Re: [Qemu-devel] [PATCH V17 06/12] quorum: Add quorum mechanism.

[Max Reitz <mreitz@redhat.com>]

On 12.02.2014 23:06, Benoît Canet wrote:
> From: Benoît Canet <benoit@irqsave.net>
>
> This patchset enable the core of the quorum mechanism.

"enables"

> The num_children reads are compared to get the majority version and if this
> version exist more than threshold time the guest won't see the error at all.

"exists", "times"

> QMP events are used to report individual driver errors or whole quorum.
> error to the management.

What is this supposed to mean?

> Use gnutls's SHA-256 to compare versions.
>
> --enable-quorum must be used to enable the feature.
>
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
>   block/Makefile.objs       |   2 +-
>   block/quorum.c            | 394 ++++++++++++++++++++++++++++++++++++++++++++++
>   configure                 |  36 +++++
>   docs/qmp/qmp-events.txt   |  36 +++++
>   include/monitor/monitor.h |   2 +
>   monitor.c                 |   2 +
>   6 files changed, 471 insertions(+), 1 deletion(-)
>
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index 716556f..425d7fb 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -3,7 +3,7 @@ block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-c
>   block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
>   block-obj-y += qed-check.o
>   block-obj-$(CONFIG_VHDX) += vhdx.o vhdx-endian.o vhdx-log.o
> -block-obj-y += quorum.o
> +block-obj-$(CONFIG_QUORUM) += quorum.o
>   block-obj-y += parallels.o blkdebug.o blkverify.o
>   block-obj-y += snapshot.o qapi.o
>   block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
> diff --git a/block/quorum.c b/block/quorum.c
> index c7a5d79..bfd8e9d 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -13,7 +13,43 @@
>    * See the COPYING file in the top-level directory.
>    */
>   
> +#include <gnutls/gnutls.h>
> +#include <gnutls/crypto.h>
>   #include "block/block_int.h"
> +#include "qapi/qmp/qjson.h"
> +
> +#define HASH_LENGTH 32
> +
> +/* This union holds a vote hash value */
> +typedef union QuorumVoteValue {
> +    char h[HASH_LENGTH];       /* SHA-256 hash */
> +    int64_t l;                 /* simpler 64 bits hash */
> +} QuorumVoteValue;
> +
> +/* A vote item */
> +typedef struct QuorumVoteItem {
> +    int index;
> +    QLIST_ENTRY(QuorumVoteItem) next;
> +} QuorumVoteItem;
> +
> +/* this structure is a vote version. A version is the set of votes sharing the
> + * same vote value.
> + * The set of votes will be tracked with the items field and its cardinality is
> + * vote_count.
> + */
> +typedef struct QuorumVoteVersion {
> +    QuorumVoteValue value;
> +    int index;
> +    int vote_count;
> +    QLIST_HEAD(, QuorumVoteItem) items;
> +    QLIST_ENTRY(QuorumVoteVersion) next;
> +} QuorumVoteVersion;
> +
> +/* this structure holds a group of vote versions together */
> +typedef struct QuorumVotes {
> +    QLIST_HEAD(, QuorumVoteVersion) vote_list;
> +    bool (*compare)(QuorumVoteValue *a, QuorumVoteValue *b);
> +} QuorumVotes;
>   
>   /* the following structure holds the state of one quorum instance */
>   typedef struct BDRVQuorumState {
> @@ -65,10 +101,14 @@ struct QuorumAIOCB {
>       int count;                  /* number of completed AIOCB */
>       int success_count;          /* number of successfully completed AIOCB */
>   
> +    QuorumVotes votes;
> +
>       bool is_read;
>       int vote_ret;
>   };
>   
> +static void quorum_vote(QuorumAIOCB *acb);
> +
>   static void quorum_aio_cancel(BlockDriverAIOCB *blockacb)
>   {
>       QuorumAIOCB *acb = container_of(blockacb, QuorumAIOCB, common);
> @@ -94,6 +134,10 @@ static void quorum_aio_finalize(QuorumAIOCB *acb)
>       BDRVQuorumState *s = acb->common.bs->opaque;
>       int i, ret = 0;
>   
> +    if (acb->vote_ret) {
> +        ret = acb->vote_ret;
> +    }
> +
>       acb->common.cb(acb->common.opaque, ret);
>   
>       if (acb->is_read) {
> @@ -107,6 +151,16 @@ static void quorum_aio_finalize(QuorumAIOCB *acb)
>       qemu_aio_release(acb);
>   }
>   
> +static bool quorum_sha256_compare(QuorumVoteValue *a, QuorumVoteValue *b)
> +{
> +    return memcmp(a->h, b->h, HASH_LENGTH);
> +}
> +
> +static bool quorum_64bits_compare(QuorumVoteValue *a, QuorumVoteValue *b)
> +{
> +    return a->l != b->l;
> +}
> +

Okay, so these functions return true if the values differ and false if 
they're equal. Not what I'd naturally assume (so you should at least 
document it), but okay. So far.

>   static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s,
>                                      BlockDriverState *bs,
>                                      QEMUIOVector *qiov,
> @@ -125,6 +179,8 @@ static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s,
>       acb->qcrs = g_new0(QuorumChildRequest, s->num_children);
>       acb->count = 0;
>       acb->success_count = 0;
> +    acb->votes.compare = quorum_sha256_compare;
> +    QLIST_INIT(&acb->votes.vote_list);
>       acb->is_read = false;
>       acb->vote_ret = 0;
>   
> @@ -137,6 +193,53 @@ static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s,
>       return acb;
>   }
>   
> +static void quorum_report_bad(QuorumAIOCB *acb, char *node_name, int ret)
> +{
> +    QObject *data;
> +    assert(node_name);
> +    data = qobject_from_jsonf("{ 'ret': %i"
> +                              ", 'node-name': \"%s\""
> +                              ", 'sector-num': %" PRId64
> +                              ", 'sectors-count': %i }",
> +                              ret,
> +                              node_name,
> +                              acb->sector_num,
> +                              acb->nb_sectors);

These non-string parameters fit on a single line, but that's a matter of 
taste.

> +    monitor_protocol_event(QEVENT_QUORUM_REPORT_BAD, data);
> +    qobject_decref(data);
> +}
> +
> +static void quorum_report_failure(QuorumAIOCB *acb)
> +{
> +    QObject *data;
> +    const char *reference = acb->common.bs->device_name[0] ?
> +                            acb->common.bs->device_name :
> +                            acb->common.bs->node_name;
> +    data = qobject_from_jsonf("{ 'reference': \"%s\""
> +                              ", 'sector-num': %" PRId64
> +                              ", 'sectors-count': %i }",
> +                              reference,
> +                              acb->sector_num,
> +                              acb->nb_sectors);

Same here.

