On 06/09/2016 13:57, Paul Durrant wrote: >> -----Original Message----- >> From: Anthony Wright [mailto:anth...@overnetdata.com] >> Sent: 06 September 2016 13:23 >> To: Xen-devel <xen-devel@lists.xen.org> >> Cc: Paul Durrant <paul.durr...@citrix.com> >> Subject: Bug in hash changes to netback in 4.7.2 kernel >> >> When I run Xen (4.7.0) nested in VirtualBox (5.0.24_Ubuntu r108355) with a >> linux-4.7.2 Dom0 kernel, none of my DomU's (linux-3.17.3) have network >> connectivity because they reject all packets with the error 'Invalid extra >> type: >> 4'. When I run exactly the same setup on bare metal, I don't get the error >> messages. >> >> From poking around in the code this seems to be because the 4.7.2 kernel >> wrongly decides that the DomU's will understand EXTRA_TYPE_HASH, and so >> attach it to the network packet. Since the DomU's don't understand the extra >> info their netfront driver rejects the whole packet. > The code in xenvif_select_queue() deliberately clears the skb->sw_hash field > (which gates adding the new extra type) if the hash algorithm selected by the > frontend is 'none', which should be the default. So, unless you have a > frontend that is implementing the control ring protocol, but failing to > recognize the new extra type I'm not how you're seeing the problem... unless > somehow a packet which hash is getting into netback's start_xmit without > first having gone through select_queue? I very much doubt that the frontend is implementing the control ring protocol, the DomUs are running stock linux-3.17.3. I build the system from source, so happy to re-compile with debug code.
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