Re: [RFC PATCH net-next v5 05/14] netdev: netdevice devmem allocator

From: Mina Almasry <almasrymina@google.com>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"Martin KaFai Lau" <martin.lau@linux.dev>,
	"Song Liu" <song@kernel.org>,
	"Yonghong Song" <yonghong.song@linux.dev>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"KP Singh" <kpsingh@kernel.org>,
	"Stanislav Fomichev" <sdf@google.com>,
	"Hao Luo" <haoluo@google.com>, "Jiri Olsa" <jolsa@kernel.org>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-alpha@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org, bpf@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	"David S. Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Ivan Kokshaysky" <ink@jurassic.park.msu.ru>,
	"Matt Turner" <mattst88@gmail.com>,
	"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	"Helge Deller" <deller@gmx.de>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Masami Hiramatsu" <mhiramat@kernel.org>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andrii@kernel.org>,
	"David Ahern" <dsahern@kernel.org>,
	"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
	"Shuah Khan" <shuah@kernel.org>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"David Wei" <dw@davidwei.uk>, "Jason Gunthorpe" <jgg@ziepe.ca>,
	"Yunsheng Lin" <linyunsheng@huawei.com>,
	"Shailend Chand" <shailend@google.com>,
	"Harshitha Ramamurthy" <hramamurthy@google.com>,
	"Shakeel Butt" <shakeelb@google.com>,
	"Jeroen de Borst" <jeroendb@google.com>,
	"Praveen Kaligineedi" <pkaligineedi@google.com>,
	"Willem de Bruijn" <willemb@google.com>,
	"Kaiyuan Zhang" <kaiyuanz@google.com>
Subject: Re: [RFC PATCH net-next v5 05/14] netdev: netdevice devmem allocator
Date: Tue, 13 Feb 2024 12:01:38 -0800	[thread overview]
Message-ID: <CAHS8izOJMEtC1a26yJGMzV9jsX9TtE2xWXzWQ6qSi4ynXnr2Wg@mail.gmail.com> (raw)
In-Reply-To: <94ff0733-5987-4bf5-a53c-011e03aa6323@gmail.com>

On Tue, Feb 13, 2024 at 5:24 AM Pavel Begunkov <asml.silence@gmail.com> wrote:
>
> On 12/18/23 02:40, Mina Almasry wrote:
> > Implement netdev devmem allocator. The allocator takes a given struct
> > netdev_dmabuf_binding as input and allocates net_iov from that
> > binding.
> >
> > The allocation simply delegates to the binding's genpool for the
> > allocation logic and wraps the returned memory region in a net_iov
> > struct.
> >
> > Signed-off-by: Willem de Bruijn <willemb@google.com>
> > Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com>
> > Signed-off-by: Mina Almasry <almasrymina@google.com>
> >
> > ---
> >
> > v1:
> > - Rename devmem -> dmabuf (David).
> >
> > ---
> >   include/net/devmem.h | 12 ++++++++++++
> >   include/net/netmem.h | 26 ++++++++++++++++++++++++++
> >   net/core/dev.c       | 38 ++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 76 insertions(+)
> >
> ...
> > diff --git a/include/net/netmem.h b/include/net/netmem.h
> > index 45eb42d9990b..7fce2efc8707 100644
> > --- a/include/net/netmem.h
> > +++ b/include/net/netmem.h
> > @@ -14,8 +14,34 @@
> >
> >   struct net_iov {
> >       struct dmabuf_genpool_chunk_owner *owner;
> > +     unsigned long dma_addr;
> >   };
> >
> > +static inline struct dmabuf_genpool_chunk_owner *
> > +net_iov_owner(const struct net_iov *niov)
> > +{
> > +     return niov->owner;
> > +}
> > +
> > +static inline unsigned int net_iov_idx(const struct net_iov *niov)
> > +{
> > +     return niov - net_iov_owner(niov)->niovs;
> > +}
> > +
> > +static inline dma_addr_t net_iov_dma_addr(const struct net_iov *niov)
> > +{
> > +     struct dmabuf_genpool_chunk_owner *owner = net_iov_owner(niov);
> > +
> > +     return owner->base_dma_addr +
> > +            ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT);
>
> Looks like it should have been niov->dma_addr
>

Yes, indeed. Thanks for catching.

> > +}
> > +
> > +static inline struct netdev_dmabuf_binding *
> > +net_iov_binding(const struct net_iov *niov)
> > +{
> > +     return net_iov_owner(niov)->binding;
> > +}
> > +
> >   /* netmem */
> >
> >   struct netmem {
> ...
>
> --
> Pavel Begunkov

-- 
Thanks,
Mina