qemu-e2k/hw/ppc/spapr_events.c

/*
 * QEMU PowerPC pSeries Logical Partition (aka sPAPR) hardware System Emulator
 *
 * RTAS events handling
 *
 * Copyright (c) 2012 David Gibson, IBM Corporation.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */
#include "cpu.h"
#include "sysemu/sysemu.h"
#include "sysemu/char.h"
#include "hw/qdev.h"
#include "sysemu/device_tree.h"

#include "hw/ppc/spapr.h"
#include "hw/ppc/spapr_vio.h"
#include "hw/pci/pci.h"
#include "hw/pci-host/spapr.h"
#include "hw/ppc/spapr_drc.h"

#include <libfdt.h>

struct rtas_error_log {
    uint32_t summary;
#define RTAS_LOG_VERSION_MASK                   0xff000000
#define   RTAS_LOG_VERSION_6                    0x06000000
#define RTAS_LOG_SEVERITY_MASK                  0x00e00000
#define   RTAS_LOG_SEVERITY_ALREADY_REPORTED    0x00c00000
#define   RTAS_LOG_SEVERITY_FATAL               0x00a00000
#define   RTAS_LOG_SEVERITY_ERROR               0x00800000
#define   RTAS_LOG_SEVERITY_ERROR_SYNC          0x00600000
#define   RTAS_LOG_SEVERITY_WARNING             0x00400000
#define   RTAS_LOG_SEVERITY_EVENT               0x00200000
#define   RTAS_LOG_SEVERITY_NO_ERROR            0x00000000
#define RTAS_LOG_DISPOSITION_MASK               0x00180000
#define   RTAS_LOG_DISPOSITION_FULLY_RECOVERED  0x00000000
#define   RTAS_LOG_DISPOSITION_LIMITED_RECOVERY 0x00080000
#define   RTAS_LOG_DISPOSITION_NOT_RECOVERED    0x00100000
#define RTAS_LOG_OPTIONAL_PART_PRESENT          0x00040000
#define RTAS_LOG_INITIATOR_MASK                 0x0000f000
#define   RTAS_LOG_INITIATOR_UNKNOWN            0x00000000
#define   RTAS_LOG_INITIATOR_CPU                0x00001000
#define   RTAS_LOG_INITIATOR_PCI                0x00002000
#define   RTAS_LOG_INITIATOR_MEMORY             0x00004000
#define   RTAS_LOG_INITIATOR_HOTPLUG            0x00006000
#define RTAS_LOG_TARGET_MASK                    0x00000f00
#define   RTAS_LOG_TARGET_UNKNOWN               0x00000000
#define   RTAS_LOG_TARGET_CPU                   0x00000100
#define   RTAS_LOG_TARGET_PCI                   0x00000200
#define   RTAS_LOG_TARGET_MEMORY                0x00000400
#define   RTAS_LOG_TARGET_HOTPLUG               0x00000600
#define RTAS_LOG_TYPE_MASK                      0x000000ff
#define   RTAS_LOG_TYPE_OTHER                   0x00000000
#define   RTAS_LOG_TYPE_RETRY                   0x00000001
#define   RTAS_LOG_TYPE_TCE_ERR                 0x00000002
#define   RTAS_LOG_TYPE_INTERN_DEV_FAIL         0x00000003
#define   RTAS_LOG_TYPE_TIMEOUT                 0x00000004
#define   RTAS_LOG_TYPE_DATA_PARITY             0x00000005
#define   RTAS_LOG_TYPE_ADDR_PARITY             0x00000006
#define   RTAS_LOG_TYPE_CACHE_PARITY            0x00000007
#define   RTAS_LOG_TYPE_ADDR_INVALID            0x00000008
#define   RTAS_LOG_TYPE_ECC_UNCORR              0x00000009
#define   RTAS_LOG_TYPE_ECC_CORR                0x0000000a
#define   RTAS_LOG_TYPE_EPOW                    0x00000040
#define   RTAS_LOG_TYPE_HOTPLUG                 0x000000e5
    uint32_t extended_length;
} QEMU_PACKED;

