Re: [PATCH net-next V4 14/14] selftests: drv-net: Add PSP HW GRO conformance tests

[Cosmin Ratiu <cratiu@nvidia.com>]

On Tue, 2026-09-08 at 19:22 -0400, Daniel Zahka wrote:
> On Tue Sep 8, 2026 at 2:52 AM EDT, Tariq Toukan wrote:
> > From: Cosmin Ratiu <cratiu@nvidia.com>
> > 
> > Add PSP conformance tests using the same gro helper binary as other
> > gro
> > tests , but in --psp mode. SPIs are procured by psp_gro.py from a
> > real
> > PSP device and handed off to the gro sender & receiver. The sender
> > crafts and encrypts packets in software, the receiver relies fully
> > on
> > the HW to decrypt, decapsulate and do HW GRO.
> > 
> > Because the NIC decrypts and decapsulates before the frames reach
> > the
> > receiver AF_PACKET tap, the gro receiver sees the plain frames and
> > the
> > assertions remain exactly the same as other gro tests.
> > 
> > So these tests verify, at length, that the device does PSP HW-GRO
> > the
> > same way as plain TCP.
> > 
> > Additional PSP-specific tests are defined to check that GRO doesn't
> > merge packets across PSP versions, SPIs, encryption-status, etc.
> > 
> > Some gro tests are not included because they don't work:
> > - ip_csum: the checksum is recomputed by psp_dev_rcv().
> 
> psp_dev_rcv() isn't on the hw gro path for mlx5, right?

You're right, that's a bogus argument, sorry.
The truth was that the encap support in gro.c was recomputing the IP
checksum, sabotaging the bad csum test... Will be fixed in the next
version.


> > - tcp_csum: packets are marked with CHECKSUM_UNNECESSARY.
> 
> this also seems strange to me as the hw gro engine and its decision
> to
> coalesce two packets sits upstream of this skb->ip_summed
> determination
> in the driver, right?

Another weak argument from my side, sorry. I will add the test back.

> 
> > - ip_frag4/ip_frag6: PSP is incompatible with IP fragmentation.
> > - IPv6 extension header tests: PSP doesn't deal with IPv6 ext
> > headers.
> > 
> > Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
> > Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
> > Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
> > ---
> ...
> > +
> > +@ksft_variants(_ip_variants())
> > +def test_psp_ver_diff(cfg, protocol):
> > +    """Frames from two different PSP versions must not
> > coalesce."""
> > +    init_psp_dev(cfg)
> > +    if len(cfg.psp_info['psp-versions-cap']) < 2:
> 
> nit: what the above checks is slightly different than what the _run()
> below uses, e.g. dev supports versions 0 and 2.

Will drop this check.

> 
> > +        raise KsftSkipEx("Device supports a single PSP version")
> > +
> > +    _run(cfg, "psp_ver_diff", protocol, [0, 1])
> > +
> 
> couple of minor comments:
> 
> Reviewed-by: Daniel Zahka <daniel.zahka@gmail.com>

Thank you for the review!

Cosmin.