xsk: Add shared umem support between queue ids

Add support to share a umem between queue ids on the same
device. This mode can be invoked with the XDP_SHARED_UMEM bind
flag. Previously, sharing was only supported within the same
queue id and device, and you shared one set of fill and
completion rings. However, note that when sharing a umem between
queue ids, you need to create a fill ring and a completion ring
and tie them to the socket before you do the bind with the
XDP_SHARED_UMEM flag. This so that the single-producer
single-consumer semantics can be upheld.

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/1598603189-32145-12-git-send-email-magnus.karlsson@intel.com

1 files changed, 30 insertions, 14 deletions

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 067e85424d36..ea8d2ec8386e 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -689,12 +689,6 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 			goto out_unlock;
 		}
 
-		if (xs->fq_tmp || xs->cq_tmp) {
-			/* Do not allow setting your own fq or cq. */
-			err = -EINVAL;
-			goto out_unlock;
-		}
-
 		sock = xsk_lookup_xsk_from_fd(sxdp->sxdp_shared_umem_fd);
 		if (IS_ERR(sock)) {
 			err = PTR_ERR(sock);
@@ -707,15 +701,41 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 			sockfd_put(sock);
 			goto out_unlock;
 		}
-		if (umem_xs->dev != dev || umem_xs->queue_id != qid) {
+		if (umem_xs->dev != dev) {
 			err = -EINVAL;
 			sockfd_put(sock);
 			goto out_unlock;
 		}
 
-		/* Share the buffer pool with the other socket. */
-		xp_get_pool(umem_xs->pool);
-		xs->pool = umem_xs->pool;
+		if (umem_xs->queue_id != qid) {
+			/* Share the umem with another socket on another qid */
+			xs->pool = xp_create_and_assign_umem(xs,
+							     umem_xs->umem);
+			if (!xs->pool) {
+				sockfd_put(sock);
+				goto out_unlock;
+			}
+
+			err = xp_assign_dev_shared(xs->pool, umem_xs->umem,
+						   dev, qid);
+			if (err) {
+				xp_destroy(xs->pool);
+				sockfd_put(sock);
+				goto out_unlock;
+			}
+		} else {
+			/* Share the buffer pool with the other socket. */
+			if (xs->fq_tmp || xs->cq_tmp) {
+				/* Do not allow setting your own fq or cq. */
+				err = -EINVAL;
+				sockfd_put(sock);
+				goto out_unlock;
+			}
+
+			xp_get_pool(umem_xs->pool);
+			xs->pool = umem_xs->pool;
+		}
+
 		xdp_get_umem(umem_xs->umem);
 		WRITE_ONCE(xs->umem, umem_xs->umem);
 		sockfd_put(sock);
@@ -847,10 +867,6 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
 			mutex_unlock(&xs->mutex);
 			return -EBUSY;
 		}
-		if (!xs->umem) {
-			mutex_unlock(&xs->mutex);
-			return -EINVAL;
-		}
 
 		q = (optname == XDP_UMEM_FILL_RING) ? &xs->fq_tmp :
 			&xs->cq_tmp;