struct rtas_event_log_v6 {
    uint8_t b0;
#define RTAS_LOG_V6_B0_VALID                          0x80
#define RTAS_LOG_V6_B0_UNRECOVERABLE_ERROR            0x40
#define RTAS_LOG_V6_B0_RECOVERABLE_ERROR              0x20
#define RTAS_LOG_V6_B0_DEGRADED_OPERATION             0x10
#define RTAS_LOG_V6_B0_PREDICTIVE_ERROR               0x08
#define RTAS_LOG_V6_B0_NEW_LOG                        0x04
#define RTAS_LOG_V6_B0_BIGENDIAN                      0x02
    uint8_t _resv1;
    uint8_t b2;
#define RTAS_LOG_V6_B2_POWERPC_FORMAT                 0x80
#define RTAS_LOG_V6_B2_LOG_FORMAT_MASK                0x0f
#define   RTAS_LOG_V6_B2_LOG_FORMAT_PLATFORM_EVENT    0x0e
    uint8_t _resv2[9];
    uint32_t company;
#define RTAS_LOG_V6_COMPANY_IBM                 0x49424d00 /* IBM<null> */
} QEMU_PACKED;

struct rtas_event_log_v6_section_header {
    uint16_t section_id;
    uint16_t section_length;
    uint8_t section_version;
    uint8_t section_subtype;
    uint16_t creator_component_id;
} QEMU_PACKED;

struct rtas_event_log_v6_maina {
#define RTAS_LOG_V6_SECTION_ID_MAINA                0x5048 /* PH */
    struct rtas_event_log_v6_section_header hdr;
    uint32_t creation_date; /* BCD: YYYYMMDD */
    uint32_t creation_time; /* BCD: HHMMSS00 */
    uint8_t _platform1[8];
    char creator_id;
    uint8_t _resv1[2];
    uint8_t section_count;
    uint8_t _resv2[4];
    uint8_t _platform2[8];
    uint32_t plid;
    uint8_t _platform3[4];
} QEMU_PACKED;

struct rtas_event_log_v6_mainb {
#define RTAS_LOG_V6_SECTION_ID_MAINB                0x5548 /* UH */
    struct rtas_event_log_v6_section_header hdr;
    uint8_t subsystem_id;
    uint8_t _platform1;
    uint8_t event_severity;
    uint8_t event_subtype;
    uint8_t _platform2[4];
    uint8_t _resv1[2];
    uint16_t action_flags;
    uint8_t _resv2[4];
} QEMU_PACKED;

struct rtas_event_log_v6_epow {
#define RTAS_LOG_V6_SECTION_ID_EPOW                 0x4550 /* EP */
    struct rtas_event_log_v6_section_header hdr;
    uint8_t sensor_value;
#define RTAS_LOG_V6_EPOW_ACTION_RESET                    0
#define RTAS_LOG_V6_EPOW_ACTION_WARN_COOLING             1
#define RTAS_LOG_V6_EPOW_ACTION_WARN_POWER               2
#define RTAS_LOG_V6_EPOW_ACTION_SYSTEM_SHUTDOWN          3
#define RTAS_LOG_V6_EPOW_ACTION_SYSTEM_HALT              4
#define RTAS_LOG_V6_EPOW_ACTION_MAIN_ENCLOSURE           5
#define RTAS_LOG_V6_EPOW_ACTION_POWER_OFF                7
    uint8_t event_modifier;
#define RTAS_LOG_V6_EPOW_MODIFIER_NORMAL                 1
#define RTAS_LOG_V6_EPOW_MODIFIER_ON_UPS                 2
#define RTAS_LOG_V6_EPOW_MODIFIER_CRITICAL               3
#define RTAS_LOG_V6_EPOW_MODIFIER_TEMPERATURE            4
    uint8_t extended_modifier;
#define RTAS_LOG_V6_EPOW_XMODIFIER_SYSTEM_WIDE           0
#define RTAS_LOG_V6_EPOW_XMODIFIER_PARTITION_SPECIFIC    1
    uint8_t _resv;
    uint64_t reason_code;
} QEMU_PACKED;

struct epow_log_full {
    struct rtas_error_log hdr;
    struct rtas_event_log_v6 v6hdr;
    struct rtas_event_log_v6_maina maina;
    struct rtas_event_log_v6_mainb mainb;
    struct rtas_event_log_v6_epow epow;
} QEMU_PACKED;

