netdev: support binding dma-buf to netdevice

Add a netdev_dmabuf_binding struct which represents the
dma-buf-to-netdevice binding. The netlink API will bind the dma-buf to
rx queues on the netdevice. On the binding, the dma_buf_attach
& dma_buf_map_attachment will occur. The entries in the sg_table from
mapping will be inserted into a genpool to make it ready
for allocation.

The chunks in the genpool are owned by a dmabuf_chunk_owner struct which
holds the dma-buf offset of the base of the chunk and the dma_addr of
the chunk. Both are needed to use allocations that come from this chunk.

We create a new type that represents an allocation from the genpool:
net_iov. We setup the net_iov allocation size in the
genpool to PAGE_SIZE for simplicity: to match the PAGE_SIZE normally
allocated by the page pool and given to the drivers.

The user can unbind the dmabuf from the netdevice by closing the netlink
socket that established the binding. We do this so that the binding is
automatically unbound even if the userspace process crashes.

The binding and unbinding leaves an indicator in struct netdev_rx_queue
that the given queue is bound, and the binding is actuated by resetting
the rx queue using the queue API.

The netdev_dmabuf_binding struct is refcounted, and releases its
resources only when all the refs are released.

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>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> # excluding netlink
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20240910171458.219195-4-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 16 insertions, 0 deletions

diff --git a/include/net/netdev_rx_queue.h b/include/net/netdev_rx_queue.h
index e78ca52d67fb..ac34f5fb4f71 100644
--- a/include/net/netdev_rx_queue.h
+++ b/include/net/netdev_rx_queue.h
@@ -6,6 +6,7 @@
 #include <linux/netdevice.h>
 #include <linux/sysfs.h>
 #include <net/xdp.h>
+#include <net/page_pool/types.h>
 
 /* This structure contains an instance of an RX queue. */
 struct netdev_rx_queue {
@@ -25,6 +26,7 @@ struct netdev_rx_queue {
 	 * Readers and writers must hold RTNL
 	 */
 	struct napi_struct		*napi;
+	struct pp_memory_provider_params mp_params;
 } ____cacheline_aligned_in_smp;
 
 /*
diff --git a/include/net/netmem.h b/include/net/netmem.h
index 46cc9b89ac79..c23e224dd6a0 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -8,6 +8,14 @@
 #ifndef _NET_NETMEM_H
 #define _NET_NETMEM_H
 
+/* net_iov */
+
+struct net_iov {
+	struct dmabuf_genpool_chunk_owner *owner;
+};
+
+/* netmem */
+
 /**
  * typedef netmem_ref - a nonexistent type marking a reference to generic
  * network memory.
diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 50569fed7868..4afd6dd56351 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -139,6 +139,10 @@ struct page_pool_stats {
  */
 #define PAGE_POOL_FRAG_GROUP_ALIGN	(4 * sizeof(long))
 
+struct pp_memory_provider_params {
+	void *mp_priv;
+};
+
 struct page_pool {
 	struct page_pool_params_fast p;
 
@@ -197,6 +201,8 @@ struct page_pool {
 	 */
 	struct ptr_ring ring;
 
+	void *mp_priv;
+
 #ifdef CONFIG_PAGE_POOL_STATS
 	/* recycle stats are per-cpu to avoid locking */
 	struct page_pool_recycle_stats __percpu *recycle_stats;