On 12/18/23 02:40, Mina Almasry wrote:

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 <redacted>
Signed-off-by: Mina Almasry <redacted>

---

...

+
+static bool mp_dmabuf_devmem_release_page(struct page_pool *pool,
+					  struct netmem *netmem)
+{
+	WARN_ON_ONCE(!netmem_is_net_iov(netmem));
+
+	page_pool_clear_pp_info(netmem);
+
+	netdev_free_dmabuf(netmem_to_net_iov(netmem));
+
+	/* We don't want the page pool put_page()ing our net_iovs. */
+	return false;
+}
+
+const struct memory_provider_ops dmabuf_devmem_ops = {
+	.init			= mp_dmabuf_devmem_init,
+	.destroy		= mp_dmabuf_devmem_destroy,
+	.alloc_pages		= mp_dmabuf_devmem_alloc_pages,
+	.release_page		= mp_dmabuf_devmem_release_page,
+};
+EXPORT_SYMBOL(dmabuf_devmem_ops);

It might make sense to move all these functions together with
new code from core/dev.c into a new file

-- 
Pavel Begunkov