netdev - Re: [PATCH 2/5] xfrm: Pass UDP encapsulation in TX packet offload

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Date: Tue, 12 Mar 2024 12:20:49 +0100
From: Steffen Klassert <steffen.klassert@...unet.com>
To: Leon Romanovsky <leon@...nel.org>
CC: Paolo Abeni <pabeni@...hat.com>, David Miller <davem@...emloft.net>,
	"Jakub Kicinski" <kuba@...nel.org>, Herbert Xu <herbert@...dor.apana.org.au>,
	<netdev@...r.kernel.org>
Subject: Re: [PATCH 2/5] xfrm: Pass UDP encapsulation in TX packet offload

On Tue, Mar 12, 2024 at 01:15:28PM +0200, Leon Romanovsky wrote:
> On Tue, Mar 12, 2024 at 07:20:06AM +0100, Steffen Klassert wrote:
> > On Mon, Mar 11, 2024 at 05:25:03PM +0100, Paolo Abeni wrote:
> > > Hi,
> > > 
> > > On Wed, 2024-03-06 at 11:04 +0100, Steffen Klassert wrote:
> > > > From: Leon Romanovsky <leonro@...dia.com>
> > > > 
> > > > In addition to citied commit in Fixes line, allow UDP encapsulation in
> > > > TX path too.
> > > > 
> > > > Fixes: 89edf40220be ("xfrm: Support UDP encapsulation in packet offload mode")
> > > > CC: Steffen Klassert <steffen.klassert@...unet.com>
> > > > Reported-by: Mike Yu <yumike@...gle.com>
> > > > Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> > > > Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
> > > > Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
> > > 
> > > This is causing self-test failures:
> > > 
> > > https://netdev.bots.linux.dev/flakes.html?tn-needle=pmtu-sh
> > > 
> > > reverting this change locally resolves the issue.
> > > 
> > > @Leon, @Steffen: could you please have a look?
> > 
> > Looks like the check for x->encap was removed unconditionally.
> > I should just be removed when XFRM_DEV_OFFLOAD_PACKET is set,
> > otherwise we might create a GSO packet with UPD encapsulation.
> > 
> > Leon?
> 
> Right, I missed IPsec SW path, that x->encap check can be removed
> in packet offload because HW supports it and in crypto offload, because
> there is a check in xfrm_dev_state_add() to prevent it.
> 
> What about this fix?
> 
> diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
> index 653e51ae3964..6e3e5a09cfeb 100644
> --- a/net/xfrm/xfrm_device.c
> +++ b/net/xfrm/xfrm_device.c
> @@ -407,7 +407,7 @@ bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x)
>         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
>         struct net_device *dev = x->xso.dev;
> 
> -       if (!x->type_offload)
> +       if (!x->type_offload || x->xso.type == XFRM_DEV_OFFLOAD_UNSPECIFIED)
>                 return false;

Then we can't generate GSO packets for the SW path anymore. We just need
to reject UDP enacpsulation in SW here.