When the XDP program attached to a zero-copy AF_XDP socket returns XDP_TX,
queue the umem frame on the XDP TX ring, and arrange for it to be released
via the ZCA free routine, which should place it back onto the reuseq.

Signed-off-by: Jonathan Lemon <jonathan.le...@gmail.com>
---
 drivers/net/ethernet/intel/i40e/i40e_txrx.h |  1 +
 drivers/net/ethernet/intel/i40e/i40e_xsk.c  | 52 +++++++++++++++++++--
 include/net/xdp.h                           | 20 ++++++--
 3 files changed, 65 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h 
b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
index 100e92d2982f..3e7954277737 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
@@ -274,6 +274,7 @@ static inline unsigned int i40e_txd_use_count(unsigned int 
size)
 #define I40E_TX_FLAGS_TSYN             BIT(8)
 #define I40E_TX_FLAGS_FD_SB            BIT(9)
 #define I40E_TX_FLAGS_UDP_TUNNEL       BIT(10)
+#define I40E_TX_FLAGS_ZC_FRAME         BIT(11)
 #define I40E_TX_FLAGS_VLAN_MASK                0xffff0000
 #define I40E_TX_FLAGS_VLAN_PRIO_MASK   0xe0000000
 #define I40E_TX_FLAGS_VLAN_PRIO_SHIFT  29
diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c 
b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index d2e212d007c3..16a31c57906a 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -188,7 +188,6 @@ int i40e_xsk_umem_setup(struct i40e_vsi *vsi, struct 
xdp_umem *umem,
 static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp)
 {
        int err, result = I40E_XDP_PASS;
-       struct i40e_ring *xdp_ring;
        struct bpf_prog *xdp_prog;
        u32 act;
 
@@ -202,9 +201,8 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, 
struct xdp_buff *xdp)
        switch (act) {
        case XDP_PASS:
                break;
-       case XDP_TX:
-               xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
-               result = i40e_xmit_xdp_tx_ring(xdp, xdp_ring);
+       case XDP_TX
+               result = i40e_xmit_rcvd_zc(rx_ring, xdp);
                break;
        case XDP_REDIRECT:
                err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
@@ -623,6 +621,48 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int 
budget)
        return failure ? budget : (int)total_rx_packets;
 }
 
+static int i40e_xmit_rcvd_zc(struct i40e_ring *rx_ring, struct xdp_buff *xdp)
+{
+       struct i40e_ring *xdp_ring;
+       struct i40e_tx_desc *tx_desc;
+       struct i40e_tx_buffer *tx_bi;
+       struct xdp_frame *xdpf;
+       dma_addr_t dma;
+
+       xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
+
+       if (!unlikely(I40E_DESC_UNUSED(xdp_ring))) {
+               xdp_ring->tx_stats.tx_busy++;
+               return I40E_XDP_CONSUMED;
+       }
+       xpdf = convert_to_xdp_frame_keep_zc(xdp);
+       if (unlikely(!xpdf)
+               return I40E_XDP_CONSUMED;
+       xpdf->handle = xdp->handle;
+
+       dma = xdp_umem_get_dma(rx_ring->xsk_umem, xdp->handle);
+       tx_bi = &xdp_ring->tx_bi[xdp_ring->next_to_use];
+       tx_bi->bytecount = xpdf->len;
+       tx_bi->gso_segs = 1;
+       tx_bi->xdpf = xdpf;
+       tx_bi->tx_flags = I40E_TX_FLAGS_ZC_FRAME;
+
+       tx_desc = I40E_TX_DESC(xdp_ring, xdp_ring->next_to_use);
+       tx_desc->buffer_addr = cpu_to_le64(dma);
+       tx_desc->cmd_type_offset_bsz = build_ctob(I40E_TX_DESC_CMD_ICRC |
+                                                 I40E_TX_DESC_CMD_EOP,
+                                                 0, xpdf->len, 0);
+       smp_wmb();
+
+       xdp_ring->next_to_use++;
+       if (xdp_ring->next_to_use == xdp_ring->count)
+               xdp_ring->next_to_use = 0;
+
+       tx_bi->next_to_watch = tx_desc;
+
+       return I40E_XDP_TX;
+}
+
 /**
  * i40e_xmit_zc - Performs zero-copy Tx AF_XDP
  * @xdp_ring: XDP Tx ring
@@ -689,6 +729,10 @@ static void i40e_clean_xdp_tx_buffer(struct i40e_ring 
*tx_ring,
                                     struct i40e_tx_buffer *tx_bi)
 {
        xdp_return_frame(tx_bi->xdpf);
+       if (tx_bi->tx_flags & I40E_TX_FLAGS_ZC_FRAME) {
+               tx_bi->tx_flags = 0;
+               return;
+       }
        dma_unmap_single(tx_ring->dev,
                         dma_unmap_addr(tx_bi, dma),
                         dma_unmap_len(tx_bi, len), DMA_TO_DEVICE);
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 0f25b3675c5c..191359c5ebdd 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -82,6 +82,7 @@ struct xdp_frame {
         */
        struct xdp_mem_info mem;
        struct net_device *dev_rx; /* used by cpumap */
+       unsigned long handle;
 };
 
 /* Clear kernel pointers in xdp_frame */
@@ -95,15 +96,12 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct 
xdp_buff *xdp);
 
 /* Convert xdp_buff to xdp_frame */
 static inline
-struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
+struct xdp_frame *__convert_to_xdp_frame(struct xdp_buff *xdp)
 {
        struct xdp_frame *xdp_frame;
        int metasize;
        int headroom;
 
-       if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
-               return xdp_convert_zc_to_xdp_frame(xdp);
-
        /* Assure headroom is available for storing info */
        headroom = xdp->data - xdp->data_hard_start;
        metasize = xdp->data - xdp->data_meta;
@@ -125,6 +123,20 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff 
*xdp)
        return xdp_frame;
 }
 
+static inline
+struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
+{
+       if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
+               return xdp_convert_zc_to_xdp_frame(xdp);
+       return __convert_to_xdp_frame(xdp);
+}
+
+static inline
+struct xdp_frame *convert_to_xdp_frame_keep_zc(struct xdp_buff *xdp)
+{
+       return __convert_to_xdp_frame(xdp);
+}
+
 void xdp_return_frame(struct xdp_frame *xdpf);
 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
 void xdp_return_buff(struct xdp_buff *xdp);
-- 
2.17.1

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