struct rtas_event_log_v6_hp {
#define RTAS_LOG_V6_SECTION_ID_HOTPLUG              0x4850 /* HP */
    struct rtas_event_log_v6_section_header hdr;
    uint8_t hotplug_type;
#define RTAS_LOG_V6_HP_TYPE_CPU                          1
#define RTAS_LOG_V6_HP_TYPE_MEMORY                       2
#define RTAS_LOG_V6_HP_TYPE_SLOT                         3
#define RTAS_LOG_V6_HP_TYPE_PHB                          4
#define RTAS_LOG_V6_HP_TYPE_PCI                          5
    uint8_t hotplug_action;
#define RTAS_LOG_V6_HP_ACTION_ADD                        1
#define RTAS_LOG_V6_HP_ACTION_REMOVE                     2
    uint8_t hotplug_identifier;
#define RTAS_LOG_V6_HP_ID_DRC_NAME                       1
#define RTAS_LOG_V6_HP_ID_DRC_INDEX                      2
#define RTAS_LOG_V6_HP_ID_DRC_COUNT                      3
    uint8_t reserved;
    union {
        uint32_t index;
        uint32_t count;
        char name[1];
    } drc;
} QEMU_PACKED;

struct hp_log_full {
    struct rtas_error_log hdr;
    struct rtas_event_log_v6 v6hdr;
    struct rtas_event_log_v6_maina maina;
    struct rtas_event_log_v6_mainb mainb;
    struct rtas_event_log_v6_hp hp;
} QEMU_PACKED;

#define EVENT_MASK_INTERNAL_ERRORS           0x80000000
#define EVENT_MASK_EPOW                      0x40000000
#define EVENT_MASK_HOTPLUG                   0x10000000
#define EVENT_MASK_IO                        0x08000000

#define _FDT(exp) \
    do { \
        int ret = (exp);                                           \
        if (ret < 0) {                                             \
            fprintf(stderr, "qemu: error creating device tree: %s: %s\n", \
                    #exp, fdt_strerror(ret));                      \
            exit(1);                                               \
        }                                                          \
    } while (0)

void spapr_events_fdt_skel(void *fdt, uint32_t check_exception_irq)
{
    uint32_t irq_ranges[] = {cpu_to_be32(check_exception_irq), cpu_to_be32(1)};
    uint32_t interrupts[] = {cpu_to_be32(check_exception_irq), 0};

    _FDT((fdt_begin_node(fdt, "event-sources")));

    _FDT((fdt_property(fdt, "interrupt-controller", NULL, 0)));
    _FDT((fdt_property_cell(fdt, "#interrupt-cells", 2)));
    _FDT((fdt_property(fdt, "interrupt-ranges",
                       irq_ranges, sizeof(irq_ranges))));

    _FDT((fdt_begin_node(fdt, "epow-events")));
    _FDT((fdt_property(fdt, "interrupts", interrupts, sizeof(interrupts))));
    _FDT((fdt_end_node(fdt)));

    _FDT((fdt_end_node(fdt)));
}

static void rtas_event_log_queue(int log_type, void *data, bool exception)
{
    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
    sPAPREventLogEntry *entry = g_new(sPAPREventLogEntry, 1);

    g_assert(data);
    entry->log_type = log_type;
    entry->exception = exception;
    entry->data = data;
    QTAILQ_INSERT_TAIL(&spapr->pending_events, entry, next);
}

static sPAPREventLogEntry *rtas_event_log_dequeue(uint32_t event_mask,
                                                  bool exception)
{
    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
    sPAPREventLogEntry *entry = NULL;

    /* we only queue EPOW events atm. */
    if ((event_mask & EVENT_MASK_EPOW) == 0) {
        return NULL;
    }

    QTAILQ_FOREACH(entry, &spapr->pending_events, next) {
        if (entry->exception != exception) {
            continue;
        }

        /* EPOW and hotplug events are surfaced in the same manner */
        if (entry->log_type == RTAS_LOG_TYPE_EPOW ||
            entry->log_type == RTAS_LOG_TYPE_HOTPLUG) {
            break;
        }
    }

    if (entry) {
        QTAILQ_REMOVE(&spapr->pending_events, entry, next);
    }

    return entry;
}

static bool rtas_event_log_contains(uint32_t event_mask, bool exception)
{
    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
    sPAPREventLogEntry *entry = NULL;

