[PATCH] octeontx2-pf: macsec: Fix incorrect MTU size in TX secy policy

[PATCH] octeontx2-pf: macsec: Fix incorrect MTU size in TX secy policy

[Subbaraya Sundeep]

Underlying real device MTU plus the L2 header length has to
be configured in TX secy policy because hardware expects the
mtu to be programmed is outgoing maximum transmission unit from
MCS block i.e, including L2 header, SecTag and ICV.

Fixes: c54ffc73601c ("octeontx2-pf: mcs: Introduce MACSEC hardware offloading")
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
---
 drivers/net/ethernet/marvell/octeontx2/nic/cn10k_macsec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/cn10k_macsec.c b/drivers/net/ethernet/marvell/octeontx2/nic/cn10k_macsec.c
index f3b9daf..4c7e0f3 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/cn10k_macsec.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/cn10k_macsec.c
@@ -531,7 +531,8 @@ static int cn10k_mcs_write_tx_secy(struct otx2_nic *pfvf,
 	if (sw_tx_sc->encrypt)
 		sectag_tci |= (MCS_TCI_E | MCS_TCI_C);
 
-	policy = FIELD_PREP(MCS_TX_SECY_PLCY_MTU, secy->netdev->mtu);
+	policy = FIELD_PREP(MCS_TX_SECY_PLCY_MTU,
+			    pfvf->netdev->mtu + OTX2_ETH_HLEN);
 	/* Write SecTag excluding AN bits(1..0) */
 	policy |= FIELD_PREP(MCS_TX_SECY_PLCY_ST_TCI, sectag_tci >> 2);
 	policy |= FIELD_PREP(MCS_TX_SECY_PLCY_ST_OFFSET, tag_offset);
-- 
2.7.4

Re: [PATCH] octeontx2-pf: macsec: Fix incorrect MTU size in TX secy policy

[Simon Horman]

On Wed, May 07, 2025 at 10:44:20PM +0530, Subbaraya Sundeep wrote:
> Underlying real device MTU plus the L2 header length has to
> be configured in TX secy policy because hardware expects the
> mtu to be programmed is outgoing maximum transmission unit from
> MCS block i.e, including L2 header, SecTag and ICV.

Hi Subbaraya,

I think it would be good to include an explanation of how
this bug manifests.

And please target fixes for bugs present in net at net.

Subject: [PATCH net] ...

> 
> Fixes: c54ffc73601c ("octeontx2-pf: mcs: Introduce MACSEC hardware offloading")
> Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>

...

-- 
pw-bot: changes-requested

Re: [PATCH] octeontx2-pf: macsec: Fix incorrect MTU size in TX secy policy

[Subbaraya Sundeep]

Hi Simon,

On 2025-05-08 at 19:00:03, Simon Horman (horms@kernel.org) wrote:
> On Wed, May 07, 2025 at 10:44:20PM +0530, Subbaraya Sundeep wrote:
> > Underlying real device MTU plus the L2 header length has to
> > be configured in TX secy policy because hardware expects the
> > mtu to be programmed is outgoing maximum transmission unit from
> > MCS block i.e, including L2 header, SecTag and ICV.
> 
> Hi Subbaraya,
> 
> I think it would be good to include an explanation of how
> this bug manifests.
> 
> And please target fixes for bugs present in net at net.
> 
> Subject: [PATCH net] ...
> 
Yes I missed the net in subject. I will send v2.

Thanks,
Sundeep
> > 
> > Fixes: c54ffc73601c ("octeontx2-pf: mcs: Introduce MACSEC hardware offloading")
> > Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
> 
> ...
> 
> -- 
> pw-bot: changes-requested