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Date: Tue, 26 Mar 2024 15:50:34 -0700
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Subject: [RFC PATCH net-next v7 03/14] net: netdev netlink api to bind dma-buf
 to a net device
From: Mina Almasry <almasrymina@google.com>
To: 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, 
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	linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, 
	dri-devel@lists.freedesktop.org
Cc: Mina Almasry <almasrymina@google.com>, "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>, 
	Andreas Larsson <andreas@gaisler.com>, Jesper Dangaard Brouer <hawk@kernel.org>, 
	Ilias Apalodimas <ilias.apalodimas@linaro.org>, Steven Rostedt <rostedt@goodmis.org>, 
	Masami Hiramatsu <mhiramat@kernel.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, 
	Arnd Bergmann <arnd@arndb.de>, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, 
	Andrii Nakryiko <andrii@kernel.org>, Martin KaFai Lau <martin.lau@linux.dev>, 
	Eduard Zingerman <eddyz87@gmail.com>, 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>, Steffen Klassert <steffen.klassert@secunet.com>, 
	Herbert Xu <herbert@gondor.apana.org.au>, David Ahern <dsahern@kernel.org>, 
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>, Shuah Khan <shuah@kernel.org>, 
	Sumit Semwal <sumit.semwal@linaro.org>, 
	"=?UTF-8?q?Christian=20K=C3=B6nig?=" <christian.koenig@amd.com>, Pavel Begunkov <asml.silence@gmail.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 <shakeel.butt@linux.dev>, Jeroen de Borst <jeroendb@google.com>, 
	Praveen Kaligineedi <pkaligineedi@google.com>
Content-Type: text/plain; charset="UTF-8"

API takes the dma-buf fd as input, and binds it to the netdevice. The
user can specify the rx queues to bind the dma-buf to.

Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>

---

v7:
- Use flags: [ admin-perm ] instead of a CAP_NET_ADMIN check.

Changes in v1:
- Add rx-queue-type to distingish rx from tx (Jakub)
- Return dma-buf ID from netlink API (David, Stan)

Changes in RFC-v3:
- Support binding multiple rx rx-queues

---
 Documentation/netlink/specs/netdev.yaml | 53 +++++++++++++++++++++++++
 include/uapi/linux/netdev.h             | 19 +++++++++
 net/core/netdev-genl-gen.c              | 19 +++++++++
 net/core/netdev-genl-gen.h              |  2 +
 net/core/netdev-genl.c                  |  6 +++
 tools/include/uapi/linux/netdev.h       | 19 +++++++++
 6 files changed, 118 insertions(+)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 76352dbd2be4..275d1faa87a6 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -268,6 +268,45 @@ attribute-sets:
         name: napi-id
         doc: ID of the NAPI instance which services this queue.
         type: u32
+  -
+    name: queue-dmabuf
+    attributes:
+      -
+        name: type
+        doc: rx or tx queue
+        type: u8
+        enum: queue-type
+      -
+        name: idx
+        doc: queue index
+        type: u32
+
+  -
+    name: bind-dmabuf
+    attributes:
+      -
+        name: ifindex
+        doc: netdev ifindex to bind the dma-buf to.
+        type: u32
+        checks:
+          min: 1
+      -
+        name: queues
+        doc: receive queues to bind the dma-buf to.
+        type: nest
+        nested-attributes: queue-dmabuf
+        multi-attr: true
+      -
+        name: dmabuf-fd
+        doc: dmabuf file descriptor to bind.
+        type: u32
+      -
+        name: dmabuf-id
+        doc: id of the dmabuf binding
+        type: u32
+        checks:
+          min: 1
+
 
   -
     name: qstats
@@ -457,6 +496,20 @@ operations:
           attributes:
             - ifindex
         reply: *queue-get-op
+    -
+      name: bind-rx
+      doc: Bind dmabuf to netdev
+      attribute-set: bind-dmabuf
+      flags: [ admin-perm ]
+      do:
+        request:
+          attributes:
+            - ifindex
+            - dmabuf-fd
+            - queues
+        reply:
+          attributes:
+            - dmabuf-id
     -
       name: napi-get
       doc: Get information about NAPI instances configured on the system.
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index bb65ee840cda..c5b959a0ed6c 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -136,6 +136,24 @@ enum {
 	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
 };
 
+enum {
+	NETDEV_A_QUEUE_DMABUF_TYPE = 1,
+	NETDEV_A_QUEUE_DMABUF_IDX,
+
+	__NETDEV_A_QUEUE_DMABUF_MAX,
+	NETDEV_A_QUEUE_DMABUF_MAX = (__NETDEV_A_QUEUE_DMABUF_MAX - 1)
+};
+
+enum {
+	NETDEV_A_BIND_DMABUF_IFINDEX = 1,
+	NETDEV_A_BIND_DMABUF_QUEUES,
+	NETDEV_A_BIND_DMABUF_DMABUF_FD,
+	NETDEV_A_BIND_DMABUF_DMABUF_ID,
+
+	__NETDEV_A_BIND_DMABUF_MAX,
+	NETDEV_A_BIND_DMABUF_MAX = (__NETDEV_A_BIND_DMABUF_MAX - 1)
+};
+
 enum {
 	NETDEV_A_QSTATS_IFINDEX = 1,
 	NETDEV_A_QSTATS_QUEUE_TYPE,
@@ -162,6 +180,7 @@ enum {
 	NETDEV_CMD_PAGE_POOL_CHANGE_NTF,
 	NETDEV_CMD_PAGE_POOL_STATS_GET,
 	NETDEV_CMD_QUEUE_GET,
+	NETDEV_CMD_BIND_RX,
 	NETDEV_CMD_NAPI_GET,
 	NETDEV_CMD_QSTATS_GET,
 
diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c
index 8d8ace9ef87f..bbaaa1b36b5b 100644
--- a/net/core/netdev-genl-gen.c
+++ b/net/core/netdev-genl-gen.c
@@ -27,6 +27,11 @@ const struct nla_policy netdev_page_pool_info_nl_policy[NETDEV_A_PAGE_POOL_IFIND
 	[NETDEV_A_PAGE_POOL_IFINDEX] = NLA_POLICY_FULL_RANGE(NLA_U32, &netdev_a_page_pool_ifindex_range),
 };
 
+const struct nla_policy netdev_queue_dmabuf_nl_policy[NETDEV_A_QUEUE_DMABUF_IDX + 1] = {
+	[NETDEV_A_QUEUE_DMABUF_TYPE] = NLA_POLICY_MAX(NLA_U8, 1),
+	[NETDEV_A_QUEUE_DMABUF_IDX] = { .type = NLA_U32, },
+};
+
 /* NETDEV_CMD_DEV_GET - do */
 static const struct nla_policy netdev_dev_get_nl_policy[NETDEV_A_DEV_IFINDEX + 1] = {
 	[NETDEV_A_DEV_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1),
@@ -58,6 +63,13 @@ static const struct nla_policy netdev_queue_get_dump_nl_policy[NETDEV_A_QUEUE_IF
 	[NETDEV_A_QUEUE_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1),
 };
 
+/* NETDEV_CMD_BIND_RX - do */
+static const struct nla_policy netdev_bind_rx_nl_policy[NETDEV_A_BIND_DMABUF_DMABUF_FD + 1] = {
+	[NETDEV_A_BIND_DMABUF_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1),
+	[NETDEV_A_BIND_DMABUF_DMABUF_FD] = { .type = NLA_U32, },
+	[NETDEV_A_BIND_DMABUF_QUEUES] = NLA_POLICY_NESTED(netdev_queue_dmabuf_nl_policy),
+};
+
 /* NETDEV_CMD_NAPI_GET - do */
 static const struct nla_policy netdev_napi_get_do_nl_policy[NETDEV_A_NAPI_ID + 1] = {
 	[NETDEV_A_NAPI_ID] = { .type = NLA_U32, },
@@ -129,6 +141,13 @@ static const struct genl_split_ops netdev_nl_ops[] = {
 		.maxattr	= NETDEV_A_QUEUE_IFINDEX,
 		.flags		= GENL_CMD_CAP_DUMP,
 	},
+	{
+		.cmd		= NETDEV_CMD_BIND_RX,
+		.doit		= netdev_nl_bind_rx_doit,
+		.policy		= netdev_bind_rx_nl_policy,
+		.maxattr	= NETDEV_A_BIND_DMABUF_DMABUF_FD,
+		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
+	},
 	{
 		.cmd		= NETDEV_CMD_NAPI_GET,
 		.doit		= netdev_nl_napi_get_doit,
diff --git a/net/core/netdev-genl-gen.h b/net/core/netdev-genl-gen.h
index 4db40fd5b4a9..ca5a0983f283 100644
--- a/net/core/netdev-genl-gen.h
+++ b/net/core/netdev-genl-gen.h
@@ -13,6 +13,7 @@
 
 /* Common nested types */
 extern const struct nla_policy netdev_page_pool_info_nl_policy[NETDEV_A_PAGE_POOL_IFINDEX + 1];
+extern const struct nla_policy netdev_queue_dmabuf_nl_policy[NETDEV_A_QUEUE_DMABUF_IDX + 1];
 
 int netdev_nl_dev_get_doit(struct sk_buff *skb, struct genl_info *info);
 int netdev_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
@@ -26,6 +27,7 @@ int netdev_nl_page_pool_stats_get_dumpit(struct sk_buff *skb,
 int netdev_nl_queue_get_doit(struct sk_buff *skb, struct genl_info *info);
 int netdev_nl_queue_get_dumpit(struct sk_buff *skb,
 			       struct netlink_callback *cb);
+int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info);
 int netdev_nl_napi_get_doit(struct sk_buff *skb, struct genl_info *info);
 int netdev_nl_napi_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
 int netdev_nl_qstats_get_dumpit(struct sk_buff *skb,
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 7004b3399c2b..67711d29d0d4 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -674,6 +674,12 @@ int netdev_nl_qstats_get_dumpit(struct sk_buff *skb,
 	return err;
 }
 
+/* Stub */
+int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	return 0;
+}
+
 static int netdev_genl_netdevice_event(struct notifier_block *nb,
 				       unsigned long event, void *ptr)
 {
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index bb65ee840cda..c5b959a0ed6c 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -136,6 +136,24 @@ enum {
 	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
 };
 
+enum {
+	NETDEV_A_QUEUE_DMABUF_TYPE = 1,
+	NETDEV_A_QUEUE_DMABUF_IDX,
+
+	__NETDEV_A_QUEUE_DMABUF_MAX,
+	NETDEV_A_QUEUE_DMABUF_MAX = (__NETDEV_A_QUEUE_DMABUF_MAX - 1)
+};
+
+enum {
+	NETDEV_A_BIND_DMABUF_IFINDEX = 1,
+	NETDEV_A_BIND_DMABUF_QUEUES,
+	NETDEV_A_BIND_DMABUF_DMABUF_FD,
+	NETDEV_A_BIND_DMABUF_DMABUF_ID,
+
+	__NETDEV_A_BIND_DMABUF_MAX,
+	NETDEV_A_BIND_DMABUF_MAX = (__NETDEV_A_BIND_DMABUF_MAX - 1)
+};
+
 enum {
 	NETDEV_A_QSTATS_IFINDEX = 1,
 	NETDEV_A_QSTATS_QUEUE_TYPE,
@@ -162,6 +180,7 @@ enum {
 	NETDEV_CMD_PAGE_POOL_CHANGE_NTF,
 	NETDEV_CMD_PAGE_POOL_STATS_GET,
 	NETDEV_CMD_QUEUE_GET,
+	NETDEV_CMD_BIND_RX,
 	NETDEV_CMD_NAPI_GET,
 	NETDEV_CMD_QSTATS_GET,
 
-- 
2.44.0.396.g6e790dbe36-goog