    /* we only queue EPOW events atm. */
    if ((event_mask & EVENT_MASK_EPOW) == 0) {
        return false;
    }

    QTAILQ_FOREACH(entry, &spapr->pending_events, next) {
        if (entry->exception != exception) {
            continue;
        }

        /* EPOW and hotplug events are surfaced in the same manner */
        if (entry->log_type == RTAS_LOG_TYPE_EPOW ||
            entry->log_type == RTAS_LOG_TYPE_HOTPLUG) {
            return true;
        }
    }

    return false;
}

static uint32_t next_plid;

static void spapr_init_v6hdr(struct rtas_event_log_v6 *v6hdr)
{
    v6hdr->b0 = RTAS_LOG_V6_B0_VALID | RTAS_LOG_V6_B0_NEW_LOG
        | RTAS_LOG_V6_B0_BIGENDIAN;
    v6hdr->b2 = RTAS_LOG_V6_B2_POWERPC_FORMAT
        | RTAS_LOG_V6_B2_LOG_FORMAT_PLATFORM_EVENT;
    v6hdr->company = cpu_to_be32(RTAS_LOG_V6_COMPANY_IBM);
}

static void spapr_init_maina(struct rtas_event_log_v6_maina *maina,
                             int section_count)
{
    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
    struct tm tm;
    int year;

    maina->hdr.section_id = cpu_to_be16(RTAS_LOG_V6_SECTION_ID_MAINA);
    maina->hdr.section_length = cpu_to_be16(sizeof(*maina));
    /* FIXME: section version, subtype and creator id? */
    spapr_rtc_read(spapr->rtc, &tm, NULL);
    year = tm.tm_year + 1900;
    maina->creation_date = cpu_to_be32((to_bcd(year / 100) << 24)
                                       | (to_bcd(year % 100) << 16)
                                       | (to_bcd(tm.tm_mon + 1) << 8)
                                       | to_bcd(tm.tm_mday));
    maina->creation_time = cpu_to_be32((to_bcd(tm.tm_hour) << 24)
                                       | (to_bcd(tm.tm_min) << 16)
                                       | (to_bcd(tm.tm_sec) << 8));
    maina->creator_id = 'H'; /* Hypervisor */
    maina->section_count = section_count;
    maina->plid = next_plid++;
}

static void spapr_powerdown_req(Notifier *n, void *opaque)
{
    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
    struct rtas_error_log *hdr;
    struct rtas_event_log_v6 *v6hdr;
    struct rtas_event_log_v6_maina *maina;
    struct rtas_event_log_v6_mainb *mainb;
    struct rtas_event_log_v6_epow *epow;
    struct epow_log_full *new_epow;

    new_epow = g_malloc0(sizeof(*new_epow));
    hdr = &new_epow->hdr;
    v6hdr = &new_epow->v6hdr;
    maina = &new_epow->maina;
    mainb = &new_epow->mainb;
    epow = &new_epow->epow;

    hdr->summary = cpu_to_be32(RTAS_LOG_VERSION_6
                               | RTAS_LOG_SEVERITY_EVENT
                               | RTAS_LOG_DISPOSITION_NOT_RECOVERED
                               | RTAS_LOG_OPTIONAL_PART_PRESENT
                               | RTAS_LOG_TYPE_EPOW);
    hdr->extended_length = cpu_to_be32(sizeof(*new_epow)
                                       - sizeof(new_epow->hdr));

    spapr_init_v6hdr(v6hdr);
    spapr_init_maina(maina, 3 /* Main-A, Main-B and EPOW */);

    mainb->hdr.section_id = cpu_to_be16(RTAS_LOG_V6_SECTION_ID_MAINB);
    mainb->hdr.section_length = cpu_to_be16(sizeof(*mainb));
    /* FIXME: section version, subtype and creator id? */
    mainb->subsystem_id = 0xa0; /* External environment */
    mainb->event_severity = 0x00; /* Informational / non-error */
    mainb->event_subtype = 0xd0; /* Normal shutdown */

