On Tue, Aug 4, 2015 at 7:50 PM, Marc-André Lureau
<marcandre.lur...@gmail.com> wrote:
> Hi Thibaut
>
> On Mon, Aug 3, 2015 at 11:22 AM, Thibaut Collet
> <thibaut.col...@6wind.com> wrote:
>> Some vhost user backends are able to support live migration.
>> To provide this service the following features must be added:
>> 1. Add the VIRTIO_NET_F_GUEST_ANNOUNCE capability to vhost-net when netdev
>> backend is vhost-user.
>> 2. Provide a nop receive callback to vhost-user.
>> This callback is used only by qemu_announce_self after a migration to send
>> fake RARP to avoid network outage for peers talking to the migrated guest.
>> - For guest with GUEST_ANNOUNCE capabilities these packets must be
>> discarded,
>> GARP are sent by the guest thanks the GUEST_ANNOUNCE.
>> - For guest without GUEST_ANNOUNCE capabilities these packets are
>> discarded
>> too, migration termination is notified when the guest sends packets.
>>
>> Signed-off-by: Thibaut Collet <thibaut.col...@6wind.com>
>> ---
>> hw/net/vhost_net.c | 2 ++
>> net/vhost-user.c | 25 +++++++++++++++++++++++--
>> 2 files changed, 25 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
>> index c864237..9850520 100644
>> --- a/hw/net/vhost_net.c
>> +++ b/hw/net/vhost_net.c
>> @@ -85,6 +85,8 @@ static const int user_feature_bits[] = {
>> VIRTIO_NET_F_CTRL_MAC_ADDR,
>> VIRTIO_NET_F_CTRL_GUEST_OFFLOADS,
>>
>> + VIRTIO_NET_F_GUEST_ANNOUNCE,
>> +
>> VIRTIO_NET_F_MQ,
>>
>> VHOST_INVALID_FEATURE_BIT
>> diff --git a/net/vhost-user.c b/net/vhost-user.c
>> index 93dcecd..2290271 100644
>> --- a/net/vhost-user.c
>> +++ b/net/vhost-user.c
>> @@ -65,6 +65,28 @@ static void vhost_user_stop(VhostUserState *s)
>> s->vhost_net = 0;
>> }
>>
>> +static ssize_t vhost_user_receive(NetClientState *nc, const uint8_t *buf,
>> + size_t size)
>> +{
>> + /* A live migration is done. Display an error if the packet is not a
>> RARP.
>> + * RARP are just discarded: guest is already notified about live
>> migration
>> + * by the virtio-net NIC or by the vhost-user backend.
>> + */
>> + if (size != 60) {
>> + static int display_trace = 1;
>> +
>> + if (display_trace) {
>> + fprintf(stderr,
>> + "Vhost user expects only RARP (size 60)."
>> + "Receives unexpected packets with size %lu\n",
>> + size);
>> + fflush(stderr);
>> + display_trace = 0;
>> + }
>> + }
>> + return size;
>> +}
>
> This warning appears during a dummy boot with vapp: qemu-system-x86_64
> -m 512 -object
> memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs/,share=on
> -numa node,memdev=mem -netdev
> vhost-user,id=net0,chardev=chr0,vhostforce -device
> virtio-net-pci,netdev=net0 -chardev
> socket,id=chr0,path=/tmp/vapp.sock.
>
> I think silentely returning 0 (without warning) is the right way to
> keep the packets queued in the ring instead. But I must say I am quite
> confused as this is triggered by a VIRTIO_PCI_QUEUE_NOTIFY ioport
> write, and I fail to see how vhost-user handles it then without
> eventfd kick...
>
>> static void vhost_user_cleanup(NetClientState *nc)
>> {
>> VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
>> @@ -90,6 +112,7 @@ static bool vhost_user_has_ufo(NetClientState *nc)
>> static NetClientInfo net_vhost_user_info = {
>> .type = NET_CLIENT_OPTIONS_KIND_VHOST_USER,
>> .size = sizeof(VhostUserState),
>> + .receive = vhost_user_receive,
>> .cleanup = vhost_user_cleanup,
>> .has_vnet_hdr = vhost_user_has_vnet_hdr,
>> .has_ufo = vhost_user_has_ufo,
>> @@ -143,8 +166,6 @@ static int net_vhost_user_init(NetClientState *peer,
>> const char *device,
>>
>> s = DO_UPCAST(VhostUserState, nc, nc);
>>
>> - /* We don't provide a receive callback */
>> - s->nc.receive_disabled = 1;
>> s->chr = chr;
>>
>> qemu_chr_add_handlers(s->chr, NULL, NULL, net_vhost_user_event, s);
>> --
>> 1.7.10.4
>>
>
>
>
> --
> Marc-André Lureau
Hi,
I have reproduced the issue and the message receive by vhost-user is
quite strange: this message is a virtio header plus a bootp/dhcp
request (I do not understand why there are the virtio header)
With a dummy boot, vhost user backend already receives 4 bootp/dhcp
requests form the bios guest so I do not see any interest to transmit
this request to vhostuser backend.
I suggest to remove the warning and discard the dhcp/bootp request (it
is useless to duplicate bootp/dhcp request)
Thibaut.