> +    monitor_protocol_event(QEVENT_QUORUM_FAILURE, data);
> +    qobject_decref(data);
> +}
> +
> +static int quorum_vote_error(QuorumAIOCB *acb);
> +
> +static bool quorum_has_too_much_io_failed(QuorumAIOCB *acb)
> +{
> +    BDRVQuorumState *s = acb->common.bs->opaque;
> +
> +    if (acb->success_count < s->threshold) {
> +        acb->vote_ret = quorum_vote_error(acb);
> +        quorum_report_failure(acb);
> +        return true;
> +    }
> +
> +    return false;
> +}
> +
>   static void quorum_aio_cb(void *opaque, int ret)
>   {
>       QuorumChildRequest *sacb = opaque;
> @@ -147,6 +250,8 @@ static void quorum_aio_cb(void *opaque, int ret)
>       acb->count++;
>       if (ret == 0) {
>           acb->success_count++;
> +    } else {
> +        quorum_report_bad(acb, sacb->aiocb->bs->node_name, ret);
>       }
>       assert(acb->count <= s->num_children);
>       assert(acb->success_count <= s->num_children);
> @@ -154,9 +259,298 @@ static void quorum_aio_cb(void *opaque, int ret)
>           return;
>       }
>   
> +    /* Do the vote on read */
> +    if (acb->is_read) {
> +        quorum_vote(acb);
> +    } else {
> +        quorum_has_too_much_io_failed(acb);
> +    }
> +
>       quorum_aio_finalize(acb);
>   }
>   
> +static void quorum_report_bad_versions(BDRVQuorumState *s,
> +                                       QuorumAIOCB *acb,
> +                                       QuorumVoteValue *value)
> +{
> +    QuorumVoteVersion *version;
> +    QuorumVoteItem *item;
> +
> +    QLIST_FOREACH(version, &acb->votes.vote_list, next) {
> +        if (!acb->votes.compare(&version->value, value)) {
> +            continue;
> +        }
> +        QLIST_FOREACH(item, &version->items, next) {
> +            quorum_report_bad(acb, s->bs[item->index]->node_name, 0);
> +        }
> +    }
> +}
> +
> +static void quorum_copy_qiov(QEMUIOVector *dest, QEMUIOVector *source)
> +{
> +    int i;
> +    assert(dest->niov == source->niov);
> +    assert(dest->size == source->size);
> +    for (i = 0; i < source->niov; i++) {
> +        assert(dest->iov[i].iov_len == source->iov[i].iov_len);
> +        memcpy(dest->iov[i].iov_base,
> +               source->iov[i].iov_base,
> +               source->iov[i].iov_len);
> +    }
> +}
> +
> +static void quorum_count_vote(QuorumVotes *votes,
> +                              QuorumVoteValue *value,
> +                              int index)
> +{
> +    QuorumVoteVersion *v = NULL, *version = NULL;
> +    QuorumVoteItem *item;
> +
> +    /* look if we have something with this hash */
> +    QLIST_FOREACH(v, &votes->vote_list, next) {
> +        if (!votes->compare(&v->value, value)) {
> +            version = v;
> +            break;
> +        }
> +    }
> +
> +    /* It's a version not yet in the list add it */
> +    if (!version) {
> +        version = g_new0(QuorumVoteVersion, 1);
> +        QLIST_INIT(&version->items);
> +        memcpy(&version->value, value, sizeof(version->value));
> +        version->index = index;
> +        version->vote_count = 0;
> +        QLIST_INSERT_HEAD(&votes->vote_list, version, next);
> +    }
> +
> +    version->vote_count++;
> +
> +    item = g_new0(QuorumVoteItem, 1);
> +    item->index = index;
> +    QLIST_INSERT_HEAD(&version->items, item, next);
> +}
> +
> +static void quorum_free_vote_list(QuorumVotes *votes)
> +{
> +    QuorumVoteVersion *version, *next_version;
> +    QuorumVoteItem *item, *next_item;
> +
> +    QLIST_FOREACH_SAFE(version, &votes->vote_list, next, next_version) {
> +        QLIST_REMOVE(version, next);
> +        QLIST_FOREACH_SAFE(item, &version->items, next, next_item) {
> +            QLIST_REMOVE(item, next);
> +            g_free(item);
> +        }
> +        g_free(version);
> +    }
> +}
> +
> +static int quorum_compute_hash(QuorumAIOCB *acb, int i, QuorumVoteValue *hash)
> +{
> +    int j, ret;
> +    gnutls_hash_hd_t dig;
> +    QEMUIOVector *qiov = &acb->qcrs[i].qiov;
> +
> +    ret = gnutls_hash_init(&dig, GNUTLS_DIG_SHA256);
> +
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    for (j = 0; j < qiov->niov; j++) {
> +        ret = gnutls_hash(dig, qiov->iov[j].iov_base, qiov->iov[j].iov_len);
> +        if (ret < 0) {
> +            break;
> +        }
> +    }
> +
> +    gnutls_hash_deinit(dig, (void *) hash);
> +    return ret;
> +}
> +
> +static QuorumVoteVersion *quorum_get_vote_winner(QuorumVotes *votes)
> +{
> +    int max = 0;
> +    QuorumVoteVersion *candidate, *winner = NULL;
> +
> +    QLIST_FOREACH(candidate, &votes->vote_list, next) {
> +        if (candidate->vote_count > max) {
> +            max = candidate->vote_count;
> +            winner = candidate;
> +        }
> +    }
> +
> +    return winner;
> +}
> +
> +/* qemu_iovec_compare is handy for blkverify mode because it return the first

"returns"

> + * differing byte location. Yet it is handcoded to compare vectors one byte
> + * after another so it does not benefit from the libc SIMD optimizations.

Implying, the libc actually has SIMD optimizations. Last time I heard, 
repe cmpsd is as fast as SSE optimized versions at least on Sandy 
Bridge. And also implying, the compiler is unable to optimize 
qemu_iovec_compare() using SSE (Judging from how the function is 
written, my guess is it is able to).

