccb->h.response_code =
                     cpu_to_be16(SCLP_RC_INVALID_SELECTION_MASK);
         } else {
             sccb->h.response_code = cpu_to_be16(
                 handle_sccb_read_events(ef, sccb, sclp_active_selection_mask));
         }
         break;
     default:
         sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
     }
 }

 static void write_event_mask(SCLPEventFacility *ef, SCCB *sccb)
 {
     WriteEventMask *we_mask = (WriteEventMask *) sccb;
     uint16_t mask_length = be16_to_cpu(we_mask->mask_length);
     sccb_mask_t tmp_mask;

     if (!mask_length || (mask_length > SCLP_EVENT_MASK_LEN_MAX) ||
         ((mask_length != 4) && !ef->allow_all_mask_sizes)) {
         sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_MASK_LENGTH);
         return;
     }

     /*
      * Note: We currently only support masks up to 8 byte length;
      *       the remainder is filled up with zeroes. Older Linux
      *       kernels use a 4 byte mask length, newer ones can use both
      *       8 or 4 depending on what is available on the host.
      */

     /* keep track of the guest's capability masks */
     copy_mask((uint8_t *)&tmp_mask, WEM_CP_RECEIVE_MASK(we_mask, mask_length),
               sizeof(tmp_mask), mask_length);
     ef->receive_mask = be64_to_cpu(tmp_mask);

     /* return the SCLP's capability masks to the guest */
     tmp_mask = cpu_to_be64(get_host_receive_mask(ef));
     copy_mask(WEM_RECEIVE_MASK(we_mask, mask_length), (uint8_t *)&tmp_mask,
               mask_length, sizeof(tmp_mask));
     tmp_mask = cpu_to_be64(get_host_send_mask(ef));
     copy_mask(WEM_SEND_MASK(we_mask, mask_length), (uint8_t *)&tmp_mask,
               mask_length, sizeof(tmp_mask));

     sccb->h.response_code = cpu_to_be16(SCLP_RC_NORMAL_COMPLETION);
     ef->mask_length = mask_length;
 }

 /* qemu object creation and initialization functions */

 #define TYPE_SCLP_EVENTS_BUS "s390-sclp-events-bus"

 static const TypeInfo sclp_events_bus_info = {
     .name = TYPE_SCLP_EVENTS_BUS,
     .parent = TYPE_BUS,
 };

 static void command_handler(SCLPEventFacility *ef, SCCB *sccb, uint64_t code)
 {
     switch (code & SCLP_CMD_CODE_MASK) {
     case SCLP_CMD_READ_EVENT_DATA:
         read_event_data(ef, sccb);
         break;
     case SCLP_CMD_WRITE_EVENT_DATA:
         write_event_data(ef, sccb);
         break;
     case SCLP_CMD_WRITE_EVENT_MASK:
         write_event_mask(ef, sccb);
         break;
     }
 }

 static bool vmstate_event_facility_mask64_needed(void *opaque)
 {
     SCLPEventFacility *ef = opaque;

     return (ef->receive_mask & 0xFFFFFFFF) != 0;
 }

 static bool vmstate_event_facility_mask_length_needed(void *opaque)
 {
     SCLPEventFacility *ef = opaque;

     return ef->allow_all_mask_sizes;
 }

 static const VMStateDescription vmstate_event_facility_mask64 = {
     .name = "vmstate-event-facility/mask64",
     .version_id = 0,
     .minimum_version_id = 0,
     .needed = vmstate_event_facility_mask64_needed,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(receive_mask_pieces[RECV_MASK_LOWER], SCLPEventFacility),
         VMSTATE_END_OF_LIST()
      }
 };

 static const VMStateDescription vmstate_event_facility_mask_length = {
     .name = "vmstate-event-facility/mask_length",
     .version_id = 0,
     .minimum_version_id = 0,
     .needed = vmstate_event_facility_mask_length_needed,
     .fields = (VMStateField[]) {
         VMSTATE_UINT16(mask_length, SCLPEventFacility),
         VMSTATE_END_OF_LIST()
      }
 };

 static const VMStateDescription vmstate_event_facility = {
     .name = "vmstate-event-facility",
     .version_id = 0,
     .minimum_version_id = 0,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32(receive_mask_pieces[RECV_MASK_UPPER], SCLPEventFacility),
         VMSTATE_END_OF_LIST()
      },
     .subsections = (const VMStateDescription * []) {
         &vmstate_event_facility_mask64,
         &vmstate_event_facility_mask_length,
         NULL
      }
 };

 static void sclp_event_set_allow_all_mask_sizes(Object *obj, bool value,
                                                        Error **errp)
 {
     SCLPEventFacility *ef = (SCLPEventFacility *)obj;

     ef->allow_all_mask_sizes = value;
 }

 static bool sclp_event_get_allow_all_mask_sizes(Object *obj, Error **errp)
 {
     SCLPEventFacility *ef = (SCLPEventFacility *)obj;

     return ef->allow_all_mask_sizes;
 }

 static void init_event_facility(Object *obj)
 {
     SCLPEventFacility *event_facility = EVENT_FACILITY(obj);
     DeviceState *sdev = DEVICE(obj);

     event_facility->mask_length = 4;
     event_facility->allow_all_mask_sizes = true;
     object_property_add_bool(obj, "allow_all_mask_sizes",
                              sclp_event_get_allow_all_mask_sizes,
                              sclp_event_set_allow_all_mask_sizes);

     /* Spawn a new bus for SCLP events */
     qbus_init(&event_facility->sbus, sizeof(event_facility->sbus),
               TYPE_SCLP_EVENTS_BUS, sdev, NULL);

     object_initialize_child(obj, TYPE_SCLP_QUIESCE,
                             &event_facility->quiesce,
                             TYPE_SCLP_QUIESCE);

     object_initialize_child(obj, TYPE_SCLP_CPU_HOTPLUG,
                             &event_facility->cpu_hotplug,
                             TYPE_SCLP_CPU_HOTPLUG);
 }

 static void realize_event_facility(DeviceState *dev, Error **errp)
 {
     SCLPEventFacility *event_facility = EVENT_FACILITY(dev);

     if (!qdev_realize(DEVICE(&event_facility->quiesce),
                       BUS(&event_facility->sbus), errp)) {
         return;
     }
     if (!qdev_realize(DEVICE(&event_facility->cpu_hotplug),
                       BUS(&event_facility->sbus), errp)) {
         qdev_unrealize(DEVICE(&event_facility->quiesce));
         return;
     }
 }

 static void reset_event_facility(DeviceState *dev)
 {
     SCLPEventFacility *sdev = EVENT_FACILITY(dev);

     sdev->receive_mask = 0;
 }

 static void init_event_facility_class(ObjectClass *klass, void *data)
 {
     SysBusDeviceClass *sbdc = SYS_BUS_DEVICE_CLASS(klass);
     DeviceClass *dc = DEVICE_CLASS(sbdc);
     SCLPEventFacilityClass *k = EVENT_FACILITY_CLASS(dc);

     dc->realize = realize_event_facility;
     dc->reset = reset_event_facility;
     dc->vmsd = &vmstate_event_facility;
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
     k->command_handler = command_handler;
     k->event_pending = event_pending;
 }

 static const TypeInfo sclp_event_facility_info = {
     .name          = TYPE_SCLP_EVENT_FACILITY,
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_init = init_event_facility,
     .instance_size = sizeof(SCLPEventFacility),
     .class_init    = init_event_facility_class,
     .class_size    = sizeof(SCLPEventFacilityClass),
 };

 static void event_realize(DeviceState *qdev, Error **errp)
 {
     SCLPEvent *event = SCLP_EVENT(qdev);
     SCLPEventClass *child = SCLP_EVENT_GET_CLASS(event);

     if (child->init) {
         int rc = child->init(event);
         if (rc < 0) {
             error_setg(errp, "SCLP event initialization failed.");
             return;
         }
     }
 }

 static void event_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);

     dc->bus_type = TYPE_SCLP_EVENTS_BUS;
     dc->realize = event_realize;
 }

 static const TypeInfo 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(&sclp_events_bus_info);
     type_register_static(&sclp_event_facility_info);
     type_register_static(&sclp_event_type_info);
 }

 type_init(register_types)

 BusState *sclp_get_event_facility_bus(void)
 {
     Object *busobj;
     SCLPEventsBus *sbus;

     busobj = object_resolve_path_type("", TYPE_SCLP_EVENTS_BUS, NULL);
     sbus = OBJECT_CHECK(SCLPEventsBus, busobj, TYPE_SCLP_EVENTS_BUS);
     if (!sbus) {
         return NULL;
     }

     return &sbus->qbus;
 }
	/*
	* SCLP
	* Event Facility
	* handles SCLP event types
	* - Signal Quiesce - system power down
	* - ASCII Console Data - VT220 read and write
	*
	* Copyright IBM, Corp. 2012
	*
	* Authors:
	* Heinz Graalfs <graalfs@de.ibm.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2 or (at your
	* option) any later version. See the COPYING file in the top-level directory.
	*
	*/

