Re: [Qemu-devel] [PATCH] virtio-net: consolidate guest announcement with qemu_announce_self

[Vlad Yasevich]

On 03/29/2017 04:35 PM, Michael S. Tsirkin wrote:
> On Wed, Mar 29, 2017 at 04:19:50PM -0400, Vladislav Yasevich wrote:
>> virtio announcements seem to run on its own timer with it's own
>> repetition loop and are invoked separately from qemu_announce_self.
>> This patch consolidates announcements into a single location and
>> allows other nics to provide it's own
> 
> their own
> 
>> announcement capabilities, if
>> necessary.
>>
>> This is also usefull
> 
> or useful?
> 
>> in support of exposing qemu_announce_self through
>> qmp/hmp.
> 
> I'm guessing this is the real reason for the change.
> How is it helpful for that? Pls clarify in the commit log.

Ok

> 
>> Signed-off-by: Vladislav Yasevich <address@hidden>
>> ---
>>  hw/net/virtio-net.c            | 30 ++++++++----------------------
>>  include/hw/virtio/virtio-net.h |  2 --
>>  include/net/net.h              |  2 ++
>>  migration/savevm.c             |  6 ++++++
>>  4 files changed, 16 insertions(+), 24 deletions(-)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index c321680..6e9ce4f 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -110,14 +110,16 @@ static bool virtio_net_started(VirtIONet *n, uint8_t 
>> status)
>>          (n->status & VIRTIO_NET_S_LINK_UP) && vdev->vm_running;
>>  }
>>  
>> -static void virtio_net_announce_timer(void *opaque)
>> +static void virtio_net_announce(NetClientState *nc)
>>  {
>> -    VirtIONet *n = opaque;
>> +    VirtIONet *n = qemu_get_nic_opaque(nc);
>>      VirtIODevice *vdev = VIRTIO_DEVICE(n);
>>  
>> -    n->announce_counter--;
>> -    n->status |= VIRTIO_NET_S_ANNOUNCE;
>> -    virtio_notify_config(vdev);
>> +    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
>> +        virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
>> +            n->status |= VIRTIO_NET_S_ANNOUNCE;
>> +            virtio_notify_config(vdev);
>> +    }
>>  }
>>  
>>  static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
>> @@ -427,8 +429,6 @@ static void virtio_net_reset(VirtIODevice *vdev)
>>      n->nobcast = 0;
>>      /* multiqueue is disabled by default */
>>      n->curr_queues = 1;
>> -    timer_del(n->announce_timer);
>> -    n->announce_counter = 0;
>>      n->status &= ~VIRTIO_NET_S_ANNOUNCE;
>>  
>>      /* Flush any MAC and VLAN filter table state */
>> @@ -868,11 +868,6 @@ static int virtio_net_handle_announce(VirtIONet *n, 
>> uint8_t cmd,
>>      if (cmd == VIRTIO_NET_CTRL_ANNOUNCE_ACK &&
>>          n->status & VIRTIO_NET_S_ANNOUNCE) {
>>          n->status &= ~VIRTIO_NET_S_ANNOUNCE;
>> -        if (n->announce_counter) {
>> -            timer_mod(n->announce_timer,
>> -                      qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
>> -                      self_announce_delay(n->announce_counter));
>> -        }
>>          return VIRTIO_NET_OK;
>>      } else {
>>          return VIRTIO_NET_ERR;
> 
> you will notice that this runs at VM speeds with QEMU_CLOCK_VIRTUAL,
> while the self announce you are tying this to runs with
> QEMU_CLOCK_REALTIME.
> 
> So this switch seems wrong to me: by the time VM is started
> on destination all timers might have expired.
> 

That explains what I am seeing now.  Hmm... may be combining them this way
isn't the right approach.  I think I'll leave RARPs alone and export an ability
to start the a nic provided announce feature.

Then Germano's qmp command would be able to call this one if available and the 
old
one if not.  That way, on user-triggered announcements, we wouldn't need to do 
the
RARPs, if a better announcement capability is present.

That way current behavior is preserved for migrations.