But okay, C compilers are not everywhere as good as they are on x86, so 
I'm fine with it.

> + * quorum_iovec_compare is written for speed and should be used in the non
> + * blkverify mode of quorum.
> + */
> +static bool quorum_iovec_compare(QEMUIOVector *a, QEMUIOVector *b)
> +{
> +    int i;
> +    int result;
> +
> +    assert(a->niov == b->niov);
> +    for (i = 0; i < a->niov; i++) {
> +        assert(a->iov[i].iov_len == b->iov[i].iov_len);
> +        result = memcmp(a->iov[i].iov_base,
> +                        b->iov[i].iov_base,
> +                        a->iov[i].iov_len);
> +        if (result) {
> +            return false;
> +        }
> +    }
> +
> +    return true;
> +}

Ookay, so this function returns true if the QIOVs are equal and false if 
they differ. This behavior is exactly the opposite from what the value 
comparing functions do. I personally find this pretty confusing.

> +
> +static void GCC_FMT_ATTR(2, 3) quorum_err(QuorumAIOCB *acb,
> +                                          const char *fmt, ...)
> +{
> +    va_list ap;
> +
> +    va_start(ap, fmt);
> +    fprintf(stderr, "quorum: sector_num=%" PRId64 " nb_sectors=%d ",
> +            acb->sector_num, acb->nb_sectors);
> +    vfprintf(stderr, fmt, ap);
> +    fprintf(stderr, "\n");
> +    va_end(ap);
> +    exit(1);
> +}
> +
> +static bool quorum_compare(QuorumAIOCB *acb,
> +                           QEMUIOVector *a,
> +                           QEMUIOVector *b)
> +{
> +    BDRVQuorumState *s = acb->common.bs->opaque;
> +    ssize_t offset;
> +
> +    /* This driver will replace blkverify in this particular case */
> +    if (s->is_blkverify) {
> +        offset = qemu_iovec_compare(a, b);
> +        if (offset != -1) {
> +            quorum_err(acb, "contents mismatch in sector %" PRId64,
> +                       acb->sector_num +
> +                       (uint64_t)(offset / BDRV_SECTOR_SIZE));
> +        }
> +        return true;
> +    }
> +
> +    return quorum_iovec_compare(a, b);
> +}
> +
> +/* Do a vote to get the error code */
> +static int quorum_vote_error(QuorumAIOCB *acb)
> +{
> +    BDRVQuorumState *s = acb->common.bs->opaque;
> +    QuorumVoteVersion *winner = NULL;
> +    QuorumVotes error_votes;
> +    QuorumVoteValue result_value;
> +    int i, ret = 0;
> +    bool error = false;
> +
> +    QLIST_INIT(&error_votes.vote_list);
> +    error_votes.compare = quorum_64bits_compare;
> +
> +    for (i = 0; i < s->num_children; i++) {
> +        ret = acb->qcrs[i].ret;
> +        if (ret) {
> +            error = true;
> +            result_value.l = ret;
> +            quorum_count_vote(&error_votes, &result_value, i);
> +        }
> +    }
> +
> +    if (error) {
> +        winner = quorum_get_vote_winner(&error_votes);
> +        ret = winner->value.l;
> +    }
> +
> +    quorum_free_vote_list(&error_votes);
> +
> +    return ret;
> +}
> +
> +static void quorum_vote(QuorumAIOCB *acb)
> +{
> +    bool quorum = true;
> +    int i, j, ret;
> +    QuorumVoteValue hash;
> +    BDRVQuorumState *s = acb->common.bs->opaque;
> +    QuorumVoteVersion *winner;
> +
> +    if (quorum_has_too_much_io_failed(acb)) {
> +        return;
> +    }
> +
> +    /* get the index of the first successful read */
> +    for (i = 0; i < s->num_children; i++) {
> +        if (!acb->qcrs[i].ret) {
> +            break;
> +        }
> +    }
> +
> +    assert(i < s->num_children);
> +
> +    /* compare this read with all other successful read stoping at quorum

"reads" and "stopping"

> +     * failure
> +     */
> +    for (j = i + 1; j < s->num_children; j++) {
> +        if (acb->qcrs[j].ret) {
> +            continue;
> +        }
> +        quorum = quorum_compare(acb, &acb->qcrs[i].qiov, &acb->qcrs[j].qiov);
> +        if (!quorum) {
> +            break;
> +       }
> +    }
> +
> +    /* Every successful read agrees */
> +    if (quorum) {
> +        quorum_copy_qiov(acb->qiov, &acb->qcrs[i].qiov);
> +        return;
> +    }
> +
> +    /* compute hashs for each successful read, also store indexes */

"hashes" (by the way, I'm sorry for pointing out such mistakes only just 
know but not before)

> +    for (i = 0; i < s->num_children; i++) {
> +        if (acb->qcrs[i].ret) {
> +            continue;
> +        }
> +        ret = quorum_compute_hash(acb, i, &hash);
> +        /* if ever the hash computation failed */
> +        if (ret < 0) {
> +            acb->vote_ret = ret;
> +            goto free_exit;
> +        }
> +        quorum_count_vote(&acb->votes, &hash, i);
> +    }
> +
> +    /* vote to select the most represented version */
> +    winner = quorum_get_vote_winner(&acb->votes);
> +
> +    /* if the winner count is smaller than threshold the read fails */
> +    if (winner->vote_count < s->threshold) {
> +        quorum_report_failure(acb);
> +        acb->vote_ret = -EIO;
> +        goto free_exit;
> +    }
> +
> +    /* we have a winner: copy it */
> +    quorum_copy_qiov(acb->qiov, &acb->qcrs[winner->index].qiov);
> +
> +    /* some versions are bad print them */
> +    quorum_report_bad_versions(s, acb, &winner->value);
> +
> +free_exit:
> +    /* free lists */
> +    quorum_free_vote_list(&acb->votes);
> +}
> +
>   static BlockDriverAIOCB *quorum_aio_readv(BlockDriverState *bs,
>                                            int64_t sector_num,
>                                            QEMUIOVector *qiov,
> diff --git a/configure b/configure
> index 5b20ce6..11f0a3a 100755
> --- a/configure
> +++ b/configure
> @@ -264,6 +264,7 @@ gtkabi="2.0"
>   tpm="no"
>   libssh2=""
>   vhdx=""
> +quorum="no"
>   
>   # parse CC options first
>   for opt do
> @@ -1005,6 +1006,10 @@ for opt do
>     ;;
>     --disable-vhdx) vhdx="no"
>     ;;
> +  --disable-quorum) quorum="no"
> +  ;;
> +  --enable-quorum) quorum="yes"
> +  ;;
>     *) echo "ERROR: unknown option $opt"; show_help="yes"
>     ;;
>     esac
> @@ -1261,6 +1266,8 @@ Advanced options (experts only):
>     --enable-libssh2         enable ssh block device support
>     --disable-vhdx           disables support for the Microsoft VHDX image format
>     --enable-vhdx            enable support for the Microsoft VHDX image format
> +  --disable-quorum         disable quorum block filter support
> +  --enable-quorum          enable quorum block filter support
>   
>   NOTE: The object files are built at the place where configure is launched
>   EOF
> @@ -1930,6 +1937,30 @@ EOF
>   fi
>   
>   ##########################################
> +# Quorum probe (check for gnutls)
> +if test "$quorum" != "no" ; then
> +cat > $TMPC <<EOF
> +#include <gnutls/gnutls.h>
> +#include <gnutls/crypto.h>
> +int main(void) {char data[4096], digest[32];
> +gnutls_hash_fast(GNUTLS_DIG_SHA256, data, 4096, digest);
> +return 0;
> +}
> +EOF
> +quorum_tls_cflags=`$pkg_config --cflags gnutls 2> /dev/null`
> +quorum_tls_libs=`$pkg_config --libs gnutls 2> /dev/null`
> +if compile_prog "$quorum_tls_cflags" "$quorum_tls_libs" ; then
> +  qcow_tls=yes
> +  libs_softmmu="$quorum_tls_libs $libs_softmmu"
