[PATCH net v2] net: ti: icssg-prueth: fix XDP_TX from the AF_XDP zero-copy RX path

[David Carlier <devnexen@gmail.com>]

On XDP_TX from the zero-copy RX path, emac_run_xdp() converts the xsk
buffer via xdp_convert_zc_to_xdp_frame(), which clones the data into a
fresh MEM_TYPE_PAGE_ORDER0 page that is not DMA mapped. Transmitting it
as PRUETH_TX_BUFF_TYPE_XDP_TX derives the DMA address with
page_pool_get_dma_addr(), reading an uninitialized page->dma_addr, so
the device DMAs from a bogus address (corrupt TX, or an IOMMU fault).

Pick the TX buffer type from the frame's memory type: keep
PRUETH_TX_BUFF_TYPE_XDP_TX for page_pool frames and use
PRUETH_TX_BUFF_TYPE_XDP_NDO for the cloned zero-copy frame, which is then
DMA mapped through the NDO path and unmapped on completion.

While at it, fix the page_pool XDP_TX completion path. A
PRUETH_TX_BUFF_TYPE_XDP_TX frame carries a page_pool-owned DMA mapping
(established against rx_chn->dma_dev), yet prueth_xmit_free()
unconditionally calls dma_unmap_single() on it with tx_chn->dma_dev,
tearing down a mapping the driver does not own; xdp_return_frame()
already recycles the page back to the pool. Tag such frames with a
dedicated PRUETH_SWDATA_XDPF_TX type so the completion path skips the
unmap, the same way PRUETH_SWDATA_XSK buffers are handled.

Fixes: 7a64bb388df3 ("net: ti: icssg-prueth: Add AF_XDP zero copy for RX")
Fixes: 62aa3246f462 ("net: ti: icssg-prueth: Add XDP support")
Cc: stable@vger.kernel.org
Signed-off-by: David Carlier <devnexen@gmail.com>
---
v2:
 - fold in the page_pool XDP_TX completion-path unmap fix raised by
   Meghana Malladi: tag page_pool TX frames with PRUETH_SWDATA_XDPF_TX
   so prueth_xmit_free() skips dma_unmap_single() on a pool-owned
   mapping; xdp_return_frame() already recycles the page.
 - add Fixes: 62aa3246f462 for that path.
 - no change to the original zero-copy fix.
v1: https://lore.kernel.org/netdev/20260620213756.87499-1-devnexen@gmail.com
 drivers/net/ethernet/ti/icssg/icssg_common.c | 20 +++++++++++++++++---
 drivers/net/ethernet/ti/icssg/icssg_prueth.h |  1 +
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
index 82ddef9c17d5..96c8bf5ef671 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_common.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
@@ -185,7 +185,7 @@ void prueth_xmit_free(struct prueth_tx_chn *tx_chn,
 	first_desc = desc;
 	next_desc = first_desc;
 	swdata = cppi5_hdesc_get_swdata(first_desc);
-	if (swdata->type == PRUETH_SWDATA_XSK)
+	if (swdata->type == PRUETH_SWDATA_XSK || swdata->type == PRUETH_SWDATA_XDPF_TX)
 		goto free_pool;
 
 	cppi5_hdesc_get_obuf(first_desc, &buf_dma, &buf_dma_len);
@@ -259,6 +259,7 @@ int emac_tx_complete_packets(struct prueth_emac *emac, int chn,
 			napi_consume_skb(skb, budget);
 			break;
 		case PRUETH_SWDATA_XDPF:
+		case PRUETH_SWDATA_XDPF_TX:
 			xdpf = swdata->data.xdpf;
 			dev_sw_netstats_tx_add(ndev, 1, xdpf->len);
 			total_bytes += xdpf->len;
@@ -769,7 +770,8 @@ u32 emac_xmit_xdp_frame(struct prueth_emac *emac,
 	k3_udma_glue_tx_dma_to_cppi5_addr(tx_chn->tx_chn, &buf_dma);
 	cppi5_hdesc_attach_buf(first_desc, buf_dma, xdpf->len, buf_dma, xdpf->len);
 	swdata = cppi5_hdesc_get_swdata(first_desc);
-	swdata->type = PRUETH_SWDATA_XDPF;
+	swdata->type = buff_type == PRUETH_TX_BUFF_TYPE_XDP_TX ?
+		PRUETH_SWDATA_XDPF_TX : PRUETH_SWDATA_XDPF;
 	swdata->data.xdpf = xdpf;
 
 	/* Report BQL before sending the packet */
@@ -804,6 +806,7 @@ EXPORT_SYMBOL_GPL(emac_xmit_xdp_frame);
  */
 static u32 emac_run_xdp(struct prueth_emac *emac, struct xdp_buff *xdp, u32 *len)
 {
+	enum prueth_tx_buff_type tx_buff_type;
 	struct net_device *ndev = emac->ndev;
 	struct netdev_queue *netif_txq;
 	int cpu = smp_processor_id();
@@ -826,11 +829,21 @@ static u32 emac_run_xdp(struct prueth_emac *emac, struct xdp_buff *xdp, u32 *len
 			goto drop;
 		}
 
+		/* In AF_XDP zero-copy mode xdp_convert_buff_to_frame()
+		 * clones the xsk buffer into a fresh MEM_TYPE_PAGE_ORDER0
+		 * page that is not DMA mapped. Such a frame must be mapped
+		 * via the NDO path; only a page pool-backed frame already
+		 * carries a usable page_pool DMA address.
+		 */
+		tx_buff_type = xdpf->mem_type == MEM_TYPE_PAGE_POOL ?
+				PRUETH_TX_BUFF_TYPE_XDP_TX :
+				PRUETH_TX_BUFF_TYPE_XDP_NDO;
+
 		q_idx = cpu % emac->tx_ch_num;
 		netif_txq = netdev_get_tx_queue(ndev, q_idx);
 		__netif_tx_lock(netif_txq, cpu);
 		result = emac_xmit_xdp_frame(emac, xdpf, q_idx,
-					     PRUETH_TX_BUFF_TYPE_XDP_TX);
+					     tx_buff_type);
 		__netif_tx_unlock(netif_txq);
 		if (result == ICSSG_XDP_CONSUMED) {
 			ndev->stats.tx_dropped++;
@@ -1395,6 +1408,7 @@ void prueth_tx_cleanup(void *data, dma_addr_t desc_dma)
 		dev_kfree_skb_any(skb);
 		break;
 	case PRUETH_SWDATA_XDPF:
+	case PRUETH_SWDATA_XDPF_TX:
 		xdpf = swdata->data.xdpf;
 		xdp_return_frame(xdpf);
 		break;
diff --git a/drivers/net/ethernet/ti/icssg/icssg_prueth.h b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
index df93d15c5b78..00bb760d68a9 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_prueth.h
+++ b/drivers/net/ethernet/ti/icssg/icssg_prueth.h
@@ -153,6 +153,7 @@ enum prueth_swdata_type {
 	PRUETH_SWDATA_CMD,
 	PRUETH_SWDATA_XDPF,
 	PRUETH_SWDATA_XSK,
+	PRUETH_SWDATA_XDPF_TX,
 };
 
 enum prueth_tx_buff_type {
-- 
2.53.0