[PATCH net-next 2/3] xsk: honor XDP_TX_METADATA in zero-copy path

[Stanislav Fomichev <sdf.kernel@gmail.com>]

The zero-copy path reads TX metadata whenever the UMEM has metadata space,
even if the descriptor does not set XDP_TX_METADATA. Pass descriptor
options through the metadata helpers and ignore metadata unless the option
is set.

This does not change the existing per-WQE metadata handling for mlx5
MPWQEs, where the descriptor that starts a session configures offload state
shared by the batch. Supporting mixed metadata states within one MPWQE
requires a separate fix.

Fixes: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
 drivers/net/ethernet/intel/igc/igc_main.c     |  3 ++-
 .../ethernet/mellanox/mlx5/core/en/xsk/tx.c   |  2 +-
 .../net/ethernet/stmicro/stmmac/stmmac_main.c |  3 ++-
 include/net/libeth/xsk.h                      |  2 +-
 include/net/xdp_sock_drv.h                    | 22 +++++++++++--------
 include/net/xsk_buff_pool.h                   |  3 ++-
 net/xdp/xsk_buff_pool.c                       |  7 ++++--
 7 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 8b9ce7cbfff9..1fb5f3cbe93c 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -3071,7 +3071,8 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring)
 		olinfo_status = xdp_desc.len << IGC_ADVTXD_PAYLEN_SHIFT;
 
 		dma = xsk_buff_raw_get_dma(pool, xdp_desc.addr);
-		meta = xsk_buff_get_metadata(pool, xdp_desc.addr);
+		meta = xsk_buff_get_metadata(pool, xdp_desc.addr,
+					     xdp_desc.options);
 		xsk_buff_raw_dma_sync_for_device(pool, dma, xdp_desc.len);
 		bi = &ring->tx_buffer_info[ntu];
 
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c
index 3d19dad8f868..d194eeddd7b5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c
@@ -99,7 +99,7 @@ bool mlx5e_xsk_tx(struct mlx5e_xdpsq *sq, unsigned int budget)
 		xdptxd.dma_addr = xsk_buff_raw_get_dma(pool, desc.addr);
 		xdptxd.data = xsk_buff_raw_get_data(pool, desc.addr);
 		xdptxd.len = desc.len;
-		meta = xsk_buff_get_metadata(pool, desc.addr);
+		meta = xsk_buff_get_metadata(pool, desc.addr, desc.options);
 
 		xsk_buff_raw_dma_sync_for_device(pool, xdptxd.dma_addr, xdptxd.len);
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b2b7d0242dd3..efa35cfecc4f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2723,7 +2723,8 @@ static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
 
 		tx_desc = stmmac_get_tx_desc(priv, tx_q, entry);
 		dma_addr = xsk_buff_raw_get_dma(pool, xdp_desc.addr);
-		meta = xsk_buff_get_metadata(pool, xdp_desc.addr);
+		meta = xsk_buff_get_metadata(pool, xdp_desc.addr,
+					     xdp_desc.options);
 		xsk_buff_raw_dma_sync_for_device(pool, dma_addr, xdp_desc.len);
 
 		/* To return XDP buffer to XSK pool, we simple call
diff --git a/include/net/libeth/xsk.h b/include/net/libeth/xsk.h
index 5dcc0d7f65b7..a452b7828ce4 100644
--- a/include/net/libeth/xsk.h
+++ b/include/net/libeth/xsk.h
@@ -196,7 +196,7 @@ __libeth_xsk_xmit_fill_buf_md(const struct xdp_desc *xdesc,
 	struct libeth_xdp_tx_desc desc;
 	struct xdp_desc_ctx ctx;
 