> +  libs_tools="$quorum_tls_libs $libs_softmmu"
> +  QEMU_CFLAGS="$QEMU_CFLAGS $quorum_tls_cflags"
> +else
> +  echo "gnutls > 2.10.0 required to compile Quorum"
> +  exit 1
> +fi
> +fi
> +
> +##########################################
>   # VNC SASL detection
>   if test "$vnc" = "yes" -a "$vnc_sasl" != "no" ; then
>     cat > $TMPC <<EOF
> @@ -3865,6 +3896,7 @@ echo "libssh2 support   $libssh2"
>   echo "TPM passthrough   $tpm_passthrough"
>   echo "QOM debugging     $qom_cast_debug"
>   echo "vhdx              $vhdx"
> +echo "Quorum            $quorum"
>   
>   if test "$sdl_too_old" = "yes"; then
>   echo "-> Your SDL version is too old - please upgrade to have SDL support"
> @@ -4267,6 +4299,10 @@ if test "$libssh2" = "yes" ; then
>     echo "CONFIG_LIBSSH2=y" >> $config_host_mak
>   fi
>   
> +if test "$quorum" = "yes" ; then
> +  echo "CONFIG_QUORUM=y" >> $config_host_mak
> +fi
> +
>   if test "$virtio_blk_data_plane" = "yes" ; then
>     echo 'CONFIG_VIRTIO_BLK_DATA_PLANE=$(CONFIG_VIRTIO)' >> $config_host_mak
>   fi
> diff --git a/docs/qmp/qmp-events.txt b/docs/qmp/qmp-events.txt
> index a378c87..00f9515 100644
> --- a/docs/qmp/qmp-events.txt
> +++ b/docs/qmp/qmp-events.txt
> @@ -500,3 +500,39 @@ Example:
>   
>   Note: If action is "reset", "shutdown", or "pause" the WATCHDOG event is
>   followed respectively by the RESET, SHUTDOWN, or STOP events.
> +
> +QUORUM_FAILURE
> +--------------
> +
> +Emitted by the Quorum block driver if it fails to establish a quorum.
> +
> +Data:
> +
> +- "reference":    device name if defined else node name.
> +- "sector-num":   Number of the first sector of the failed read operation.
> +- "sector-count": Failed read operation sector count.
> +
> +Example:
> +
> +{ "event": "QUORUM_FAILURE",
> +     "data": { "reference": "usr1", "sector-num": 345435, "sector-count": 5 },
> +     "timestamp": { "seconds": 1344522075, "microseconds": 745528 } }
> +
> +QUORUM_REPORT_BAD
> +-----------------
> +
> +Emitted to report a corruption of a Quorum file.
> +
> +Data:
> +
> +- "ret":          The IO return code.
> +- "node-name":    The graph node name of the block driver state.
> +- "sector-num":   Number of the first sector of the failed read operation.
> +- "sector-count": Failed read operation sector count.
> +
> +Example:
> +
> +{ "event": "QUORUM_REPORT_BAD",
> +     "data": { "ret": 0, "node-name": "1.raw", "sector-num": 345435,
> +               "sector-count": 5 },
> +     "timestamp": { "seconds": 1344522075, "microseconds": 745528 } }
> diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> index 7e5f752..a49ea11 100644
> --- a/include/monitor/monitor.h
> +++ b/include/monitor/monitor.h
> @@ -49,6 +49,8 @@ typedef enum MonitorEvent {
>       QEVENT_SPICE_MIGRATE_COMPLETED,
>       QEVENT_GUEST_PANICKED,
>       QEVENT_BLOCK_IMAGE_CORRUPTED,
> +    QEVENT_QUORUM_FAILURE,
> +    QEVENT_QUORUM_REPORT_BAD,
>   
>       /* Add to 'monitor_event_names' array in monitor.c when
>        * defining new events here */
> diff --git a/monitor.c b/monitor.c
> index b1ea262..81ffa0f 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -507,6 +507,8 @@ static const char *monitor_event_names[] = {
>       [QEVENT_SPICE_MIGRATE_COMPLETED] = "SPICE_MIGRATE_COMPLETED",
>       [QEVENT_GUEST_PANICKED] = "GUEST_PANICKED",
>       [QEVENT_BLOCK_IMAGE_CORRUPTED] = "BLOCK_IMAGE_CORRUPTED",
> +    [QEVENT_QUORUM_FAILURE] = "QUORUM_FAILURE",
> +    [QEVENT_QUORUM_REPORT_BAD] = "QUORUM_REPORT_BAD",
>   };
>   QEMU_BUILD_BUG_ON(ARRAY_SIZE(monitor_event_names) != QEVENT_MAX)
>