Thanks
-vlad

> 
>> @@ -1609,12 +1604,6 @@ static int virtio_net_post_load_device(void *opaque, 
>> int version_id)
>>          qemu_get_subqueue(n->nic, i)->link_down = link_down;
>>      }
>>  
>> -    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
>> -        virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
>> -        n->announce_counter = SELF_ANNOUNCE_ROUNDS;
>> -        timer_mod(n->announce_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL));
>> -    }
>> -
>>      return 0;
>>  }
>>  
>> @@ -1829,6 +1818,7 @@ static NetClientInfo net_virtio_info = {
>>      .receive = virtio_net_receive,
>>      .link_status_changed = virtio_net_set_link_status,
>>      .query_rx_filter = virtio_net_query_rxfilter,
>> +    .announce = virtio_net_announce,
>>  };
>>  
>>  static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
>> @@ -1934,8 +1924,6 @@ static void virtio_net_device_realize(DeviceState 
>> *dev, Error **errp)
>>      qemu_macaddr_default_if_unset(&n->nic_conf.macaddr);
>>      memcpy(&n->mac[0], &n->nic_conf.macaddr, sizeof(n->mac));
>>      n->status = VIRTIO_NET_S_LINK_UP;
>> -    n->announce_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
>> -                                     virtio_net_announce_timer, n);
>>  
>>      if (n->netclient_type) {
>>          /*
>> @@ -1997,8 +1985,6 @@ static void virtio_net_device_unrealize(DeviceState 
>> *dev, Error **errp)
>>          virtio_net_del_queue(n, i);
>>      }
>>  
>> -    timer_del(n->announce_timer);
>> -    timer_free(n->announce_timer);
>>      g_free(n->vqs);
>>      qemu_del_nic(n->nic);
>>      virtio_cleanup(vdev);
>> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
>> index 1eec9a2..0c597f4 100644
>> --- a/include/hw/virtio/virtio-net.h
>> +++ b/include/hw/virtio/virtio-net.h
>> @@ -94,8 +94,6 @@ typedef struct VirtIONet {
>>      char *netclient_name;
>>      char *netclient_type;
>>      uint64_t curr_guest_offloads;
>> -    QEMUTimer *announce_timer;
>> -    int announce_counter;
>>      bool needs_vnet_hdr_swap;
>>  } VirtIONet;
>>  
>> diff --git a/include/net/net.h b/include/net/net.h
>> index 99b28d5..598f523 100644
>> --- a/include/net/net.h
>> +++ b/include/net/net.h
>> @@ -64,6 +64,7 @@ typedef int (SetVnetLE)(NetClientState *, bool);
>>  typedef int (SetVnetBE)(NetClientState *, bool);
>>  typedef struct SocketReadState SocketReadState;
>>  typedef void (SocketReadStateFinalize)(SocketReadState *rs);
>> +typedef void (NetAnnounce)(NetClientState *);
>>  
>>  typedef struct NetClientInfo {
>>      NetClientDriver type;
>> @@ -84,6 +85,7 @@ typedef struct NetClientInfo {
>>      SetVnetHdrLen *set_vnet_hdr_len;
>>      SetVnetLE *set_vnet_le;
>>      SetVnetBE *set_vnet_be;
>> +    NetAnnounce *announce;
>>  } NetClientInfo;
>>  
>>  struct NetClientState {
>> diff --git a/migration/savevm.c b/migration/savevm.c
>> index 3b19a4a..5c1d8dc 100644
>> --- a/migration/savevm.c
>> +++ b/migration/savevm.c
>> @@ -113,9 +113,15 @@ static void qemu_announce_self_iter(NICState *nic, void 
>> *opaque)
>>      int len;
>>  
>>      trace_qemu_announce_self_iter(qemu_ether_ntoa(&nic->conf->macaddr));
>> +
>>      len = announce_self_create(buf, nic->conf->macaddr.a);
>>  
>>      qemu_send_packet_raw(qemu_get_queue(nic), buf, len);
>> +
>> +    /* if the NIC provides it's own announcement support, use it as well */
>> +    if (nic->ncs->info->announce) {
>> +        nic->ncs->info->announce(nic->ncs);
>> +    }
>>  }
> 
> 
> Can we switch existing qemu announcements to QEMU_CLOCK_VIRTUAL?
> 
> It's an interesting question, and I'm not sure.
> 
> I note that this seems to interact interestingly with recent dgilbert's
> patch sweaking announcement timing. Some coordination might be
> helpful here.
> 
> 
>>  
>> -- 
>> 2.7.4