Re: [dpdk-dev] [PATCH] vhost: disable host TSO for linear buffers without extbuf

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 10/17/19 5:00 PM, Ilya Maximets wrote:
> If linear buffers requested and external buffers are not, vhost
> will not be able to receive any buffer that doesn't fit in a
> single mbuf.  Moreover, if such a buffer will appear in a vring
> it will never be dequeued and the whole vring will become dead
> breaking the network connection.
> 
> Disable segmentation offloading from the host side to avoid
> having such a big buffers.
> 
> Cc: Flavio Leitner <fbl@sysclose.org>
> 
> Fixes: 5005bcda7123 ("vhost: add support for large buffers")
> Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
> ---
> 
> There is still an assumption that users are sane enough to have
> MTU sized mbufs in a memory pool and that guest will not change
> MTU to higher values.
> 
> We, probably, still need to have a check on dequeue path and
> drop oversized buffers in case of linear buffers to avoid stuck
> of the virtqueue.  Or simply drop support of '+linear -extbuf'
> case.
> 
> Note: Only compile tested due to lack of HW.
> 
>  lib/librte_vhost/socket.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 


Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime