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From: Jason Wang <jasowang@redhat.com>
To: David Miller <davem@davemloft.net>, willemdebruijn.kernel@gmail.com
Cc: mkubecek@suse.cz, netdev@vger.kernel.org,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Vlad Yasevic <vyasevic@redhat.com>
Subject: Re: regression: UFO removal breaks kvm live migration
Date: Wed, 8 Nov 2017 16:49:57 +0900	[thread overview]
Message-ID: <dc9af6e2-a886-3fc6-8f34-70d87a7a0d01@redhat.com> (raw)
In-Reply-To: <20171108.152624.282888162096095926.davem@davemloft.net>



On 2017年11月08日 15:26, David Miller wrote:
> From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> Date: Wed, 8 Nov 2017 12:36:26 +0900
>
>> On Tue, Nov 7, 2017 at 5:02 PM, Michal Kubecek <mkubecek@suse.cz> wrote:
>>> I didn't have time to think it through yet but perhaps we could allow
>>> setting TUN_F_UFO and ignore its value.
>> If the feature is enabled guests may try to send UFO packets, which
>> the host is no longer able to fragment.
>>
>> virtio_net_hdr_to_skb will drop the packets immediately based on
>> gso_type and tun_get_user will return EINVAL.
>>
>> Still, perhaps that's preferable as migration will succeed and most
>> guests won't ever try to send those packets in the first place.
> However, this would create the situation where there is no way
> to properly probe for the actual presence of UFO support.

I think we should not have any assumption on how guest will use the 
feature. So I could not come a better than bring it back partially for 
TAP, looks like we only need segment them in tun_get_user().

Thanks

  reply	other threads:[~2017-11-08  7:50 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-07  8:02 regression: UFO removal breaks kvm live migration Michal Kubecek
2017-11-08  3:36 ` Willem de Bruijn
2017-11-08  6:26   ` David Miller
2017-11-08  7:49     ` Jason Wang [this message]
2017-11-08  8:08       ` Willem de Bruijn
2017-11-08  8:25         ` Jason Wang
2017-11-08 11:32           ` David Miller
2017-11-08 12:53             ` Jason Wang
2017-11-08 12:58               ` David Miller
2017-11-10  5:32               ` Willem de Bruijn
2017-11-10  5:59                 ` David Miller
2017-11-17 14:31                 ` Willem de Bruijn
2017-11-17 14:48                   ` Willem de Bruijn
2017-11-17 23:00                     ` Willem de Bruijn
2017-11-08 16:01             ` Michael S. Tsirkin

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