gve: DQO: accept TSO packets with non-protocol gso_type bits

Since commit 014c607f86ab ("gve: add support for UDP GSO for DQO
format"), gve_prep_tso() matches shinfo->gso_type exactly. gso_type is
a bitmask, though: SKB_GSO_DODGY is set on every GSO packet that comes
from tun/tap, packet sockets or other untrusted sources, and
SKB_GSO_TCP_ECN and SKB_GSO_TCP_FIXEDID can be set as well. Such packets
hit the default case, gve_tx_add_skb_dqo() fails and gve_try_tx_skb()
drops them, counting them in tx_dropped.

These packets do reach the driver: tcp_gso_segment() passes DODGY skbs
through unsegmented to devices that support TSO, after recomputing
gso_segs, so drivers must tolerate the bit.

This breaks virtual machines behind a tap on GCE instances using the DQO
queue formats. Every TSO packet forwarded from a guest (gso_type
SKB_GSO_TCPV4 | SKB_GSO_DODGY) is dropped, and guest uploads slow to a
crawl of retransmissions or stall entirely, while the host's own TSO
traffic (gso_type SKB_GSO_TCPV4) is unaffected. On an n4 instance
(DQO-QPL) with a Cloud Hypervisor guest, a 64 MB upload from the guest
went from a 60 s timeout at ~0.9 MB/s to 0.19 s with this change, with
tx_dropped no longer increasing.

Host TCP with ECN is hit as well: gve advertises NETIF_F_TSO_ECN, so a
TSO packet carrying CWR has SKB_GSO_TCP_ECN set and is dropped too.

Restore the bitmask test that commit 1b9f75634441 ("gve: ignore
nonrelevant GSO type bits when processing TSO headers") introduced for
the same problem, keeping the UDP GSO support.

While here, reload shinfo after skb_cow_head(). If the head was cloned,
pskb_expand_head() moves skb_shared_info to the new head, and the
pointer cached at function entry can then refer to memory that another
clone frees.

Fixes: 014c607f86ab ("gve: add support for UDP GSO for DQO format")
Signed-off-by: Hannu Varjoranta <hannu@varjosoft.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ankit Garg <nktgrg@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Link: https://patch.msgid.link/20260925115237.56465-1-hannu@varjosoft.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions