Re:Re: [PATCH v1 2/3] examples/l3fwd: relax the Offload requirement

[taozj888 <taozj888@163.com>]

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Hi Konstantin:
For your comments, please see my answer inline.
Thanks.




Trevor Tao

At 2023-10-09 17:03:11, "Konstantin Ananyev" <konstantin.v.ananyev@yandex.ru> wrote:
>02.10.2023 09:53, Trevor Tao пишет:
>> Now the port Rx offload mode is set to RTE_ETH_RX_OFFLOAD_CHECKSUM
>> by default, but some hw and/or virtual interface does not support
>> the offload mode presupposed, e.g., some virtio interfaces in
>> the cloud may only partly support RTE_ETH_RX_OFFLOAD_UDP_CKSUM/
>> RTE_ETH_RX_OFFLOAD_TCP_CKSUM,
>> but not RTE_ETH_RX_OFFLOAD_IPV4_CKSUM, and the error msg here:
>> 
>> Ethdev port_id=0 requested Rx offloads 0xe does not match Rx offloads
>> capabilities 0x201d in rte_eth_dev_configure()
>> 
>> So to enable the l3fwd running in that environment, the Rx mode requirement
>> can be relaxed to reflect the hardware feature reality here, and the l3fwd
>> can run smoothly then.
>> A warning msg would be provided to user in case it happens here.
>> 
>> On the other side, enabling the software cksum check in case missing the
>> hw support.
>> 
>> The relax action for rx cksum offload is just enabled when relax_rx_mode is
>> true which is false by default.
>> 
>> Signed-off-by: Trevor Tao <taozj888@163.com>
>> ---
>>   examples/l3fwd/l3fwd.h     | 12 ++++++++++--
>>   examples/l3fwd/l3fwd_em.h  |  2 +-
>>   examples/l3fwd/l3fwd_lpm.h |  2 +-
>>   examples/l3fwd/main.c      | 14 ++++++++++++++
>>   4 files changed, 26 insertions(+), 4 deletions(-)
>> 
>> diff --git a/examples/l3fwd/l3fwd.h b/examples/l3fwd/l3fwd.h
>> index b55855c932..fd98ad3373 100644
>> --- a/examples/l3fwd/l3fwd.h
>> +++ b/examples/l3fwd/l3fwd.h
>> @@ -159,7 +159,7 @@ send_single_packet(struct lcore_conf *qconf,
>>   
>>   #ifdef DO_RFC_1812_CHECKS
>>   static inline int
>> -is_valid_ipv4_pkt(struct rte_ipv4_hdr *pkt, uint32_t link_len)
>> +is_valid_ipv4_pkt(struct rte_ipv4_hdr *pkt, uint32_t link_len, uint64_t ol_flags)
>>   {
>>   	/* From http://www.rfc-editor.org/rfc/rfc1812.txt section 5.2.2 */
>>   	/*
>> @@ -170,7 +170,15 @@ is_valid_ipv4_pkt(struct rte_ipv4_hdr *pkt, uint32_t link_len)
>>   		return -1;
>>   
>>   	/* 2. The IP checksum must be correct. */
>> -	/* this is checked in H/W */
>> +	/* if this is not checked in H/W, check it. */
>> +	if ((ol_flags & RTE_ETH_RX_OFFLOAD_IPV4_CKSUM) == 0) {
>> +		uint16_t actual_cksum, expected_cksum;
>> +		actual_cksum = pkt->hdr_checksum;
>> +		pkt->hdr_checksum = 0;
>> +		expected_cksum = rte_ipv4_cksum(pkt);
>> +		if (actual_cksum != expected_cksum)
>> +			return -2;
>> +	}
>>   
>>   	/*
>>   	 * 3. The IP version number must be 4. If the version number is not 4
>> diff --git a/examples/l3fwd/l3fwd_em.h b/examples/l3fwd/l3fwd_em.h
>> index 7d051fc076..1fee2e2e6c 100644
>> --- a/examples/l3fwd/l3fwd_em.h
>> +++ b/examples/l3fwd/l3fwd_em.h
>> @@ -20,7 +20,7 @@ l3fwd_em_handle_ipv4(struct rte_mbuf *m, uint16_t portid,
>>   
>>   #ifdef DO_RFC_1812_CHECKS
>>   	/* Check to make sure the packet is valid (RFC1812) */
>> -	if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len) < 0) {
>> +	if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len, m->ol_flags) < 0) {
>>   		rte_pktmbuf_free(m);
>>   		return BAD_PORT;
>>   	}
>> diff --git a/examples/l3fwd/l3fwd_lpm.h b/examples/l3fwd/l3fwd_lpm.h
>> index c61b969584..5ddae7da0f 100644
>> --- a/examples/l3fwd/l3fwd_lpm.h
>> +++ b/examples/l3fwd/l3fwd_lpm.h
>> @@ -22,7 +22,7 @@ l3fwd_lpm_simple_forward(struct rte_mbuf *m, uint16_t portid,
>>   
>>   #ifdef DO_RFC_1812_CHECKS
>>   		/* Check to make sure the packet is valid (RFC1812) */
>> -		if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len) < 0) {
>> +		if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len) < 0, m->ol_flags) {
>

>Typo, pls fix.


>OK, I will fix it. Thanks.
>
>>   			rte_pktmbuf_free(m);
>>   			return;
>>   		}
>> diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
>> index 2c8f528d00..a48ae7f62b 100644
>> --- a/examples/l3fwd/main.c
>> +++ b/examples/l3fwd/main.c
>> @@ -1284,6 +1284,20 @@ l3fwd_poll_resource_setup(void)
>>   				local_port_conf.rx_adv_conf.rss_conf.rss_hf);
>>   		}
>>   
>> +		/* relax the rx offload requirement */
>> +		if ((local_port_conf.rxmode.offloads & dev_info.rx_offload_capa) !=
>> +			local_port_conf.rxmode.offloads) {
>
>
>Ok, but we relax only IP cksum.
>Though l3fwd tries to enable IP/TCP/UDP cksum.

>What if TCP/UDP is not supported, should we allow it or fail?


>I think the l3fwd just check the packet at the IP layer, and the TCP/UDP should not bother us here, so I think it can be allowed to relax them if they are not supported. 
What do think about it?
Thanks.




>
>
>> +			printf("Port %u requested Rx offloads 0x%"PRIx64" does not"
>> +				" match Rx offloads capabilities 0x%"PRIx64"\n",
>> +				portid, local_port_conf.rxmode.offloads,
>> +				dev_info.rx_offload_capa);
>> +			if (relax_rx_mode) {
>> +				local_port_conf.rxmode.offloads &= dev_info.rx_offload_capa;
>> +				printf("warning: modified the rx offload to 0x%"PRIx64" based on device"
>> +				" capability\n", local_port_conf.rxmode.offloads);
>> +			}
>> +		}
>> +
>>   		ret = rte_eth_dev_configure(portid, nb_rx_queue,
>>   					(uint16_t)n_tx_queue, &local_port_conf);
>>   		if (ret < 0)
>
>if you going to submit new version, pls don't forget to bump the version 

>number of the patch.


>OK, I will check it.
Thanks.

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