    epow->hdr.section_id = cpu_to_be16(RTAS_LOG_V6_SECTION_ID_EPOW);
    epow->hdr.section_length = cpu_to_be16(sizeof(*epow));
    epow->hdr.section_version = 2; /* includes extended modifier */
    /* FIXME: section subtype and creator id? */
    epow->sensor_value = RTAS_LOG_V6_EPOW_ACTION_SYSTEM_SHUTDOWN;
    epow->event_modifier = RTAS_LOG_V6_EPOW_MODIFIER_NORMAL;
    epow->extended_modifier = RTAS_LOG_V6_EPOW_XMODIFIER_PARTITION_SPECIFIC;

    rtas_event_log_queue(RTAS_LOG_TYPE_EPOW, new_epow, true);

    qemu_irq_pulse(xics_get_qirq(spapr->icp, spapr->check_exception_irq));
}

static void spapr_hotplug_req_event(uint8_t hp_id, uint8_t hp_action,
                                    sPAPRDRConnectorType drc_type,
                                    uint32_t drc)
{
    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
    struct hp_log_full *new_hp;
    struct rtas_error_log *hdr;
    struct rtas_event_log_v6 *v6hdr;
    struct rtas_event_log_v6_maina *maina;
    struct rtas_event_log_v6_mainb *mainb;
    struct rtas_event_log_v6_hp *hp;

    new_hp = g_malloc0(sizeof(struct hp_log_full));
    hdr = &new_hp->hdr;
    v6hdr = &new_hp->v6hdr;
    maina = &new_hp->maina;
    mainb = &new_hp->mainb;
    hp = &new_hp->hp;

    hdr->summary = cpu_to_be32(RTAS_LOG_VERSION_6
                               | RTAS_LOG_SEVERITY_EVENT
                               | RTAS_LOG_DISPOSITION_NOT_RECOVERED
                               | RTAS_LOG_OPTIONAL_PART_PRESENT
                               | RTAS_LOG_INITIATOR_HOTPLUG
                               | RTAS_LOG_TYPE_HOTPLUG);
    hdr->extended_length = cpu_to_be32(sizeof(*new_hp)
                                       - sizeof(new_hp->hdr));

    spapr_init_v6hdr(v6hdr);
    spapr_init_maina(maina, 3 /* Main-A, Main-B, HP */);

    mainb->hdr.section_id = cpu_to_be16(RTAS_LOG_V6_SECTION_ID_MAINB);
    mainb->hdr.section_length = cpu_to_be16(sizeof(*mainb));
    mainb->subsystem_id = 0x80; /* External environment */
    mainb->event_severity = 0x00; /* Informational / non-error */
    mainb->event_subtype = 0x00; /* Normal shutdown */

    hp->hdr.section_id = cpu_to_be16(RTAS_LOG_V6_SECTION_ID_HOTPLUG);
    hp->hdr.section_length = cpu_to_be16(sizeof(*hp));
    hp->hdr.section_version = 1; /* includes extended modifier */
    hp->hotplug_action = hp_action;
    hp->hotplug_identifier = hp_id;

    switch (drc_type) {
    case SPAPR_DR_CONNECTOR_TYPE_PCI:
        hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_PCI;
        break;
    case SPAPR_DR_CONNECTOR_TYPE_LMB:
        hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_MEMORY;
        break;
    default:
        /* we shouldn't be signaling hotplug events for resources
         * that don't support them
         */
        g_assert(false);
        return;
    }

    if (hp_id == RTAS_LOG_V6_HP_ID_DRC_COUNT) {
        hp->drc.count = cpu_to_be32(drc);
    } else if (hp_id == RTAS_LOG_V6_HP_ID_DRC_INDEX) {
        hp->drc.index = cpu_to_be32(drc);
    }

    rtas_event_log_queue(RTAS_LOG_TYPE_HOTPLUG, new_hp, true);

    qemu_irq_pulse(xics_get_qirq(spapr->icp, spapr->check_exception_irq));
}

void spapr_hotplug_req_add_by_index(sPAPRDRConnector *drc)
{
    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
    sPAPRDRConnectorType drc_type = drck->get_type(drc);
    uint32 index = drck->get_index(drc);

    spapr_hotplug_req_event(RTAS_LOG_V6_HP_ID_DRC_INDEX,
                            RTAS_LOG_V6_HP_ACTION_ADD, drc_type, index);
}