	#include "qemu/osdep.h"
	#include "qapi/error.h"
	#include "qemu/module.h"

	#include "hw/s390x/sclp.h"
	#include "migration/vmstate.h"
	#include "hw/s390x/event-facility.h"

	typedef struct SCLPEventsBus {
	BusState qbus;
	} SCLPEventsBus;

	/* we need to save 32 bit chunks for compatibility */
	#if HOST_BIG_ENDIAN
	#define RECV_MASK_LOWER 1
	#define RECV_MASK_UPPER 0
	#else /* little endian host */
	#define RECV_MASK_LOWER 0
	#define RECV_MASK_UPPER 1
	#endif

	struct SCLPEventFacility {
	SysBusDevice parent_obj;
	SCLPEventsBus sbus;
	SCLPEvent quiesce, cpu_hotplug;
	/* guest's receive mask */
	union {
	uint32_t receive_mask_pieces[2];
	sccb_mask_t receive_mask;
	};
	/*
	* when false, we keep the same broken, backwards compatible behaviour as
	* before, allowing only masks of size exactly 4; when true, we implement
	* the architecture correctly, allowing all valid mask sizes. Needed for
	* migration toward older versions.
	*/
	bool allow_all_mask_sizes;
	/* length of the receive mask */
	uint16_t mask_length;
	};

	/* return true if any child has event pending set */
	static bool event_pending(SCLPEventFacility *ef)
	{
	BusChild *kid;
	SCLPEvent *event;
	SCLPEventClass *event_class;

	QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
	DeviceState *qdev = kid->child;
	event = DO_UPCAST(SCLPEvent, qdev, qdev);
	event_class = SCLP_EVENT_GET_CLASS(event);
	if (event->event_pending &&
	event_class->get_send_mask() & ef->receive_mask) {
	return true;
	}
	}
	return false;
	}

	static sccb_mask_t get_host_send_mask(SCLPEventFacility *ef)
	{
	sccb_mask_t mask;
	BusChild *kid;
	SCLPEventClass *child;

	mask = 0;

	QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
	DeviceState *qdev = kid->child;
	child = SCLP_EVENT_GET_CLASS((SCLPEvent *) qdev);
	mask \|= child->get_send_mask();
	}
	return mask;
	}

	static sccb_mask_t get_host_receive_mask(SCLPEventFacility *ef)
	{
	sccb_mask_t mask;
	BusChild *kid;
	SCLPEventClass *child;

	mask = 0;

	QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
	DeviceState *qdev = kid->child;
	child = SCLP_EVENT_GET_CLASS((SCLPEvent *) qdev);
	mask \|= child->get_receive_mask();
	}
	return mask;
	}

	static uint16_t write_event_length_check(SCCB *sccb)
	{
	int slen;
	unsigned elen = 0;
	EventBufferHeader *event;
	WriteEventData wed = (WriteEventData ) sccb;

	event = (EventBufferHeader *) &wed->ebh;
	for (slen = sccb_data_len(sccb); slen > 0; slen -= elen) {
	elen = be16_to_cpu(event->length);
	if (elen < sizeof(*event) \|\| elen > slen) {
	return SCLP_RC_EVENT_BUFFER_SYNTAX_ERROR;
	}
	event = (void *) event + elen;
	}
	if (slen) {
	return SCLP_RC_INCONSISTENT_LENGTHS;
	}
	return SCLP_RC_NORMAL_COMPLETION;
	}

	static uint16_t handle_write_event_buf(SCLPEventFacility *ef,
	EventBufferHeader event_buf, SCCB sccb)
	{
	uint16_t rc;
	BusChild *kid;
	SCLPEvent *event;
	SCLPEventClass *ec;

	rc = SCLP_RC_INVALID_FUNCTION;

