Re: [Qemu-devel] [PATCH v6] net: add support of mac-programming over macvtap in QEMU side

[Michael S. Tsirkin]

On Mon, Jun 17, 2013 at 09:30:42AM -0400, Luiz Capitulino wrote:
> On Mon, 17 Jun 2013 16:21:31 +0300
> "Michael S. Tsirkin" <address@hidden> wrote:
> 
> > On Mon, Jun 17, 2013 at 09:11:27AM -0400, Luiz Capitulino wrote:
> > > On Fri, 14 Jun 2013 15:45:52 +0800
> > > Amos Kong <address@hidden> wrote:
> > > 
> > > > Currently macvtap based macvlan device is working in promiscuous
> > > > mode, we want to implement mac-programming over macvtap through
> > > > Libvirt for better performance.
> > > > 
> > > > Design:
> > > >  QEMU notifies Libvirt when rx-filter config is changed in guest,
> > > >  then Libvirt query the rx-filter information by a monitor command,
> > > >  and sync the change to macvtap device. Related rx-filter config
> > > >  of the nic contains main mac, rx-mode items and vlan table.
> > > > 
> > > > This patch adds a QMP event to notify management of rx-filter change,
> > > > and adds a monitor command for management to query rx-filter
> > > > information.
> > > > 
> > > > Test:
> > > >  If we repeatedly add/remove vlan, and change macaddr of vlan
> > > >  interfaces in guest by a loop script.
> > > > 
> > > > Result:
> > > >  The events will flood the QMP client(management), management takes
> > > >  too much resource to process the events.
> > > > 
> > > >  Event_throttle API (set rate to 1 ms) can avoid the events to flood
> > > 
> > > I doubt this is a valid value. Today, the three events that use the event
> > > throttle API set the delay rate to 1000 ms.
> > > 
> > > >  QMP client, but it could cause an unexpected delay (~1ms), guests
> > > >  guests normally expect rx-filter updates immediately.
> > > 
> > > What you mean by "immediately"? There's a round-trip to the host plus
> > > all the stuff QEMU will execute to fulfil the request. And how did you
> > > measure this, btw?
> > > 
> > > What you have to do is is to measure your test-case in three different
> > > scenarios:
> > > 
> > >  1. Against upstream QEMU (ie. no patches)
> > >  2. With the event throttle API
> > >  3. With this patch
> > > 
> > > Only then you'll be able which is better.
> > 
> > 
> > I doubt there's a lot of value in splitting this patch in two and
> > testing whether we can reproduce any problems with a partial patch. 
> 
> I didn't suggest that. Actually, I didn't even talk about code.
>
> > The
> > problem of management not keeping up with event flood triggered by mac
> > updates by guest might be purely theoretical,
> 
> That's not the problem the flag thing is trying to solve. We have the
> event throttle API for that. What the flag is trying to solve is _guest_
> latency due to event generation and it's not clear at all if this is a real
> problem.
> 
> > but a robust solution that
> > does not have theoretical holes makes me sleep better at night, and it's a
> > trivial amount of code.
> 
> It has the drawback of coupling the query command with the event.

What specifically is the problem?

I only see a fix for a problem, that might be theoretical, but I'm
happier knowing I don't need to worry about it.

> IMO, such
> a coupling has to be justified with real data.

It's a quality of implementation issue.

No spec says that you should not delay RX filter updates for a very long
time (yes 1000ms is very long), but if a NIC does it it's a low quality
NIC, and it will cause trouble in the field.

I don't think we need to spend time proving that with real data, it's just
obvious.

> > 
> > So
> > 
> > Acked-by: Michael S. Tsirkin <address@hidden>
> > 
> > Any enhancements can be implemented
> > by additional patches, to be applied on top.
> > 
> > > > 
> > > >  So we use a flag for each nic to avoid events flooding, the event
> > > >  is emitted once until the query command is executed. The flag
> > > >  implementation could not introduce unexpected delay.
