[dpdk-users] How to use .last and .spec fields in the Generic Flow API?

[Raslan Darawsheh]

Hi Andrew,

I tried to explain it in general for last and mask.
But, for MLX4 in general it can have support only for 0xffff mask or 0x0 mask which mean that you can only do it for one port or any.
This also applies for IPv4 and TCP items.

So for the range you need to explicitly add a separate rule for each port that you want.

Kindest regards,
Raslan Darawsheh

> -----Original Message-----
> From: Andrew Bainbridge <andbain at microsoft.com>
> Sent: Thursday, March 7, 2019 1:10 PM
> To: Raslan Darawsheh <rasland at mellanox.com>; users <users at dpdk.org>
> Subject: RE: [dpdk-users] How to use .last and .spec fields in the Generic
> Flow API?
> 
> Hi Raslan
> 
> Thanks for the reply. It sounds very sensible. Unfortunately I can't get it to
> work.
> 
> If I do not set the mask, I get the "range between spec and last is larger than
> mask" error again.
> 
> If I set the mask to 0, then all udp dst port numbers are accepted.
> 
> If I set the mask to 0xff, I get, "mlx4 does not support matching partial UDP
> fields".
> 
> Do any of these work on the PMD you use? The generic flow docs
> (https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdo
> c.dpdk.org%2Fguides%2Fprog_guide%2Frte_flow.html&data=02%7C01
> %7Crasland%40mellanox.com%7Cb79d945b1a8d4597044f08d6a2ed8282%7Ca
> 652971c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636875538317844006&am
> p;sdata=Jk3US8esY0vlWXyWyDqyjWlYG4DzpQFERN7L864Xdo0%3D&res
> erved=0 section 9.2.3) say, "mask is a simple bit-mask applied before
> interpreting the contents of spec and last", which sort-of implies I need to
> set the mask to non-zero even when using "last".
> 
> I can't find any other relevant documentation or example code.
> 
> Thanks,
> Andrew
> 
> -----Original Message-----
> From: Raslan Darawsheh <rasland at mellanox.com>
> Sent: 07 March 2019 08:52
> To: Andrew Bainbridge <andbain at microsoft.com>; users <users at dpdk.org>
> Subject: RE: [dpdk-users] How to use .last and .spec fields in the Generic
> Flow API?
> 
> Hi Andrew,
> 
> You are specifying a mask and the last for the item.
> Based on the mask that you specified it means that match only the
> udp_dst_port that was specified since the mask is 0xffff Which is causing
> conflicts with the range.
> Try it without setting the mask or set the mask to be 0x0
> 
> Kindest regards,
> Raslan Darawsheh
> 
> > -----Original Message-----
> > From: users <users-bounces at dpdk.org> On Behalf Of Andrew Bainbridge
> > Sent: Wednesday, March 6, 2019 5:30 PM
> > To: users <users at dpdk.org>
> > Subject: [dpdk-users] How to use .last and .spec fields in the Generic
> > Flow API?
> >
> > Hi
> >
> > How should I specify a range of UDP ports in the generic flow API?
> > Here's what I've tried...
> >
> > I'm trying to create a flow to move packets with UDP dest ports from
> > 1234 to
> > 1244 into a specified queue. It works fine if I specify a single port
> > of 1234, instead of the range. Here's how I set the flow item for that:
> >
> >     struct rte_flow_item_udp udp_spec = { 0 };
> >     struct rte_flow_item_udp udp_mask = { 0 };
> >     udp_spec.hdr.dst_port = htons(udp_dst_port);
> >     udp_mask.hdr.dst_port = 0xffff;
> >     pattern[2].type = RTE_FLOW_ITEM_TYPE_UDP;
> >     pattern[2].spec = &udp_spec;
> >     pattern[2].mask = &udp_mask;
> >
> > But if I attempt to specify the range, I believe I have to use the .last field.
> > When I do that, I get this error, 'range between "spec" and "last" is
> > larger than "mask"'. Here's how I set that flow item:
> >
> >     struct rte_flow_item_udp udp_spec = { 0 };
> >     struct rte_flow_item_udp udp_last = { 0 };
> >     struct rte_flow_item_udp udp_mask = { 0 };
> >     udp_spec.hdr.dst_port = htons(1234);
> >     udp_last.hdr.dst_port = htons(1244);
> >     udp_mask.hdr.dst_port = 0xffff;
> >     pattern[2].type = RTE_FLOW_ITEM_TYPE_UDP;
> >     pattern[2].spec = &udp_spec;
> >     pattern[2].last = &udp_last;
> >     pattern[2].mask = &udp_mask;
> >
> > I don't understand the error message. The range between spec and last is
> 10.
> > The mask is 0xffff. The error message seems wrong. But probably I just
> > misunderstood something.
> >
> > More details:
> >
> > I'm using the mlx4 PMD. The source of the error message is in
> > mlx4_flow_item_check(), where the code appears goes through each byte
> > of the spec and last and checks that:
> >
> >     (((const uint8_t *)item->spec)[i] & mask[i]) != (((const uint8_t
> > *)item-
> > >last)[i] & mask[i]))
> >
> > Which makes no sense to me. That appears to require that spec and last
> > are equal wherever mask is not zero.
> >
> > Any ideas?
> >
> > Thanks,
> > Andy