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Wed, 08 Dec 2021 05:07:43 -0800 (PST) X-Google-Smtp-Source: ABdhPJzLGTWtzqIz86k63en8xkyrd24lq8MrAX2dhh2Y1hgZTXXwopmFZg1z03jTCqp8uFJnAY2yrw== X-Received: by 2002:a17:906:4aca:: with SMTP id u10mr7396805ejt.305.1638968862076; Wed, 08 Dec 2021 05:07:42 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id e15sm1949569edq.46.2021.12.08.05.07.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Dec 2021 05:07:41 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 48C0E180441; Wed, 8 Dec 2021 14:07:40 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Lorenzo Bianconi , Zvi Effron Cc: Jesper Dangaard Brouer , Lorenzo Bianconi , bpf@vger.kernel.org, netdev@vger.kernel.org, brouer@redhat.com, davem@davemloft.net, kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net, shayagr@amazon.com, john.fastabend@gmail.com, dsahern@kernel.org, echaudro@redhat.com, jasowang@redhat.com, alexander.duyck@gmail.com, saeed@kernel.org, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, tirthendu.sarkar@intel.com Subject: Re: [PATCH v19 bpf-next 23/23] xdp: disable XDP_REDIRECT for xdp multi-buff In-Reply-To: References: <88f9b4e9-9074-a507-426d-7c947f1e2b13@redhat.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Wed, 08 Dec 2021 14:07:40 +0100 Message-ID: <87mtlbxn1f.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Lorenzo Bianconi writes: >> On Mon, Dec 6, 2021 at 11:11 AM Jesper Dangaard Brouer >> wrote: >> > >> > On 30/11/2021 12.53, Lorenzo Bianconi wrote: >> > > XDP_REDIRECT is not fully supported yet for xdp multi-buff since not >> > > all XDP capable drivers can map non-linear xdp_frame in ndo_xdp_xmit >> > > so disable it for the moment. >> > > >> > > Signed-off-by: Lorenzo Bianconi >> > > --- >> > > net/core/filter.c | 7 +++++++ >> > > 1 file changed, 7 insertions(+) >> > > >> > > diff --git a/net/core/filter.c b/net/core/filter.c >> > > index b70725313442..a87d835d1122 100644 >> > > --- a/net/core/filter.c >> > > +++ b/net/core/filter.c >> > > @@ -4189,6 +4189,13 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp, >> > > struct bpf_map *map; >> > > int err; >> > > >> > > + /* XDP_REDIRECT is not fully supported yet for xdp multi-buff since >> > > + * not all XDP capable drivers can map non-linear xdp_frame in >> > > + * ndo_xdp_xmit. >> > > + */ >> > > + if (unlikely(xdp_buff_is_mb(xdp))) >> > > + return -EOPNOTSUPP; >> > > + >> > >> > This approach also exclude 'cpumap' use-case, which you AFAIK have added >> > MB support for in this patchset. >> > >> > Generally this check is hopefully something we can remove again, once >> > drivers add MB ndo_xdp_xmit support. >> > >> >> What happens in the future when a new driver is added without (in its intial >> version) MB ndo_xdp_xmit support? Is MB support for ndo_xdp_xmit going to be a >> requirement for a driver (with ndo_xdp_xmit) to be accepted to the kernel? > > I think the optimal solution would be export the driver XDP capabilities (AFAIK > there is an ogoing effort for this, but it is not available yet). Until that materialises I think we can at least require new drivers to check the MB flag and drop the frame if it doesn't know what to do with it. A follow-on patch could also just update all the existing drivers to do this and then remove this check... -Toke