	QTAILQ_FOREACH(kid, &ef->sbus.qbus.children, sibling) {
	DeviceState *qdev = kid->child;
	event = (SCLPEvent *) qdev;
	ec = SCLP_EVENT_GET_CLASS(event);

	if (ec->write_event_data &&
	ec->can_handle_event(event_buf->type)) {
	rc = ec->write_event_data(event, event_buf);
	break;
	}
	}
	return rc;
	}

	static uint16_t handle_sccb_write_events(SCLPEventFacility ef, SCCB sccb)
	{
	uint16_t rc;
	int slen;
	unsigned elen = 0;
	EventBufferHeader *event_buf;
	WriteEventData wed = (WriteEventData ) sccb;

	event_buf = &wed->ebh;
	rc = SCLP_RC_NORMAL_COMPLETION;

	/* loop over all contained event buffers */
	for (slen = sccb_data_len(sccb); 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 (rc != SCLP_RC_NORMAL_COMPLETION) {
	event_buf->flags &= ~(SCLP_EVENT_BUFFER_ACCEPTED);
	} else {
	rc = handle_write_event_buf(ef, event_buf, sccb);
	}
	event_buf = (void *) event_buf + elen;
	}
	return rc;
	}

	static void write_event_data(SCLPEventFacility ef, SCCB sccb)
	{
	if (sccb->h.function_code != SCLP_FC_NORMAL_WRITE) {
	sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
	return;
	}
	if (be16_to_cpu(sccb->h.length) < 8) {
	sccb->h.response_code = cpu_to_be16(SCLP_RC_INSUFFICIENT_SCCB_LENGTH);
	return;
	}
	/* first do a sanity check of the write events */
	sccb->h.response_code = cpu_to_be16(write_event_length_check(sccb));

	/* if no early error, then execute */
	if (sccb->h.response_code == be16_to_cpu(SCLP_RC_NORMAL_COMPLETION)) {
	sccb->h.response_code =
	cpu_to_be16(handle_sccb_write_events(ef, sccb));
	}
	}

	static uint16_t handle_sccb_read_events(SCLPEventFacility ef, SCCB sccb,
	sccb_mask_t mask)
	{
	uint16_t rc;
	int slen;
	unsigned elen;
	BusChild *kid;
	SCLPEvent *event;
	SCLPEventClass *ec;
	EventBufferHeader *event_buf;
	ReadEventData red = (ReadEventData ) sccb;

	event_buf = &red->ebh;
	event_buf->length = 0;
	slen = sccb_data_len(sccb);

	rc = SCLP_RC_NO_EVENT_BUFFERS_STORED;

	QTAILQ_FOREACH(kid, &ef->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)) {
	elen = be16_to_cpu(event_buf->length);
	event_buf = (EventBufferHeader ) ((char )event_buf + elen);
	rc = SCLP_RC_NORMAL_COMPLETION;
	}
	}
	}

	if (sccb->h.control_mask[2] & SCLP_VARIABLE_LENGTH_RESPONSE) {
	/* architecture suggests to reset variable-length-response bit */
	sccb->h.control_mask[2] &= ~SCLP_VARIABLE_LENGTH_RESPONSE;
	/* with a new length value */
	sccb->h.length = cpu_to_be16(SCCB_SIZE - slen);
	}
	return rc;
	}

	/* copy up to src_len bytes and fill the rest of dst with zeroes */
	static void copy_mask(uint8_t dst, uint8_t src, uint16_t dst_len,
	uint16_t src_len)
	{
	int i;

	for (i = 0; i < dst_len; i++) {
	dst[i] = i < src_len ? src[i] : 0;
	}
	}

	static void read_event_data(SCLPEventFacility ef, SCCB sccb)
	{
	sccb_mask_t sclp_active_selection_mask;
	sccb_mask_t 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);
	return;
	}

	switch (sccb->h.function_code) {
	case SCLP_UNCONDITIONAL_READ:
	sccb->h.response_code = cpu_to_be16(
	handle_sccb_read_events(ef, sccb, ef->receive_mask));
	break;
	case SCLP_SELECTIVE_READ:
	/* get active selection mask */
	sclp_cp_receive_mask = ef->receive_mask;

	copy_mask((uint8_t )&sclp_active_selection_mask, (uint8_t )&red->mask,
	sizeof(sclp_active_selection_mask), ef->mask_length);
	sclp_active_selection_mask = be64_to_cpu(sclp_active_selection_mask);
	if (!sclp_cp_receive_mask \|\|
	(sclp_active_selection_mask & ~sclp_cp_receive_mask)) {
	sccb->h.response_code =
	cpu_to_be16(SCLP_RC_INVALID_SELECTION_MASK);
	} else {
	sccb->h.response_code = cpu_to_be16(
	handle_sccb_read_events(ef, sccb, sclp_active_selection_mask));
	}
	break;
	default:
	sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_FUNCTION);
	}
	}

	static void write_event_mask(SCLPEventFacility ef, SCCB sccb)
	{
	WriteEventMask we_mask = (WriteEventMask ) sccb;
	uint16_t mask_length = be16_to_cpu(we_mask->mask_length);
	sccb_mask_t tmp_mask;

	if (!mask_length \|\| (mask_length > SCLP_EVENT_MASK_LEN_MAX) \|\|
	((mask_length != 4) && !ef->allow_all_mask_sizes)) {
	sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_MASK_LENGTH);
	return;
	}

