memory-provider: dmabuf devmem memory provider

Implement a memory provider that allocates dmabuf devmem in the form of
net_iov.

The provider receives a reference to the struct netdev_dmabuf_binding
via the pool->mp_priv pointer. The driver needs to set this pointer for
the provider in the net_iov.

The provider obtains a reference on the netdev_dmabuf_binding which
guarantees the binding and the underlying mapping remains alive until
the provider is destroyed.

Usage of PP_FLAG_DMA_MAP is required for this memory provide such that
the page_pool can provide the driver with the dma-addrs of the devmem.

Support for PP_FLAG_DMA_SYNC_DEV is omitted for simplicity & p.order !=
0.

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>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20240910171458.219195-7-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 26 insertions, 1 deletions

diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
index 3a3277ba167b..cd6267ba6fa3 100644
--- a/net/core/page_pool_user.c
+++ b/net/core/page_pool_user.c
@@ -4,8 +4,9 @@
 #include <linux/netdevice.h>
 #include <linux/xarray.h>
 #include <net/net_debug.h>
-#include <net/page_pool/types.h>
+#include <net/netdev_rx_queue.h>
 #include <net/page_pool/helpers.h>
+#include <net/page_pool/types.h>
 #include <net/sock.h>
 
 #include "page_pool_priv.h"
@@ -344,6 +345,30 @@ void page_pool_unlist(struct page_pool *pool)
 	mutex_unlock(&page_pools_lock);
 }
 
+int page_pool_check_memory_provider(struct net_device *dev,
+				    struct netdev_rx_queue *rxq)
+{
+	struct net_devmem_dmabuf_binding *binding = rxq->mp_params.mp_priv;
+	struct page_pool *pool;
+	struct hlist_node *n;
+
+	if (!binding)
+		return 0;
+
+	mutex_lock(&page_pools_lock);
+	hlist_for_each_entry_safe(pool, n, &dev->page_pools, user.list) {
+		if (pool->mp_priv != binding)
+			continue;
+
+		if (pool->slow.queue_idx == get_netdev_rx_queue_index(rxq)) {
+			mutex_unlock(&page_pools_lock);
+			return 0;
+		}
+	}
+	mutex_unlock(&page_pools_lock);
+	return -ENODATA;
+}
+
 static void page_pool_unreg_netdev_wipe(struct net_device *netdev)
 {
 	struct page_pool *pool;