netdev - Re: [PATCH net] i40e: report VF tx_dropped with tx_errors instead of tx

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <c9ecef85-a460-4442-95f5-99f0d3ff5496@intel.com>
Date: Thu, 17 Jul 2025 13:05:37 -0700
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: Dennis Chen <dechen@...hat.com>, <netdev@...r.kernel.org>
CC: <przemyslaw.kitszel@...el.com>, <andrew+netdev@...n.ch>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <intel-wired-lan@...ts.osuosl.org>
Subject: Re: [PATCH net] i40e: report VF tx_dropped with tx_errors instead of
 tx_discards



On 7/17/2025 9:46 AM, Dennis Chen wrote:
> On Wed, Jun 18, 2025 at 3:52 PM Dennis Chen <dechen@...hat.com> wrote:
>>
>> Currently the tx_dropped field in VF stats is not updated correctly
>> when reading stats from the PF. This is because it reads from
>> i40e_eth_stats.tx_discards which seems to be unused for per VSI stats,
>> as it is not updated by i40e_update_eth_stats() and the corresponding
>> register, GLV_TDPC, is not implemented[1].
>>
>> Use i40e_eth_stats.tx_errors instead, which is actually updated by
>> i40e_update_eth_stats() by reading from GLV_TEPC.
>>
>> To test, create a VF and try to send bad packets through it:
>>
>> $ echo 1 > /sys/class/net/enp2s0f0/device/sriov_numvfs
>> $ cat test.py
>> from scapy.all import *
>>
>> vlan_pkt = Ether(dst="ff:ff:ff:ff:ff:ff") / Dot1Q(vlan=999) / IP(dst="192.168.0.1") / ICMP()
>> ttl_pkt = IP(dst="8.8.8.8", ttl=0) / ICMP()
>>
>> print("Send packet with bad VLAN tag")
>> sendp(vlan_pkt, iface="enp2s0f0v0")
>> print("Send packet with TTL=0")
>> sendp(ttl_pkt, iface="enp2s0f0v0")
>> $ ip -s link show dev enp2s0f0
>> 16: enp2s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
>>      link/ether 3c:ec:ef:b7:e0:ac brd ff:ff:ff:ff:ff:ff
>>      RX:  bytes packets errors dropped  missed   mcast
>>               0       0      0       0       0       0
>>      TX:  bytes packets errors dropped carrier collsns
>>               0       0      0       0       0       0
>>      vf 0     link/ether e2:c6:fd:c1:1e:92 brd ff:ff:ff:ff:ff:ff, spoof checking on, link-state auto, trust off
>>      RX: bytes  packets  mcast   bcast   dropped
>>               0        0       0       0        0
>>      TX: bytes  packets   dropped
>>               0        0        0
>> $ python test.py
>> Send packet with bad VLAN tag
>> .
>> Sent 1 packets.
>> Send packet with TTL=0
>> .
>> Sent 1 packets.
>> $ ip -s link show dev enp2s0f0
>> 16: enp2s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
>>      link/ether 3c:ec:ef:b7:e0:ac brd ff:ff:ff:ff:ff:ff
>>      RX:  bytes packets errors dropped  missed   mcast
>>               0       0      0       0       0       0
>>      TX:  bytes packets errors dropped carrier collsns
>>               0       0      0       0       0       0
>>      vf 0     link/ether e2:c6:fd:c1:1e:92 brd ff:ff:ff:ff:ff:ff, spoof checking on, link-state auto, trust off
>>      RX: bytes  packets  mcast   bcast   dropped
>>               0        0       0       0        0
>>      TX: bytes  packets   dropped
>>               0        0        0
>>
>> A packet with non-existent VLAN tag and a packet with TTL = 0 are sent,
>> but tx_dropped is not incremented.
>>
>> After patch:
>>
>> $ ip -s link show dev enp2s0f0
>> 19: enp2s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
>>      link/ether 3c:ec:ef:b7:e0:ac brd ff:ff:ff:ff:ff:ff
>>      RX:  bytes packets errors dropped  missed   mcast
>>               0       0      0       0       0       0
>>      TX:  bytes packets errors dropped carrier collsns
>>               0       0      0       0       0       0
>>      vf 0     link/ether 4a:b7:3d:37:f7:56 brd ff:ff:ff:ff:ff:ff, spoof checking on, link-state auto, trust off
>>      RX: bytes  packets  mcast   bcast   dropped
>>               0        0       0       0        0
>>      TX: bytes  packets   dropped
>>               0        0        2
>>
>> Fixes: dc645daef9af5bcbd9c ("i40e: implement VF stats NDO")
>> Signed-off-by: Dennis Chen <dechen@...hat.com>
>>      Link: https://www.intel.com/content/www/us/en/content-details/596333/intel-ethernet-controller-x710-tm4-at2-carlsville-datasheet.html
>> ---
>>   drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> index 88e6bef69342..2dbe38eb9494 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> @@ -5006,7 +5006,7 @@ int i40e_get_vf_stats(struct net_device *netdev, int vf_id,
>>          vf_stats->broadcast  = stats->rx_broadcast;
>>          vf_stats->multicast  = stats->rx_multicast;
>>          vf_stats->rx_dropped = stats->rx_discards + stats->rx_discards_other;
>> -       vf_stats->tx_dropped = stats->tx_discards;
>> +       vf_stats->tx_dropped = stats->tx_errors;
>>
>>          return 0;
>>   }
>> --
>> 2.49.0
>>
> Hello,
> 
> Any update here?

Hi Dennis,

Let me check with our validation team and get their status on this.

Thanks,
Tony