Re: [PATCH 0/4 for 2.3] vhost-user live migration support

[Pavel Fedin <p.fedin@samsung.com>]

 Hello!

> No idea. Maybe you have changed some other configures (such as of ovs)
> without notice? Or, the ovs bridge interface resets?

 I don't touch the ovs at all. Just shut down the guest, rebuild the qemu, reinstall it, run the guest.

> 
> BTW, would you please try my v1 patch set with above diff applied to
> see if the ping loss is still there. You might also want to run tcpdump
> with the dest host ovs bridge, to see if GARP is actually sent.

 Retested with wireshark running on the host. I used my qemu patch instead, but it should not matter at all:
--- cut ---
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 1b6c5ac..5ca2987 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -480,7 +480,12 @@ static int vhost_user_get_u64(struct vhost_dev *dev, int request, uint64_t *u64)

 static int vhost_user_get_features(struct vhost_dev *dev, uint64_t *features)
 {
-    return vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
+    int ret = vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
+
+    if (!ret) {
+        virtio_add_feature(features, VIRTIO_NET_F_GUEST_ANNOUNCE);
+    }
+    return ret;
 }

 static int vhost_user_set_owner(struct vhost_dev *dev)
--- cut ---

 So, here are both wireshark captures on the host side:

1. Without the patch

root@nfv_test_x86_64 / # tshark -i ovs-br0
Running as user "root" and group "root". This could be dangerous.
Capturing on 'ovs-br0'
  1   0.000000           :: -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  2   0.003304 RealtekU_3b:83:1a -> Broadcast    ARP 42 Gratuitous ARP for 192.168.6.2 (Reply)
  3   0.669957           :: -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  4   0.858957           :: -> ff02::1:ff3b:831a ICMPv6 78 Neighbor Solicitation for fe80::5054:ff:fe3b:831a
  5   1.858968 fe80::5054:ff:fe3b:831a -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  6   2.300948 fe80::5054:ff:fe3b:831a -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  7   2.527088 fe80::5054:ff:fe3b:831a -> ff02::2      ICMPv6 62 Router Solicitation
  8   2.527800 RealtekU_3b:83:1a -> Broadcast    ARP 42 Gratuitous ARP for 192.168.6.2 (Request)
  9   6.526814 fe80::5054:ff:fe3b:831a -> ff02::2      ICMPv6 62 Router Solicitation
 10  10.526993 fe80::5054:ff:fe3b:831a -> ff02::2      ICMPv6 62 Router Solicitation
 11  15.984632 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 12  15.984643 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 13  15.984772  192.168.6.2 -> 192.168.6.1  ICMP 98 Echo (ping) request  id=0x0477, seq=1/256, ttl=64
 14  15.984798  192.168.6.1 -> 192.168.6.2  ICMP 98 Echo (ping) reply    id=0x0477, seq=1/256, ttl=64 (request in 13)
 15  16.984970  192.168.6.2 -> 192.168.6.1  ICMP 98 Echo (ping) request  id=0x0477, seq=2/512, ttl=64
 16  16.984991  192.168.6.1 -> 192.168.6.2  ICMP 98 Echo (ping) reply    id=0x0477, seq=2/512, ttl=64 (request in 15)
 17  17.984956  192.168.6.2 -> 192.168.6.1  ICMP 98 Echo (ping) request  id=0x0477, seq=3/768, ttl=64
 18  17.984975  192.168.6.1 -> 192.168.6.2  ICMP 98 Echo (ping) reply    id=0x0477, seq=3/768, ttl=64 (request in 17)
 19  20.994535 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 Who has 192.168.6.2?  Tell 192.168.6.1
 20  20.994637 RealtekU_3b:83:1a -> be:e1:71:c1:47:4d ARP 42 192.168.6.2 is at 52:54:00:3b:83:1a
^C20 packets captured

2. With the patch

root@nfv_test_x86_64 / # tshark -i ovs-br0
Running as user "root" and group "root". This could be dangerous.
Capturing on 'ovs-br0'
  1   0.000000           :: -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  2   0.000969 RealtekU_3b:83:1a -> Broadcast    ARP 42 Gratuitous ARP for 192.168.6.2 (Reply)
  3   0.156966           :: -> ff02::1:ff3b:831a ICMPv6 78 Neighbor Solicitation for fe80::5054:ff:fe3b:831a
  4   0.536948           :: -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  5   1.156968 fe80::5054:ff:fe3b:831a -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  6   1.312708 fe80::5054:ff:fe3b:831a -> ff02::2      ICMPv6 62 Router Solicitation
  7   1.629960 fe80::5054:ff:fe3b:831a -> ff02::16     ICMPv6 90 Multicast Listener Report Message v2
  8   2.314713 RealtekU_3b:83:1a -> Broadcast    ARP 42 Gratuitous ARP for 192.168.6.2 (Request)
  9   5.313333 fe80::5054:ff:fe3b:831a -> ff02::2      ICMPv6 62 Router Solicitation
 10   9.315486 fe80::5054:ff:fe3b:831a -> ff02::2      ICMPv6 62 Router Solicitation
 11  21.536450 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 12  21.536461 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 13  22.538937 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 14  22.538943 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 15  23.540937 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 16  23.540942 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 17  25.537519 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 18  25.537525 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 19  26.538939 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 20  26.538944 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 21  27.540937 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 22  27.540942 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 23  29.538475 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 24  29.538482 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 25  30.538935 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 26  30.538941 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
 27  31.540935 RealtekU_3b:83:1a -> Broadcast    ARP 42 Who has 192.168.6.1?  Tell 192.168.6.2
 28  31.540941 be:e1:71:c1:47:4d -> RealtekU_3b:83:1a ARP 42 192.168.6.1 is at be:e1:71:c1:47:4d
^C28 packets captured

 Obviously, the guest simply doesn't read incoming packets. ifconfig for the interface on guest side shows:

RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 9 overruns 0 frame 9

 BTW, number 9 exactly matches the number of ARP replies from the host. The question is - why? Looks like guest behavior changes
somehow. Is it a bug in guest? It's very strange, because in these sessions i see only one difference in IPv6 packets:

  4   0.858957           :: -> ff02::1:ff3b:831a ICMPv6 78 Neighbor Solicitation for fe80::5054:ff:fe3b:831a

This is present in session #1 and missing from session #2. Can it affect the whole thing somehow? But i don't even use IPv6.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia