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

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

 Hello!

> >  Wrong. I tried to unconditionally enforce it in qemu (my guest does support it), and the
> link stopped working at all. I don't understand why.
> 
> I'm wondering how did you do that? Why do you need enforece it in QEMU?
> Isn't it already supported so far?

 I mean - qemu first asks vhost-user server (ovs/DPDK in our case) about capabilities, then negotiates them with the guest. And DPDK
doesn't report VIRTIO_NET_F_GUEST_ANNOUNCE, so i just ORed this flag in qemu before the negotiation with guest (because indeed my
logic says that the host should not do anything special about it). So the overall effect is the same as in your patch

> diff --git a/lib/librte_vhost/virtio-net.c
> b/lib/librte_vhost/virtio-net.c
> index 03044f6..0ba5045 100644
> --- a/lib/librte_vhost/virtio-net.c
> +++ b/lib/librte_vhost/virtio-net.c
> @@ -74,6 +74,7 @@ static struct virtio_net_config_ll *ll_root;
>  #define VHOST_SUPPORTED_FEATURES ((1ULL << VIRTIO_NET_F_MRG_RXBUF) | \
>                                 (1ULL << VIRTIO_NET_F_CTRL_VQ) | \
>                                 (1ULL << VIRTIO_NET_F_CTRL_RX) | \
> +                               (1ULL << VIRTIO_NET_F_GUEST_ANNOUNCE) | \
>                                 (VHOST_SUPPORTS_MQ)            | \
>                                 (1ULL << VIRTIO_F_VERSION_1)   | \
>                                 (1ULL << VHOST_F_LOG_ALL)      | \

 But i was somehow wrong and this causes the whole thing to stop working instead. Even after just booting up the network doesn't
work and PINGs do not pass.

> However, I found the GARP is not sent out at all, due to an error
> I met and reported before:
> 
>     KVM: injection failed, MSI lost (Operation not permitted)

 Interesting, i don't have this problem here. Some bug in your kernel/hardware?

> One thing worth noting is that it happened only when I did live migration
> on two different hosts (the two hosts happened to be using a same old
> kernel: v3.11.10).  It works pretty well on same host. So, seems like
> a KVM bug then?

 3.18.9 here and no this problem.

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