> > > > 
> > > > There maybe exist an uncontrollable delay if we let Libvirt do the
> > > > real change, guests normally expect rx-filter updates immediately.
> > > > But it's another separate issue, we can investigate it when the
> > > > work in Libvirt side is done.
> > > > 
> > > > Signed-off-by: Amos Kong <address@hidden>
> > > > ---
> > > > v2: add argument to filter mac-table info of single nic (Stefan)
> > > >     update the document, add event notification
> > > > v3: rename to rx-filter, add main mac, avoid events flooding (MST)
> > > >     fix error process (Stefan), fix qmp interface (Eric)
> > > > v4: process qerror in hmp, cleanup (Luiz)
> > > >     set flag for each device, add device path in event, add
> > > >     helper for g_strdup_printf (MST)
> > > >     fix qmp document (Eric)
> > > > v5: add path in doc, define notify flag to unsigned (Eric)
> > > >     add vlan table (Jason), drop monitor cmd
> > > > v6: return vids list, add test results/analysis to commitlog
> > > > ---
> > > >  QMP/qmp-events.txt        |  17 ++++++++
> > > >  hw/net/virtio-net.c       | 108 
> > > > ++++++++++++++++++++++++++++++++++++++++++++++
> > > >  include/monitor/monitor.h |   1 +
> > > >  include/net/net.h         |   3 ++
> > > >  monitor.c                 |   1 +
> > > >  net/net.c                 |  47 ++++++++++++++++++++
> > > >  qapi-schema.json          |  75 ++++++++++++++++++++++++++++++++
> > > >  qmp-commands.hx           |  63 +++++++++++++++++++++++++++
> > > >  8 files changed, 315 insertions(+)
> > > > 
> > > > diff --git a/QMP/qmp-events.txt b/QMP/qmp-events.txt
> > > > index 24e804e9..39b6016 100644
> > > > --- a/QMP/qmp-events.txt
> > > > +++ b/QMP/qmp-events.txt
> > > > @@ -172,6 +172,23 @@ Data:
> > > >    },
> > > >    "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }
> > > >  
> > > > +NIC_RX_FILTER_CHANGED
> > > > +-----------------
> > > > +
> > > > +The event is emitted once until the query command is executed,
> > > > +the first event will always be emitted.
> > > > +
> > > > +Data:
> > > > +
> > > > +- "name": net client name (json-string)
> > > > +- "path": device path (json-string)
> > > > +
> > > > +{ "event": "NIC_RX_FILTER_CHANGED",
> > > > +  "data": { "name": "vnet0",
> > > > +            "path": "/machine/peripheral/vnet0/virtio-backend" },
> > > > +  "timestamp": { "seconds": 1368697518, "microseconds": 326866 } }
> > > > +}
> > > > +
> > > >  RESET
> > > >  -----
> > > >  
> > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> > > > index 1ea9556..4137959 100644
> > > > --- a/hw/net/virtio-net.c
> > > > +++ b/hw/net/virtio-net.c
> > > > @@ -21,6 +21,8 @@
> > > >  #include "hw/virtio/virtio-net.h"
> > > >  #include "net/vhost_net.h"
> > > >  #include "hw/virtio/virtio-bus.h"
> > > > +#include "qapi/qmp/qjson.h"
> > > > +#include "monitor/monitor.h"
> > > >  
> > > >  #define VIRTIO_NET_VM_VERSION    11
> > > >  
> > > > @@ -192,6 +194,100 @@ static void 
> > > > virtio_net_set_link_status(NetClientState *nc)
> > > >      virtio_net_set_status(vdev, vdev->status);
> > > >  }
> > > >  
> > > > +static void rxfilter_notify(NetClientState *nc)
> > > > +{
> > > > +    QObject *event_data;
> > > > +    VirtIONet *n = qemu_get_nic_opaque(nc);
> > > > +
> > > > +    if (nc->rxfilter_notify_enabled) {
> > > > +        event_data = qobject_from_jsonf("{ 'name': %s, 'path': %s }",
> > > > +                           n->netclient_name,
> > > > +                           object_get_canonical_path(OBJECT(n->qdev)));
> > > > +        monitor_protocol_event(QEVENT_NIC_RX_FILTER_CHANGED, 
> > > > event_data);
> > > > +        qobject_decref(event_data);
> > > > +
> > > > +        /* disable event notification to avoid events flooding */
> > > > +        nc->rxfilter_notify_enabled = 0;
> > > > +    }
> > > > +}
> > > > +
> > > > +static char *mac_strdup_printf(const uint8_t *mac)
> > > > +{
> > > > +    return g_strdup_printf("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x", mac[0],
> > > > +                            mac[1], mac[2], mac[3], mac[4], mac[5]);
> > > > +}
> > > > +
> > > > +static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc)
> > > > +{
> > > > +    VirtIONet *n = qemu_get_nic_opaque(nc);
> > > > +    RxFilterInfo *info;
> > > > +    strList *str_list = NULL;
> > > > +    strList *entry;
> > > > +    intList *int_list = NULL;
> > > > +    intList *int_entry;
> > > > +    int i, j;
> > > > +
> > > > +    info = g_malloc0(sizeof(*info));
> > > > +    info->name = g_strdup(nc->name);
> > > > +    info->promiscuous = n->promisc;
> > > > +
> > > > +    if (n->nouni) {
> > > > +        info->unicast = RX_STATE_NONE;
> > > > +    } else if (n->alluni) {
> > > > +        info->unicast = RX_STATE_ALL;
> > > > +    } else {
> > > > +        info->unicast = RX_STATE_NORMAL;
> > > > +    }
> > > > +
> > > > +    if (n->nomulti) {
> > > > +        info->multicast = RX_STATE_NONE;
> > > > +    } else if (n->allmulti) {
> > > > +        info->multicast = RX_STATE_ALL;
> > > > +    } else {
> > > > +        info->multicast = RX_STATE_NORMAL;
> > > > +    }
> > > > +
> > > > +    info->broadcast_allowed = n->nobcast;
> > > > +    info->multicast_overflow = n->mac_table.multi_overflow;
> > > > +    info->unicast_overflow = n->mac_table.uni_overflow;
> > > > +
> > > > +    info->main_mac = mac_strdup_printf(n->mac);
> > > > +
> > > > +    for (i = 0; i < n->mac_table.first_multi; i++) {
> > > > +        entry = g_malloc0(sizeof(*entry));
> > > > +        entry->value = mac_strdup_printf(n->mac_table.macs + i * 
> > > > ETH_ALEN);
> > > > +        entry->next = str_list;
> > > > +        str_list = entry;
> > > > +    }
> > > > +    info->unicast_table = str_list;
> > > > +
> > > > +    str_list = NULL;
> > > > +    for (i = n->mac_table.first_multi; i < n->mac_table.in_use; i++) {
> > > > +        entry = g_malloc0(sizeof(*entry));
> > > > +        entry->value = mac_strdup_printf(n->mac_table.macs + i * 
> > > > ETH_ALEN);
> > > > +        entry->next = str_list;
> > > > +        str_list = entry;
> > > > +    }
> > > > +    info->multicast_table = str_list;
> > > > +
> > > > +    for (i = 0; i < MAX_VLAN >> 5; i++) {
> > > > +        for (j = 0; n->vlans[i] && j < 0x1f; j++) {
> > > > +            if (n->vlans[i] & (1U << j)) {
> > > > +                int_entry = g_malloc0(sizeof(*int_entry));
> > > > +                int_entry->value = (i << 5) + j;
> > > > +                int_entry->next = int_list;
> > > > +                int_list = int_entry;
> > > > +            }
> > > > +        }
> > > > +    }
> > > > +    info->vlan_table = int_list;
> > > > +
> > > > +    /* enable event notification after query */
> > > > +    nc->rxfilter_notify_enabled = 1;
> > > > +
> > > > +    return info;
> > > > +}
> > > > +
> > > >  static void virtio_net_reset(VirtIODevice *vdev)
> > > >  {
> > > >      VirtIONet *n = VIRTIO_NET(vdev);
> > > > @@ -420,6 +516,7 @@ static int virtio_net_handle_rx_mode(VirtIONet *n, 
> > > > uint8_t cmd,
> > > >  {
> > > >      uint8_t on;
> > > >      size_t s;
> > > > +    NetClientState *nc = qemu_get_queue(n->nic);
> > > >  
> > > >      s = iov_to_buf(iov, iov_cnt, 0, &on, sizeof(on));
> > > >      if (s != sizeof(on)) {
> > > > @@ -442,6 +539,8 @@ static int virtio_net_handle_rx_mode(VirtIONet *n, 
> > > > uint8_t cmd,
> > > >          return VIRTIO_NET_ERR;
> > > >      }
> > > >  
> > > > +    rxfilter_notify(nc);
> > > > +
> > > >      return VIRTIO_NET_OK;
> > > >  }
> > > >  
> > > > @@ -487,6 +586,7 @@ static int virtio_net_handle_mac(VirtIONet *n, 
> > > > uint8_t cmd,
> > > >  {
> > > >      struct virtio_net_ctrl_mac mac_data;
> > > >      size_t s;
> > > > +    NetClientState *nc = qemu_get_queue(n->nic);
> > > >  
> > > >      if (cmd == VIRTIO_NET_CTRL_MAC_ADDR_SET) {
> > > >          if (iov_size(iov, iov_cnt) != sizeof(n->mac)) {
> > > > @@ -495,6 +595,8 @@ static int virtio_net_handle_mac(VirtIONet *n, 
> > > > uint8_t cmd,
> > > >          s = iov_to_buf(iov, iov_cnt, 0, &n->mac, sizeof(n->mac));
> > > >          assert(s == sizeof(n->mac));
> > > >          qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
> > > > +        rxfilter_notify(nc);
> > > > +
> > > >          return VIRTIO_NET_OK;
> > > >      }
> > > >  
> > > > @@ -559,6 +661,8 @@ static int virtio_net_handle_mac(VirtIONet *n, 
> > > > uint8_t cmd,
> > > >          n->mac_table.multi_overflow = 1;
> > > >      }
> > > >  
> > > > +    rxfilter_notify(nc);
> > > > +
> > > >      return VIRTIO_NET_OK;
> > > >  }
> > > >  
> > > > @@ -567,6 +671,7 @@ static int virtio_net_handle_vlan_table(VirtIONet 
> > > > *n, uint8_t cmd,
> > > >  {
> > > >      uint16_t vid;
> > > >      size_t s;
> > > > +    NetClientState *nc = qemu_get_queue(n->nic);
> > > >  
> > > >      s = iov_to_buf(iov, iov_cnt, 0, &vid, sizeof(vid));
> > > >      vid = lduw_p(&vid);
> > > > @@ -584,6 +689,8 @@ static int virtio_net_handle_vlan_table(VirtIONet 
> > > > *n, uint8_t cmd,
> > > >      else
> > > >          return VIRTIO_NET_ERR;
> > > >  
> > > > +    rxfilter_notify(nc);
> > > > +
> > > >      return VIRTIO_NET_OK;
> > > >  }
> > > >  
> > > > @@ -1312,6 +1419,7 @@ static NetClientInfo net_virtio_info = {
> > > >      .receive = virtio_net_receive,
> > > >          .cleanup = virtio_net_cleanup,
> > > >      .link_status_changed = virtio_net_set_link_status,
> > > > +    .query_rx_filter = virtio_net_query_rxfilter,
> > > >  };
> > > >  
> > > >  static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int 
> > > > idx)
> > > > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> > > > index 1a6cfcf..1942cc4 100644
> > > > --- a/include/monitor/monitor.h
> > > > +++ b/include/monitor/monitor.h
> > > > @@ -41,6 +41,7 @@ typedef enum MonitorEvent {
> > > >      QEVENT_BLOCK_JOB_READY,
> > > >      QEVENT_DEVICE_DELETED,
> > > >      QEVENT_DEVICE_TRAY_MOVED,
> > > > +    QEVENT_NIC_RX_FILTER_CHANGED,
> > > >      QEVENT_SUSPEND,
> > > >      QEVENT_SUSPEND_DISK,
> > > >      QEVENT_WAKEUP,
> > > > diff --git a/include/net/net.h b/include/net/net.h
> > > > index 43d85a1..30e4b04 100644
> > > > --- a/include/net/net.h
> > > > +++ b/include/net/net.h
> > > > @@ -49,6 +49,7 @@ typedef ssize_t (NetReceiveIOV)(NetClientState *, 
> > > > const struct iovec *, int);
> > > >  typedef void (NetCleanup) (NetClientState *);
> > > >  typedef void (LinkStatusChanged)(NetClientState *);
> > > >  typedef void (NetClientDestructor)(NetClientState *);
> > > > +typedef RxFilterInfo *(QueryRxFilter)(NetClientState *);
> > > >  
> > > >  typedef struct NetClientInfo {
> > > >      NetClientOptionsKind type;
> > > > @@ -59,6 +60,7 @@ typedef struct NetClientInfo {
> > > >      NetCanReceive *can_receive;
> > > >      NetCleanup *cleanup;
> > > >      LinkStatusChanged *link_status_changed;
> > > > +    QueryRxFilter *query_rx_filter;
> > > >      NetPoll *poll;
> > > >  } NetClientInfo;
> > > >  
> > > > @@ -74,6 +76,7 @@ struct NetClientState {
> > > >      unsigned receive_disabled : 1;
> > > >      NetClientDestructor *destructor;
> > > >      unsigned int queue_index;
> > > > +    unsigned rxfilter_notify_enabled:1;
> > > >  };
> > > >  
> > > >  typedef struct NICState {
> > > > diff --git a/monitor.c b/monitor.c
> > > > index 017411f..3b8117c 100644
> > > > --- a/monitor.c
> > > > +++ b/monitor.c
> > > > @@ -490,6 +490,7 @@ static const char *monitor_event_names[] = {
> > > >      [QEVENT_BLOCK_JOB_READY] = "BLOCK_JOB_READY",
> > > >      [QEVENT_DEVICE_DELETED] = "DEVICE_DELETED",
> > > >      [QEVENT_DEVICE_TRAY_MOVED] = "DEVICE_TRAY_MOVED",
> > > > +    [QEVENT_NIC_RX_FILTER_CHANGED] = "NIC_RX_FILTER_CHANGED",
> > > >      [QEVENT_SUSPEND] = "SUSPEND",
> > > >      [QEVENT_SUSPEND_DISK] = "SUSPEND_DISK",
> > > >      [QEVENT_WAKEUP] = "WAKEUP",
> > > > diff --git a/net/net.c b/net/net.c
> > > > index 43a74e4..33abffe 100644
> > > > --- a/net/net.c
> > > > +++ b/net/net.c
> > > > @@ -961,6 +961,53 @@ void print_net_client(Monitor *mon, NetClientState 
> > > > *nc)
> > > >                     nc->info_str);
> > > >  }
> > > >  
> > > > +RxFilterInfoList *qmp_query_rx_filter(bool has_name, const char *name,
> > > > +                                      Error **errp)
> > > > +{
> > > > +    NetClientState *nc;
> > > > +    RxFilterInfoList *filter_list = NULL, *last_entry = NULL;
> > > > +
> > > > +    QTAILQ_FOREACH(nc, &net_clients, next) {
> > > > +        RxFilterInfoList *entry;
> > > > +        RxFilterInfo *info;
> > > > +
> > > > +        /* only query rx-filter information of nic */
> > > > +        if (nc->info->type != NET_CLIENT_OPTIONS_KIND_NIC) {
> > > > +            continue;
> > > > +        }
> > > > +        if (has_name && strcmp(nc->name, name) != 0) {
> > > > +            continue;
> > > > +        }
> > > > +
> > > > +        if (nc->info->query_rx_filter) {
> > > > +            info = nc->info->query_rx_filter(nc);
> > > > +            entry = g_malloc0(sizeof(*entry));
> > > > +            entry->value = info;
> > > > +
> > > > +            if (!filter_list) {
> > > > +                filter_list = entry;
> > > > +            } else {
> > > > +                last_entry->next = entry;
> > > > +            }
> > > > +            last_entry = entry;
> > > > +        } else if (has_name) {
> > > > +            error_setg(errp, "net client(%s) doesn't support"
> > > > +                       " rx-filter querying", name);
> > > > +            break;
> > > > +        }
> > > > +    }
> > > > +
> > > > +    if (filter_list == NULL && !error_is_set(errp)) {
> > > > +        if (has_name) {
> > > > +            error_setg(errp, "invalid net client name: %s", name);
> > > > +        } else {
> > > > +            error_setg(errp, "no net client supports rx-filter 
> > > > querying");
> > > > +        }
> > > > +    }
> > > > +
> > > > +    return filter_list;
> > > > +}
> > > > +
> > > >  void do_info_network(Monitor *mon, const QDict *qdict)
> > > >  {
> > > >      NetClientState *nc, *peer;
> > > > diff --git a/qapi-schema.json b/qapi-schema.json
> > > > index 5ad6894..a69dc17 100644
> > > > --- a/qapi-schema.json
> > > > +++ b/qapi-schema.json
> > > > @@ -3624,3 +3624,78 @@
> > > >              '*cpuid-input-ecx': 'int',
> > > >              'cpuid-register': 'X86CPURegister32',
> > > >              'features': 'int' } }
> > > > +
> > > > +##
> > > > +# @RxState:
> > > > +#
> > > > +# Packets receiving state
> > > > +#
> > > > +# @normal: filter assigned packets according to the mac-table
> > > > +#
> > > > +# @none: don't receive any assigned packet
> > > > +#
> > > > +# @all: receive all assigned packets
> > > > +#
> > > > +##
> > > > +{ 'enum': 'RxState', 'data': [ 'normal', 'none', 'all' ] }
> > > > +
> > > > +##
> > > > +# @RxFilterInfo:
> > > > +#
> > > > +# Rx-filter information for a nic.
> > > > +#
> > > > +# @name: net client name
> > > > +#
> > > > +# @promiscuous: whether promiscuous mode is enabled
> > > > +#
> > > > +# @multicast: multicast receive state
> > > > +#
> > > > +# @unicast: unicast receive state
> > > > +#
> > > > +# @broadcast-allowed: whether to receive broadcast
> > > > +#
> > > > +# @multicast-overflow: multicast table is overflowed or not
> > > > +#
> > > > +# @unicast-overflow: unicast table is overflowed or not
> > > > +#
> > > > +# @main-mac: the main macaddr string
> > > > +#
> > > > +# @vlan-table: a list of active vlan id
> > > > +#
> > > > +# @unicast-table: a list of unicast macaddr string
> > > > +#
> > > > +# @multicast-table: a list of multicast macaddr string
> > > > +#
> > > > +# Since 1.6
> > > > +##
> > > > +
> > > > +{ 'type': 'RxFilterInfo',
> > > > +  'data': {
> > > > +    'name':               'str',
> > > > +    'promiscuous':        'bool',
> > > > +    'multicast':          'RxState',
> > > > +    'unicast':            'RxState',
> > > > +    'broadcast-allowed':  'bool',
> > > > +    'multicast-overflow': 'bool',
> > > > +    'unicast-overflow':   'bool',
> > > > +    'main-mac':           'str',
> > > > +    'vlan-table':         ['int'],
> > > > +    'unicast-table':      ['str'],
> > > > +    'multicast-table':    ['str'] }}
> > > > +
> > > > +##
> > > > +# @query-rx-filter:
> > > > +#
> > > > +# Return rx-filter information for all nics (or for the given nic).
> > > > +#
> > > > +# @name: #optional net client name
> > > > +#
> > > > +# Returns: list of @RxFilterInfo for all nics (or for the given nic).
> > > > +#          Returns an error if the given @name doesn't exist, or given
> > > > +#          nic doesn't support rx-filter querying, or no net client
> > > > +#          supports rx-filter querying
> > > > +#
> > > > +# Since: 1.6
> > > > +##
> > > > +{ 'command': 'query-rx-filter', 'data': { '*name': 'str' },
> > > > +  'returns': ['RxFilterInfo'] }
> > > > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > > > index 8cea5e5..aa00a94 100644
> > > > --- a/qmp-commands.hx
> > > > +++ b/qmp-commands.hx
> > > > @@ -2997,3 +2997,66 @@ Example:
> > > >  <- { "return": {} }
> > > >  
> > > >  EQMP
> > > > +    {
> > > > +        .name       = "query-rx-filter",
> > > > +        .args_type  = "name:s?",
> > > > +        .mhandler.cmd_new = qmp_marshal_input_query_rx_filter,
> > > > +    },
> > > > +
> > > > +SQMP
> > > > +query-rx-filter
> > > > +---------------
> > > > +
> > > > +Show rx-filter information.
> > > > +
> > > > +Returns a json-array of rx-filter information for all nics (or for the
> > > > +given nic), returning an error if the given nic doesn't exist, or
> > > > +given nic doesn't support rx-filter querying, or no net client
> > > > +supports rx-filter querying.
> > > > +
> > > > +The query will clear the event notification flag of each nic, then qemu
> > > > +will start to emit event to QMP monitor.
> > > > +
> > > > +Each array entry contains the following:
> > > > +
> > > > +- "name": net client name (json-string)
> > > > +- "promiscuous": promiscuous mode is enabled (json-bool)
> > > > +- "multicast": multicast receive state (one of 'normal', 'none', 'all')
> > > > +- "unicast": unicast receive state  (one of 'normal', 'none', 'all')
> > > > +- "broadcast-allowed": allow to receive broadcast (json-bool)
> > > > +- "multicast-overflow": multicast table is overflowed (json-bool)
> > > > +- "unicast-overflow": unicast table is overflowed (json-bool)
> > > > +- "main-mac": main macaddr string (json-string)
> > > > +- "vlan-table": a json-array of active vlan id
> > > > +- "unicast-table": a json-array of unicast macaddr string
> > > > +- "multicast-table": a json-array of multicast macaddr string
> > > > +
> > > > +Example:
> > > > +
> > > > +-> { "execute": "query-rx-filter", "arguments": { "name": "vnet0" } }
> > > > +<- { "return": [
> > > > +        {
> > > > +            "promiscuous": true,
> > > > +            "name": "vnet0",
> > > > +            "main-mac": "52:54:00:12:34:56",
> > > > +            "unicast": "normal",
> > > > +            "vlan-table": [
> > > > +                4,
> > > > +                0
> > > > +            ],
> > > > +            "unicast-table": [
> > > > +            ],
> > > > +            "multicast": "normal",
> > > > +            "multicast-overflow": false,
> > > > +            "unicast-overflow": false,
> > > > +            "multicast-table": [
> > > > +                "01:00:5e:00:00:01",
> > > > +                "33:33:00:00:00:01",
> > > > +                "33:33:ff:12:34:56"
> > > > +            ],
> > > > +            "broadcast-allowed": false
> > > > +        }
> > > > +      ]
> > > > +   }
> > > > +
> > > > +EQMP
> >