iavf: fix wrong VLAN mask for legacy Rx descriptors L2TAG2

The IAVF_RXD_LEGACY_L2TAG2_M mask was incorrectly defined as
GENMASK_ULL(63, 32), extracting 32 bits from qw2 instead of the
16-bit VLAN tag. In the legacy Rx descriptor layout, the 2nd L2TAG2
(VLAN tag) occupies bits 63:48 of qw2, not 63:32.

The oversized mask causes FIELD_GET to return a 32-bit value where the
actual VLAN tag sits in bits 31:16. When this value is passed to
iavf_receive_skb() as a u16 parameter, it gets truncated to the lower
16 bits (which contain the 1st L2TAG2, typically zero). As a result,
__vlan_hwaccel_put_tag() is never called and software VLAN interfaces
on VFs receive no traffic.

This affects VFs behind ice PF (VIRTCHNL VLAN v2) when the PF
advertises VLAN stripping into L2TAG2_2 and legacy descriptors are
used.

The flex descriptor path already uses the correct mask
(IAVF_RXD_FLEX_L2TAG2_2_M = GENMASK_ULL(63, 48)).

Reproducer:
 1. Create 2 VFs on ice PF (echo 2 > sriov_numvfs)
 2. Disable spoofchk on both VFs
 3. Move each VF into a separate network namespace
 4. On each VF: create VLAN interface (e.g. vlan 198), assign IP,
    bring up
 5. Set rx-vlan-offload OFF on both VFs
 6. Ping between VLAN interfaces -> expect PASS
    (VLAN tag stays in packet data, kernel matches in-band)
 7. Set rx-vlan-offload ON on both VFs
 8. Ping between VLAN interfaces -> expect FAIL if bug present
    (HW strips VLAN tag into descriptor L2TAG2 field, wrong mask
    extracts bits 47:32 instead of 63:48, truncated to u16 -> zero,
    __vlan_hwaccel_put_tag() never called, packet delivered to parent
    interface, not VLAN interface)

The reproducer requires legacy Rx descriptors. On modern ice + iavf
with full PTP support, flex descriptors are always negotiated and the
buggy legacy path is never reached. Flex descriptors require all of:
 - CONFIG_PTP_1588_CLOCK enabled
 - VIRTCHNL_VF_OFFLOAD_RX_FLEX_DESC granted by PF
 - PTP capabilities negotiated (VIRTCHNL_VF_CAP_PTP)
 - VIRTCHNL_1588_PTP_CAP_RX_TSTAMP supported
 - VIRTCHNL_RXDID_2_FLEX_SQ_NIC present in DDP profile

If any condition is not met, iavf_select_rx_desc_format() falls back
to legacy descriptors (RXDID=1) and the wrong L2TAG2 mask is hit.

Fixes: 2dc8e7c36d80 ("iavf: refactor iavf_clean_rx_irq to support legacy and flex descriptors")
Signed-off-by: Petr Oros <poros@redhat.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260416-iwl-net-submission-2026-04-14-v2-10-686c33c9828d@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions