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Date:   Sun,  5 Nov 2023 18:44:02 -0800
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Subject: [RFC PATCH v3 03/12] 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-arch@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linaro-mm-sig@lists.linaro.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>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        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>,
        Shakeel Butt <shakeelb@google.com>,
        Jeroen de Borst <jeroendb@google.com>,
        Praveen Kaligineedi <pkaligineedi@google.com>,
        Stanislav Fomichev <sdf@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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>

---

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

---
 Documentation/netlink/specs/netdev.yaml | 28 +++++++++++++++
 include/uapi/linux/netdev.h             | 10 ++++++
 net/core/netdev-genl-gen.c              | 14 ++++++++
 net/core/netdev-genl-gen.h              |  1 +
 net/core/netdev-genl.c                  |  6 ++++
 tools/include/uapi/linux/netdev.h       | 10 ++++++
 tools/net/ynl/generated/netdev-user.c   | 42 ++++++++++++++++++++++
 tools/net/ynl/generated/netdev-user.h   | 47 +++++++++++++++++++++++++
 8 files changed, 158 insertions(+)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 14511b13f305..2141c5f5c33e 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -86,6 +86,24 @@ attribute-sets:
              See Documentation/networking/xdp-rx-metadata.rst for more details.
         type: u64
         enum: xdp-rx-metadata
+  -
+    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: u32
+        multi-attr: true
+      -
+        name: dmabuf-fd
+        doc: dmabuf file descriptor to bind.
+        type: u32
 
 operations:
   list:
@@ -120,6 +138,16 @@ operations:
       doc: Notification about device configuration being changed.
       notify: dev-get
       mcgrp: mgmt
+    -
+      name: bind-rx
+      doc: Bind dmabuf to netdev
+      attribute-set: bind-dmabuf
+      do:
+        request:
+          attributes:
+            - ifindex
+            - dmabuf-fd
+            - queues
 
 mcast-groups:
   list:
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 2943a151d4f1..2cd367c498c7 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -64,11 +64,21 @@ enum {
 	NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1)
 };
 
+enum {
+	NETDEV_A_BIND_DMABUF_IFINDEX = 1,
+	NETDEV_A_BIND_DMABUF_QUEUES,
+	NETDEV_A_BIND_DMABUF_DMABUF_FD,
+
+	__NETDEV_A_BIND_DMABUF_MAX,
+	NETDEV_A_BIND_DMABUF_MAX = (__NETDEV_A_BIND_DMABUF_MAX - 1)
+};
+
 enum {
 	NETDEV_CMD_DEV_GET = 1,
 	NETDEV_CMD_DEV_ADD_NTF,
 	NETDEV_CMD_DEV_DEL_NTF,
 	NETDEV_CMD_DEV_CHANGE_NTF,
+	NETDEV_CMD_BIND_RX,
 
 	__NETDEV_CMD_MAX,
 	NETDEV_CMD_MAX = (__NETDEV_CMD_MAX - 1)
diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c
index ea9231378aa6..58300efaf4e5 100644
--- a/net/core/netdev-genl-gen.c
+++ b/net/core/netdev-genl-gen.c
@@ -15,6 +15,13 @@ 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),
 };
 
+/* 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] = { .type = NLA_U32, },
+};
+
 /* Ops table for netdev */
 static const struct genl_split_ops netdev_nl_ops[] = {
 	{
@@ -29,6 +36,13 @@ static const struct genl_split_ops netdev_nl_ops[] = {
 		.dumpit	= netdev_nl_dev_get_dumpit,
 		.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_CMD_CAP_DO,
+	},
 };
 
 static const struct genl_multicast_group netdev_nl_mcgrps[] = {
diff --git a/net/core/netdev-genl-gen.h b/net/core/netdev-genl-gen.h
index 7b370c073e7d..5aaeb435ec08 100644
--- a/net/core/netdev-genl-gen.h
+++ b/net/core/netdev-genl-gen.h
@@ -13,6 +13,7 @@
 
 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);
+int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info);
 
 enum {
 	NETDEV_NLGRP_MGMT,
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index fe61f85bcf33..59d3d512d9cc 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -129,6 +129,12 @@ int netdev_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
+/* 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 2943a151d4f1..2cd367c498c7 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -64,11 +64,21 @@ enum {
 	NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1)
 };
 
+enum {
+	NETDEV_A_BIND_DMABUF_IFINDEX = 1,
+	NETDEV_A_BIND_DMABUF_QUEUES,
+	NETDEV_A_BIND_DMABUF_DMABUF_FD,
+
+	__NETDEV_A_BIND_DMABUF_MAX,
+	NETDEV_A_BIND_DMABUF_MAX = (__NETDEV_A_BIND_DMABUF_MAX - 1)
+};
+
 enum {
 	NETDEV_CMD_DEV_GET = 1,
 	NETDEV_CMD_DEV_ADD_NTF,
 	NETDEV_CMD_DEV_DEL_NTF,
 	NETDEV_CMD_DEV_CHANGE_NTF,
+	NETDEV_CMD_BIND_RX,
 
 	__NETDEV_CMD_MAX,
 	NETDEV_CMD_MAX = (__NETDEV_CMD_MAX - 1)
diff --git a/tools/net/ynl/generated/netdev-user.c b/tools/net/ynl/generated/netdev-user.c
index b5ffe8cd1144..d5f4c6d4c2b2 100644
--- a/tools/net/ynl/generated/netdev-user.c
+++ b/tools/net/ynl/generated/netdev-user.c
@@ -18,6 +18,7 @@ static const char * const netdev_op_strmap[] = {
 	[NETDEV_CMD_DEV_ADD_NTF] = "dev-add-ntf",
 	[NETDEV_CMD_DEV_DEL_NTF] = "dev-del-ntf",
 	[NETDEV_CMD_DEV_CHANGE_NTF] = "dev-change-ntf",
+	[NETDEV_CMD_BIND_RX] = "bind-rx",
 };
 
 const char *netdev_op_str(int op)
@@ -72,6 +73,17 @@ struct ynl_policy_nest netdev_dev_nest = {
 	.table = netdev_dev_policy,
 };
 
+struct ynl_policy_attr netdev_bind_dmabuf_policy[NETDEV_A_BIND_DMABUF_MAX + 1] = {
+	[NETDEV_A_BIND_DMABUF_IFINDEX] = { .name = "ifindex", .type = YNL_PT_U32, },
+	[NETDEV_A_BIND_DMABUF_QUEUES] = { .name = "queues", .type = YNL_PT_U32, },
+	[NETDEV_A_BIND_DMABUF_DMABUF_FD] = { .name = "dmabuf-fd", .type = YNL_PT_U32, },
+};
+
+struct ynl_policy_nest netdev_bind_dmabuf_nest = {
+	.max_attr = NETDEV_A_BIND_DMABUF_MAX,
+	.table = netdev_bind_dmabuf_policy,
+};
+
 /* Common nested types */
 /* ============== NETDEV_CMD_DEV_GET ============== */
 /* NETDEV_CMD_DEV_GET - do */
@@ -197,6 +209,36 @@ void netdev_dev_get_ntf_free(struct netdev_dev_get_ntf *rsp)
 	free(rsp);
 }
 
+/* ============== NETDEV_CMD_BIND_RX ============== */
+/* NETDEV_CMD_BIND_RX - do */
+void netdev_bind_rx_req_free(struct netdev_bind_rx_req *req)
+{
+	free(req->queues);
+	free(req);
+}
+
+int netdev_bind_rx(struct ynl_sock *ys, struct netdev_bind_rx_req *req)
+{
+	struct nlmsghdr *nlh;
+	int err;
+
+	nlh = ynl_gemsg_start_req(ys, ys->family_id, NETDEV_CMD_BIND_RX, 1);
+	ys->req_policy = &netdev_bind_dmabuf_nest;
+
+	if (req->_present.ifindex)
+		mnl_attr_put_u32(nlh, NETDEV_A_BIND_DMABUF_IFINDEX, req->ifindex);
+	if (req->_present.dmabuf_fd)
+		mnl_attr_put_u32(nlh, NETDEV_A_BIND_DMABUF_DMABUF_FD, req->dmabuf_fd);
+	for (unsigned int i = 0; i < req->n_queues; i++)
+		mnl_attr_put_u32(nlh, NETDEV_A_BIND_DMABUF_QUEUES, req->queues[i]);
+
+	err = ynl_exec(ys, nlh, NULL);
+	if (err < 0)
+		return -1;
+
+	return 0;
+}
+
 static const struct ynl_ntf_info netdev_ntf_info[] =  {
 	[NETDEV_CMD_DEV_ADD_NTF] =  {
 		.alloc_sz	= sizeof(struct netdev_dev_get_ntf),
diff --git a/tools/net/ynl/generated/netdev-user.h b/tools/net/ynl/generated/netdev-user.h
index 4fafac879df3..3cf9096d733a 100644
--- a/tools/net/ynl/generated/netdev-user.h
+++ b/tools/net/ynl/generated/netdev-user.h
@@ -87,4 +87,51 @@ struct netdev_dev_get_ntf {
 
 void netdev_dev_get_ntf_free(struct netdev_dev_get_ntf *rsp);
 
+/* ============== NETDEV_CMD_BIND_RX ============== */
+/* NETDEV_CMD_BIND_RX - do */
+struct netdev_bind_rx_req {
+	struct {
+		__u32 ifindex:1;
+		__u32 dmabuf_fd:1;
+	} _present;
+
+	__u32 ifindex;
+	__u32 dmabuf_fd;
+	unsigned int n_queues;
+	__u32 *queues;
+};
+
+static inline struct netdev_bind_rx_req *netdev_bind_rx_req_alloc(void)
+{
+	return calloc(1, sizeof(struct netdev_bind_rx_req));
+}
+void netdev_bind_rx_req_free(struct netdev_bind_rx_req *req);
+
+static inline void
+netdev_bind_rx_req_set_ifindex(struct netdev_bind_rx_req *req, __u32 ifindex)
+{
+	req->_present.ifindex = 1;
+	req->ifindex = ifindex;
+}
+static inline void
+netdev_bind_rx_req_set_dmabuf_fd(struct netdev_bind_rx_req *req,
+				 __u32 dmabuf_fd)
+{
+	req->_present.dmabuf_fd = 1;
+	req->dmabuf_fd = dmabuf_fd;
+}
+static inline void
+__netdev_bind_rx_req_set_queues(struct netdev_bind_rx_req *req, __u32 *queues,
+				unsigned int n_queues)
+{
+	free(req->queues);
+	req->queues = queues;
+	req->n_queues = n_queues;
+}
+
+/*
+ * Bind dmabuf to netdev
+ */
+int netdev_bind_rx(struct ynl_sock *ys, struct netdev_bind_rx_req *req);
+
 #endif /* _LINUX_NETDEV_GEN_H */
-- 
2.42.0.869.gea05f2083d-goog