netdev - [PATCH net v2 2/2] ixgbe: fix unexpected VLAN Rx in promisc mode on VF

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Message-Id: <20220406095252.22338-3-olivier.matz@6wind.com>
Date:   Wed,  6 Apr 2022 11:52:52 +0200
From:   Olivier Matz <olivier.matz@...nd.com>
To:     netdev@...r.kernel.org
Cc:     Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, intel-wired-lan@...osl.org,
        Paul Menzel <pmenzel@...gen.mpg.de>, stable@...r.kernel.org,
        Nicolas Dichtel <nicolas.dichtel@...nd.com>
Subject: [PATCH net v2 2/2] ixgbe: fix unexpected VLAN Rx in promisc mode on VF

When the promiscuous mode is enabled on a VF, the IXGBE_VMOLR_VPE
bit (VLAN Promiscuous Enable) is set. This means that the VF will
receive packets whose VLAN is not the same than the VLAN of the VF.

For instance, in this situation:

┌────────┐    ┌────────┐    ┌────────┐
│        │    │        │    │        │
│        │    │        │    │        │
│     VF0├────┤VF1  VF2├────┤VF3     │
│        │    │        │    │        │
└────────┘    └────────┘    └────────┘
   VM1           VM2           VM3

vf 0:  vlan 1000
vf 1:  vlan 1000
vf 2:  vlan 1001
vf 3:  vlan 1001

If we tcpdump on VF3, we see all the packets, even those transmitted
on vlan 1000.

This behavior prevents to bridge VF1 and VF2 in VM2, because it will
create a loop: packets transmitted on VF1 will be received by VF2 and
vice-versa, and bridged again through the software bridge.

This patch remove the activation of VLAN Promiscuous when a VF enables
the promiscuous mode. However, the IXGBE_VMOLR_UPE bit (Unicast
Promiscuous) is kept, so that a VF receives all packets that has the
same VLAN, whatever the destination MAC address.

Fixes: 8443c1a4b192 ("ixgbe, ixgbevf: Add new mbox API xcast mode")
Cc: stable@...r.kernel.org
Cc: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Signed-off-by: Olivier Matz <olivier.matz@...nd.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
index 8d108a78941b..d4e63f0644c3 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
@@ -1208,9 +1208,9 @@ static int ixgbe_update_vf_xcast_mode(struct ixgbe_adapter *adapter,
 			return -EPERM;
 		}
 
-		disable = 0;
+		disable = IXGBE_VMOLR_VPE;
 		enable = IXGBE_VMOLR_BAM | IXGBE_VMOLR_ROMPE |
-			 IXGBE_VMOLR_MPE | IXGBE_VMOLR_UPE | IXGBE_VMOLR_VPE;
+			 IXGBE_VMOLR_MPE | IXGBE_VMOLR_UPE;
 		break;
 	default:
 		return -EOPNOTSUPP;
-- 
2.30.2