[PATCH v1 07/15] net: page pool: add helper creating area from pages

[David Wei <dw@xxxxxxxxxxx>]

From: Pavel Begunkov <asml.silence@xxxxxxxxx>

Add a helper that takes an array of pages and initialises passed in
memory provider's area with them, where each net_iov takes one page.
It's also responsible for setting up dma mappings.

We keep it in page_pool.c not to leak netmem details to outside
providers like io_uring, which don't have access to netmem_priv.h
and other private helpers.

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: David Wei <dw@xxxxxxxxxxx>
---
 include/net/page_pool/types.h | 17 ++++++++++
 net/core/page_pool.c          | 61 +++++++++++++++++++++++++++++++++--
 2 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index fd0376ad0d26..1180ad07423c 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -271,6 +271,11 @@ void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
 			   const struct xdp_mem_info *mem);
 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 			     int count);
+
+int page_pool_init_paged_area(struct page_pool *pool,
+			      struct net_iov_area *area, struct page **pages);
+void page_pool_release_area(struct page_pool *pool,
+			    struct net_iov_area *area);
 #else
 static inline void page_pool_destroy(struct page_pool *pool)
 {
@@ -286,6 +291,18 @@ static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 					   int count)
 {
 }
+
+static inline int page_pool_init_paged_area(struct page_pool *pool,
+					    struct net_iov_area *area,
+					    struct page **pages)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void page_pool_release_area(struct page_pool *pool,
+					  struct net_iov_area *area)
+{
+}
 #endif
 
 void page_pool_put_unrefed_netmem(struct page_pool *pool, netmem_ref netmem,
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 9a675e16e6a4..112b6fe4b7ff 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -459,7 +459,8 @@ page_pool_dma_sync_for_device(const struct page_pool *pool,
 		__page_pool_dma_sync_for_device(pool, netmem, dma_sync_size);
 }
 
-static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem)
+static bool page_pool_dma_map_page(struct page_pool *pool, netmem_ref netmem,
+				   struct page *page)
 {
 	dma_addr_t dma;
 
@@ -468,7 +469,7 @@ static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem)
 	 * into page private data (i.e 32bit cpu with 64bit DMA caps)
 	 * This mapping is kept for lifetime of page, until leaving pool.
 	 */
-	dma = dma_map_page_attrs(pool->p.dev, netmem_to_page(netmem), 0,
+	dma = dma_map_page_attrs(pool->p.dev, page, 0,
 				 (PAGE_SIZE << pool->p.order), pool->p.dma_dir,
 				 DMA_ATTR_SKIP_CPU_SYNC |
 					 DMA_ATTR_WEAK_ORDERING);
@@ -490,6 +491,11 @@ static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem)
 	return false;
 }
 
+static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem)
+{
+	return page_pool_dma_map_page(pool, netmem, netmem_to_page(netmem));
+}
+
 static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
 						 gfp_t gfp)
 {
@@ -1154,3 +1160,54 @@ void page_pool_update_nid(struct page_pool *pool, int new_nid)
 	}
 }
 EXPORT_SYMBOL(page_pool_update_nid);
+
+static void page_pool_release_page_dma(struct page_pool *pool,
+				       netmem_ref netmem)
+{
+	__page_pool_release_page_dma(pool, netmem);
+}
+
+int page_pool_init_paged_area(struct page_pool *pool,
+			      struct net_iov_area *area, struct page **pages)
+{
+	struct net_iov *niov;
+	netmem_ref netmem;
+	int i, ret = 0;
+
+	if (!pool->dma_map)
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < area->num_niovs; i++) {
+		niov = &area->niovs[i];
+		netmem = net_iov_to_netmem(niov);
+
+		page_pool_set_pp_info(pool, netmem);
+		if (!page_pool_dma_map_page(pool, netmem, pages[i])) {
+			ret = -EINVAL;
+			goto err_unmap_dma;
+		}
+	}
+	return 0;
+
+err_unmap_dma:
+	while (i--) {
+		netmem = net_iov_to_netmem(&area->niovs[i]);
+		page_pool_release_page_dma(pool, netmem);
+	}
+	return ret;
+}
+
+void page_pool_release_area(struct page_pool *pool,
+			    struct net_iov_area *area)
+{
+	int i;
+
+	if (!pool->dma_map)
+		return;
+
+	for (i = 0; i < area->num_niovs; i++) {
+		struct net_iov *niov = &area->niovs[i];
+
+		page_pool_release_page_dma(pool, net_iov_to_netmem(niov));
+	}
+}
-- 
2.43.5