[PATCH v11 2/4] virtio-net: clarify DATA_VALID semantic for encap protos.

Paolo Abeni
2024-11-27T09:37:03Z

DATA_VALID allows offloading a single checksum level, leaving
unspecified which header checksum is offloaded when one or more
encapsulated protocols are present.

In such a case, the only option usable from the guest OS is
offloading the outermost checksum. That also matches the existing
implementation.

Explicitly state such the constraint, to remove any ambiguity and
make later changes more straightforward.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
device-types/net/description.tex | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/device-types/net/description.tex b/device-types/net/description.tex
index 3434a31..77bd847 100644
--- a/device-types/net/description.tex
+++ b/device-types/net/description.tex
@@ -994,8 +994,8 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
If the VIRTIO_NET_F_GUEST_CSUM feature has been negotiated, the
device MAY set the VIRTIO_NET_HDR_F_DATA_VALID bit in
\field{flags}, if so, the device MUST validate the packet
-checksum (in case of multiple encapsulated protocols, one level
-of checksums is validated).
+checksum. One level of checksum is validated: in case of multiple
+encapsulated protocols the outermost one.

\drivernormative{\paragraph}{Processing of Incoming
Packets}{Device Types / Network Device / Device Operation /
--
2.45.2