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

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 907537d..0140d08 100644 (file)
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -81,6 +81,8 @@ struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
                                                struct xdp_umem *umem);
 int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
                  u16 queue_id, u16 flags);
+int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
+                        struct net_device *dev, u16 queue_id);
 void xp_destroy(struct xsk_buff_pool *pool);
 void xp_release(struct xdp_buff_xsk *xskb);
 void xp_get_pool(struct xsk_buff_pool *pool);

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 067e854..ea8d2ec 100644 (file)
--- 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;

diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index 547eb41..795d7c8 100644 (file)
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -123,8 +123,8 @@ static void xp_disable_drv_zc(struct xsk_buff_pool *pool)
        }
 }
 
-int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev,
-                 u16 queue_id, u16 flags)
+static int __xp_assign_dev(struct xsk_buff_pool *pool,
+                          struct net_device *netdev, u16 queue_id, u16 flags)
 {
        bool force_zc, force_copy;
        struct netdev_bpf bpf;
@@ -193,6 +193,28 @@ err_unreg_pool:
        return err;
 }
 
+int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *dev,
+                 u16 queue_id, u16 flags)
+{
+       return __xp_assign_dev(pool, dev, queue_id, flags);
+}
+
+int xp_assign_dev_shared(struct xsk_buff_pool *pool, struct xdp_umem *umem,
+                        struct net_device *dev, u16 queue_id)
+{
+       u16 flags;
+
+       /* One fill and completion ring required for each queue id. */
+       if (!pool->fq || !pool->cq)
+               return -EINVAL;
+
+       flags = umem->zc ? XDP_ZEROCOPY : XDP_COPY;
+       if (pool->uses_need_wakeup)
+               flags |= XDP_USE_NEED_WAKEUP;
+
+       return __xp_assign_dev(pool, dev, queue_id, flags);
+}
+
 void xp_clear_dev(struct xsk_buff_pool *pool)
 {
        if (!pool->netdev)