Messages in this thread |  | | Date | Thu, 13 Feb 2014 07:15:59 +0200 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH net] virtio-net: alloc big buffers also when guest can receive UFO |
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On Thu, Feb 13, 2014 at 11:02:13AM +0800, Jason Wang wrote: > On 02/12/2014 07:59 PM, Michael S. Tsirkin wrote: > > On Wed, Feb 12, 2014 at 01:43:28PM +0800, Jason Wang wrote: > >> > We should alloc big buffers also when guest can receive UFO > >> > pakcets. Otherwise the big packets will be truncated when mergeable rx > >> > buffer is disabled. > > Not truncated, they will be dropped. > > > > Why dropped? We enable the ufo on tap0 if VIRTIO_NET_F_GUEST_UFO is > negotiated. So skb was queued on the receive queue. But since the > receive buffer is small, it will be truncated during tun_put_user().
Hypervisor shouldn't truncate packets silently - if it does it's a hypervisor bug. Passing malformed packets to guest is a bad idea.
-- MST
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