-	ctx = xsk_buff_raw_get_ctx(sq->pool, xdesc->addr);
+	ctx = xsk_buff_raw_get_ctx(sq->pool, xdesc->addr, xdesc->options);
 	desc = (typeof(desc)){
 		.addr	= ctx.dma,
 		__libeth_xdp_tx_len(xdesc->len),
diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
index b344789f5df8..d94aeb506379 100644
--- a/include/net/xdp_sock_drv.h
+++ b/include/net/xdp_sock_drv.h
@@ -240,6 +240,7 @@ static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
  * xsk_buff_raw_get_ctx - get &xdp_desc context
  * @pool: XSk buff pool desc address belongs to
  * @addr: desc address (from userspace)
+ * @options: desc options (from userspace)
  *
  * Wrapper for xp_raw_get_ctx() to be used in drivers, see its kdoc for
  * details.
@@ -248,9 +249,9 @@ static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
  * pointer, if it is present (initialized to %NULL otherwise).
  */
 static inline struct xdp_desc_ctx
-xsk_buff_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr)
+xsk_buff_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr, u32 options)
 {
-	return xp_raw_get_ctx(pool, addr);
+	return xp_raw_get_ctx(pool, addr, options);
 }
 
 #define XDP_TXMD_FLAGS_VALID ( \
@@ -318,18 +319,20 @@ xsk_tx_metadata_request(const struct xsk_buff_pool *pool,
 }
 
 static inline struct xsk_tx_metadata *
-__xsk_buff_get_metadata(const struct xsk_buff_pool *pool, void *data)
+__xsk_buff_get_metadata(const struct xsk_buff_pool *pool, void *data,
+			unsigned int options)
 {
-	if (!pool->tx_metadata_len)
+	if (!pool->tx_metadata_len || !(options & XDP_TX_METADATA))
 		return NULL;
 
 	return data - pool->tx_metadata_len;
 }
 
 static inline struct xsk_tx_metadata *
-xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr)
+xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr, u32 options)
 {
-	return __xsk_buff_get_metadata(pool, xp_raw_get_data(pool, addr));
+	return __xsk_buff_get_metadata(pool, xp_raw_get_data(pool, addr),
+				       options);
 }
 
 static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp)
@@ -510,7 +513,7 @@ static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
 }
 
 static inline struct xdp_desc_ctx
-xsk_buff_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr)
+xsk_buff_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr, u32 options)
 {
 	return (struct xdp_desc_ctx){ };
 }
@@ -530,13 +533,14 @@ xsk_tx_metadata_request(const struct xsk_buff_pool *pool,
 }
 
 static inline struct xsk_tx_metadata *
-__xsk_buff_get_metadata(const struct xsk_buff_pool *pool, void *data)
+__xsk_buff_get_metadata(const struct xsk_buff_pool *pool, void *data,
+			unsigned int options)
 {
 	return NULL;
 }
 
 static inline struct xsk_tx_metadata *
-xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr)
+xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr, u32 options)
 {
 	return NULL;
 }
diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 2bb1d122b1bc..a7df573784fd 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -154,7 +154,8 @@ struct xdp_desc_ctx {
 	struct xsk_tx_metadata *meta;
 };
 
-struct xdp_desc_ctx xp_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr);
+struct xdp_desc_ctx xp_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr,
+				   u32 options);
 
 static inline dma_addr_t xp_get_dma(struct xdp_buff_xsk *xskb)
 {
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index 78c14f106395..9d2d94f1fb75 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -763,6 +763,7 @@ EXPORT_SYMBOL(xp_raw_get_dma);
  * xp_raw_get_ctx - get &xdp_desc context
  * @pool: XSk buff pool desc address belongs to
  * @addr: desc address (from userspace)
+ * @options: desc options (from userspace)
  *
  * Helper for getting desc's DMA address and metadata pointer, if present.
  * Saves one call on hotpath and double calculation of the actual address.
@@ -771,14 +772,16 @@ EXPORT_SYMBOL(xp_raw_get_dma);
  * Return: new &xdp_desc_ctx struct containing desc's DMA address and metadata
  * pointer, if it is present (initialized to %NULL otherwise).
  */
-struct xdp_desc_ctx xp_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr)
+struct xdp_desc_ctx xp_raw_get_ctx(const struct xsk_buff_pool *pool, u64 addr,
+				   u32 options)
 {
 	struct xdp_desc_ctx ret;
 
 	addr = __xp_raw_get_addr(pool, addr);
 
 	ret.dma = __xp_raw_get_dma(pool, addr);
-	ret.meta = __xsk_buff_get_metadata(pool, __xp_raw_get_data(pool, addr));
+	ret.meta = __xsk_buff_get_metadata(pool, __xp_raw_get_data(pool, addr),
+					   options);
 
 	return ret;
 }
-- 
2.53.0-Meta