void spapr_hotplug_req_remove_by_index(sPAPRDRConnector *drc)
{
    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
    sPAPRDRConnectorType drc_type = drck->get_type(drc);
    uint32 index = drck->get_index(drc);

    spapr_hotplug_req_event(RTAS_LOG_V6_HP_ID_DRC_INDEX,
                            RTAS_LOG_V6_HP_ACTION_REMOVE, drc_type, index);
}

void spapr_hotplug_req_add_by_count(sPAPRDRConnectorType drc_type,
                                       uint32_t count)
{
    spapr_hotplug_req_event(RTAS_LOG_V6_HP_ID_DRC_COUNT,
                            RTAS_LOG_V6_HP_ACTION_ADD, drc_type, count);
}

void spapr_hotplug_req_remove_by_count(sPAPRDRConnectorType drc_type,
                                          uint32_t count)
{
    spapr_hotplug_req_event(RTAS_LOG_V6_HP_ID_DRC_COUNT,
                            RTAS_LOG_V6_HP_ACTION_REMOVE, drc_type, count);
}

static void check_exception(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                            uint32_t token, uint32_t nargs,
                            target_ulong args,
                            uint32_t nret, target_ulong rets)
{
    uint32_t mask, buf, len, event_len;
    uint64_t xinfo;
    sPAPREventLogEntry *event;
    struct rtas_error_log *hdr;

    if ((nargs < 6) || (nargs > 7) || nret != 1) {
        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
        return;
    }

    xinfo = rtas_ld(args, 1);
    mask = rtas_ld(args, 2);
    buf = rtas_ld(args, 4);
    len = rtas_ld(args, 5);
    if (nargs == 7) {
        xinfo |= (uint64_t)rtas_ld(args, 6) << 32;
    }

    event = rtas_event_log_dequeue(mask, true);
    if (!event) {
        goto out_no_events;
    }

    hdr = event->data;
    event_len = be32_to_cpu(hdr->extended_length) + sizeof(*hdr);

    if (event_len < len) {
        len = event_len;
    }

    cpu_physical_memory_write(buf, event->data, len);
    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
    g_free(event->data);
    g_free(event);

    /* according to PAPR+, the IRQ must be left asserted, or re-asserted, if
     * there are still pending events to be fetched via check-exception. We
     * do the latter here, since our code relies on edge-triggered
     * interrupts.
     */
    if (rtas_event_log_contains(mask, true)) {
        qemu_irq_pulse(xics_get_qirq(spapr->icp, spapr->check_exception_irq));
    }

    return;

out_no_events:
    rtas_st(rets, 0, RTAS_OUT_NO_ERRORS_FOUND);
}

static void event_scan(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                       uint32_t token, uint32_t nargs,
                       target_ulong args,
                       uint32_t nret, target_ulong rets)
{
    uint32_t mask, buf, len, event_len;
    sPAPREventLogEntry *event;
    struct rtas_error_log *hdr;

    if (nargs != 4 || nret != 1) {
        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
        return;
    }

    mask = rtas_ld(args, 0);
    buf = rtas_ld(args, 2);
    len = rtas_ld(args, 3);

    event = rtas_event_log_dequeue(mask, false);
    if (!event) {
        goto out_no_events;
    }

    hdr = event->data;
    event_len = be32_to_cpu(hdr->extended_length) + sizeof(*hdr);

    if (event_len < len) {
        len = event_len;
    }

    cpu_physical_memory_write(buf, event->data, len);
    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
    g_free(event->data);
    g_free(event);
    return;

out_no_events:
    rtas_st(rets, 0, RTAS_OUT_NO_ERRORS_FOUND);
}

void spapr_events_init(sPAPRMachineState *spapr)
{
    QTAILQ_INIT(&spapr->pending_events);
    spapr->check_exception_irq = xics_alloc(spapr->icp, 0, 0, false);
    spapr->epow_notifier.notify = spapr_powerdown_req;
    qemu_register_powerdown_notifier(&spapr->epow_notifier);
    spapr_rtas_register(RTAS_CHECK_EXCEPTION, "check-exception",
                        check_exception);
    spapr_rtas_register(RTAS_EVENT_SCAN, "event-scan", event_scan);
}