xsk: Enable sharing of dma mappings

Enable the sharing of dma mappings by moving them out from the buffer
pool. Instead we put each dma mapped umem region in a list in the umem
structure. If dma has already been mapped for this umem and device, it
is not mapped again and the existing dma mappings are reused.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Link: https://lore.kernel.org/bpf/1598603189-32145-9-git-send-email-magnus.karlsson@intel.com

1 files changed, 13 insertions, 0 deletions

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 83f100c6d440..356d0ac74eba 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -28,10 +28,23 @@ struct xdp_buff_xsk {
 	struct list_head free_list_node;
 };
 
+struct xsk_dma_map {
+	dma_addr_t *dma_pages;
+	struct device *dev;
+	struct net_device *netdev;
+	refcount_t users;
+	struct list_head list; /* Protected by the RTNL_LOCK */
+	u32 dma_pages_cnt;
+	bool dma_need_sync;
+};
+
 struct xsk_buff_pool {
 	struct xsk_queue *fq;
 	struct xsk_queue *cq;
 	struct list_head free_list;
+	/* For performance reasons, each buff pool has its own array of dma_pages
+	 * even when they are identical.
+	 */
 	dma_addr_t *dma_pages;
 	struct xdp_buff_xsk *heads;
 	u64 chunk_mask;