[ovs-dev] [PATCH v3] netdev-dpdk: add support for the RTE_ETH_EVENT_INTR_RESET event

Ilya Maximets i.maximets at samsung.com
Thu Sep 12 10:19:47 UTC 2019


On 12.09.2019 13:07, Eelco Chaudron wrote:
> 
> 
> On 12 Sep 2019, at 10:39, Ilya Maximets wrote:
> 
>> On 11.09.2019 16:20, Eelco Chaudron wrote:
>>> Currently, OVS does not register and therefore not handle the
>>> interface reset event from the DPDK framework. This would cause a
>>> problem in cases where a VF is used as an interface, and its
>>> configuration changes.
>>>
>>> As an example in the following scenario the MAC change is not
>>> detected/acted upon until OVS is restarted without the patch applied:
>>>
>>>   $ echo 1 > /sys/bus/pci/devices/0000:05:00.1/sriov_numvfs
>>>   $ ovs-vsctl add-port ovs_pvp_br0 dpdk0 -- \
>>>             set Interface dpdk0 type=dpdk -- \
>>>             set Interface dpdk0 options:dpdk-devargs=0000:05:0a.0
>>>
>>>   $ ip link set p5p2 vf 0 mac 52:54:00:92:d3:33
>>>
>>> Signed-off-by: Eelco Chaudron <echaudro at redhat.com>
>>> ---
>>
>> <snip>
>>
>>> @@ -4180,13 +4223,19 @@ netdev_dpdk_reconfigure(struct netdev *netdev)
>>>          && dev->rxq_size == dev->requested_rxq_size
>>>          && dev->txq_size == dev->requested_txq_size
>>>          && dev->socket_id == dev->requested_socket_id
>>> -        && dev->started) {
>>> +        && dev->started && !dev->reset_needed) {
>>>          /* Reconfiguration is unnecessary */
>>>
>>>          goto out;
>>>      }
>>>
>>> -    rte_eth_dev_stop(dev->port_id);
>>> +    if (dev->reset_needed) {
>>> +        rte_eth_dev_reset(dev->port_id);
>>
>> Thinking more about the change and looking at flow control configuration,
>> it seems that on reset we'll lost configurations done in set_config().
>> Device reset should return it to initial state, i.e. all the default settings,
>> but set_config() will not be called after that.
>> I know, that VFs commonly doesn't support flow control, but if we'll add like
>> real configuration of MAC address, it will be lost too.
>>
>> What do you think?
> 
> Doesn’t the full bridge run sequence take care of this?
> 
> So in callback we do netdev_request_reconfigure() which triggers the following sequence…
> 
> bridge_run__()
>  ...
>    dpif_netdev_run()
>      ...
>        reconfigure_datapath()
>          ...
>            netdev_dpdk_reconfigure()
> 
> But than also it will call in the next run
> 
> bridge_run()
>  ...
>    bridge_delete_or_reconfigure_ports()
>      ...
>         netdev_set_config()
>           netdev_dpdk_set_config()
> 
> 
> Or do I miss something?

dpif_netdev_run() is called from ofproto_type_run() which is called
unconditionally from the bridge_run().
But bridge_delete_or_reconfigure_ports() only called from bridge_reconfigure(),
which is protected by the following condition:

    if (ovsdb_idl_get_seqno(idl) != idl_seqno ||
        if_notifier_changed(ifnotifier)) {

i.e. if there will be no DB updates or there will be no netlink notifications,
set_config() will not be called. I understand that in your scenario there
might be netlink notification for interface changes since PF is controlled
by the kernel, but it might be not the case if PF attached as a DPDK port
to OVS or some other application.

> 
>>
>> BTW, there is a discussion about flow control configuration:
>> https://patchwork.ozlabs.org/patch/1159689/
>>
>>> +        dev->reset_needed = false;
>>> +    } else {
>>> +        rte_eth_dev_stop(dev->port_id);
>>> +    }
>>> +
>>>      dev->started = false;
>>>
>>>      err = netdev_dpdk_mempool_configure(dev);
> 
> 


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