	/*
	* Note: We currently only support masks up to 8 byte length;
	* the remainder is filled up with zeroes. Older Linux
	* kernels use a 4 byte mask length, newer ones can use both
	* 8 or 4 depending on what is available on the host.
	*/

	/* keep track of the guest's capability masks */
	copy_mask((uint8_t *)&tmp_mask, WEM_CP_RECEIVE_MASK(we_mask, mask_length),
	sizeof(tmp_mask), mask_length);
	ef->receive_mask = be64_to_cpu(tmp_mask);

	/* return the SCLP's capability masks to the guest */
	tmp_mask = cpu_to_be64(get_host_receive_mask(ef));
	copy_mask(WEM_RECEIVE_MASK(we_mask, mask_length), (uint8_t *)&tmp_mask,
	mask_length, sizeof(tmp_mask));
	tmp_mask = cpu_to_be64(get_host_send_mask(ef));
	copy_mask(WEM_SEND_MASK(we_mask, mask_length), (uint8_t *)&tmp_mask,
	mask_length, sizeof(tmp_mask));

	sccb->h.response_code = cpu_to_be16(SCLP_RC_NORMAL_COMPLETION);
	ef->mask_length = mask_length;
	}

	/* qemu object creation and initialization functions */

	#define TYPE_SCLP_EVENTS_BUS "s390-sclp-events-bus"

	static const TypeInfo sclp_events_bus_info = {
	.name = TYPE_SCLP_EVENTS_BUS,
	.parent = TYPE_BUS,
	};

	static void command_handler(SCLPEventFacility ef, SCCB sccb, uint64_t code)
	{
	switch (code & SCLP_CMD_CODE_MASK) {
	case SCLP_CMD_READ_EVENT_DATA:
	read_event_data(ef, sccb);
	break;
	case SCLP_CMD_WRITE_EVENT_DATA:
	write_event_data(ef, sccb);
	break;
	case SCLP_CMD_WRITE_EVENT_MASK:
	write_event_mask(ef, sccb);
	break;
	}
	}

	static bool vmstate_event_facility_mask64_needed(void *opaque)
	{
	SCLPEventFacility *ef = opaque;

	return (ef->receive_mask & 0xFFFFFFFF) != 0;
	}

	static bool vmstate_event_facility_mask_length_needed(void *opaque)
	{
	SCLPEventFacility *ef = opaque;

	return ef->allow_all_mask_sizes;
	}

	static const VMStateDescription vmstate_event_facility_mask64 = {
	.name = "vmstate-event-facility/mask64",
	.version_id = 0,
	.minimum_version_id = 0,
	.needed = vmstate_event_facility_mask64_needed,
	.fields = (VMStateField[]) {
	VMSTATE_UINT32(receive_mask_pieces[RECV_MASK_LOWER], SCLPEventFacility),
	VMSTATE_END_OF_LIST()
	}
	};

	static const VMStateDescription vmstate_event_facility_mask_length = {
	.name = "vmstate-event-facility/mask_length",
	.version_id = 0,
	.minimum_version_id = 0,
	.needed = vmstate_event_facility_mask_length_needed,
	.fields = (VMStateField[]) {
	VMSTATE_UINT16(mask_length, SCLPEventFacility),
	VMSTATE_END_OF_LIST()
	}
	};

	static const VMStateDescription vmstate_event_facility = {
	.name = "vmstate-event-facility",
	.version_id = 0,
	.minimum_version_id = 0,
	.fields = (VMStateField[]) {
	VMSTATE_UINT32(receive_mask_pieces[RECV_MASK_UPPER], SCLPEventFacility),
	VMSTATE_END_OF_LIST()
	},
	.subsections = (const VMStateDescription * []) {
	&vmstate_event_facility_mask64,
	&vmstate_event_facility_mask_length,
	NULL
	}
	};

	static void sclp_event_set_allow_all_mask_sizes(Object *obj, bool value,
	Error **errp)
	{
	SCLPEventFacility ef = (SCLPEventFacility )obj;

	ef->allow_all_mask_sizes = value;
	}

	static bool sclp_event_get_allow_all_mask_sizes(Object obj, Error *errp)
	{
	SCLPEventFacility ef = (SCLPEventFacility )obj;

	return ef->allow_all_mask_sizes;
	}

	static void init_event_facility(Object *obj)
	{
	SCLPEventFacility *event_facility = EVENT_FACILITY(obj);
	DeviceState *sdev = DEVICE(obj);

	event_facility->mask_length = 4;
	event_facility->allow_all_mask_sizes = true;
	object_property_add_bool(obj, "allow_all_mask_sizes",
	sclp_event_get_allow_all_mask_sizes,
	sclp_event_set_allow_all_mask_sizes);

	/* Spawn a new bus for SCLP events */
	qbus_init(&event_facility->sbus, sizeof(event_facility->sbus),
	TYPE_SCLP_EVENTS_BUS, sdev, NULL);

	object_initialize_child(obj, TYPE_SCLP_QUIESCE,
	&event_facility->quiesce,
	TYPE_SCLP_QUIESCE);

	object_initialize_child(obj, TYPE_SCLP_CPU_HOTPLUG,
	&event_facility->cpu_hotplug,
	TYPE_SCLP_CPU_HOTPLUG);
	}

	static void realize_event_facility(DeviceState dev, Error *errp)
	{
	SCLPEventFacility *event_facility = EVENT_FACILITY(dev);

	if (!qdev_realize(DEVICE(&event_facility->quiesce),
	BUS(&event_facility->sbus), errp)) {
	return;
	}
	if (!qdev_realize(DEVICE(&event_facility->cpu_hotplug),
	BUS(&event_facility->sbus), errp)) {
	qdev_unrealize(DEVICE(&event_facility->quiesce));
	return;
	}
	}

	static void reset_event_facility(DeviceState *dev)
	{
	SCLPEventFacility *sdev = EVENT_FACILITY(dev);

	sdev->receive_mask = 0;
	}

	static void init_event_facility_class(ObjectClass klass, void data)
	{
	SysBusDeviceClass *sbdc = SYS_BUS_DEVICE_CLASS(klass);
	DeviceClass *dc = DEVICE_CLASS(sbdc);
	SCLPEventFacilityClass *k = EVENT_FACILITY_CLASS(dc);

	dc->realize = realize_event_facility;
	dc->reset = reset_event_facility;
	dc->vmsd = &vmstate_event_facility;
	set_bit(DEVICE_CATEGORY_MISC, dc->categories);
	k->command_handler = command_handler;
	k->event_pending = event_pending;
	}

	static const TypeInfo sclp_event_facility_info = {
	.name = TYPE_SCLP_EVENT_FACILITY,
	.parent = TYPE_SYS_BUS_DEVICE,
	.instance_init = init_event_facility,
	.instance_size = sizeof(SCLPEventFacility),
	.class_init = init_event_facility_class,
	.class_size = sizeof(SCLPEventFacilityClass),
	};

	static void event_realize(DeviceState qdev, Error *errp)
	{
	SCLPEvent *event = SCLP_EVENT(qdev);
	SCLPEventClass *child = SCLP_EVENT_GET_CLASS(event);

	if (child->init) {
	int rc = child->init(event);
	if (rc < 0) {
	error_setg(errp, "SCLP event initialization failed.");
	return;
	}
	}
	}

	static void event_class_init(ObjectClass klass, void data)
	{
	DeviceClass *dc = DEVICE_CLASS(klass);

	dc->bus_type = TYPE_SCLP_EVENTS_BUS;
	dc->realize = event_realize;
	}

	static const TypeInfo 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(&sclp_events_bus_info);
	type_register_static(&sclp_event_facility_info);
	type_register_static(&sclp_event_type_info);
	}

	type_init(register_types)

	BusState *sclp_get_event_facility_bus(void)
	{
	Object *busobj;
	SCLPEventsBus *sbus;

	busobj = object_resolve_path_type("", TYPE_SCLP_EVENTS_BUS, NULL);
	sbus = OBJECT_CHECK(SCLPEventsBus, busobj, TYPE_SCLP_EVENTS_BUS);
	if (!sbus) {
	return NULL;
	}

	return &sbus->qbus;
	}