[PATCH 1/2] bpf: preserve rx_queue_index across XDP redirects

[Siddharth C <siddharthcibi@icloud.com>]

Store rx_queue_index in struct xdp_frame during xdp_buff to
xdp_frame conversion and restore it when rebuilding xdp_rxq_info
for cpumap and devmap execution paths.

This preserves ingress RX queue information for XDP programs
executed after redirect, allowing access to the original
rx_queue_index instead of losing queue context.

Also propagate rx_queue_index for zero-copy XDP frame conversion.

Signed-off-by: Siddharth_Cibi <siddharthcibi@icloud.com>
---
 include/net/xdp.h   | 2 ++
 kernel/bpf/cpumap.c | 2 +-
 kernel/bpf/devmap.c | 5 ++++-
 net/core/xdp.c      | 1 +
 4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index aa742f413c35..90318b2b76dc 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -301,6 +301,7 @@ struct xdp_frame {
 	 */
 	enum xdp_mem_type mem_type:32;
 	struct net_device *dev_rx; /* used by cpumap */
+	u32 rx_queue_index;
 	u32 frame_sz;
 	u32 flags; /* supported values defined in xdp_buff_flags */
 };
@@ -441,6 +442,7 @@ struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
 
 	/* rxq only valid until napi_schedule ends, convert to xdp_mem_type */
 	xdp_frame->mem_type = xdp->rxq->mem.type;
+	xdp_frame->rx_queue_index = xdp->rxq->queue_index;
 
 	return xdp_frame;
 }
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 5e59ab896f05..8f2d7013620f 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -197,7 +197,7 @@ static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
 
 		rxq.dev = xdpf->dev_rx;
 		rxq.mem.type = xdpf->mem_type;
-		/* TODO: report queue_index to xdp_rxq_info */
+		rxq.queue_index = xdpf->rx_queue_index;
 
 		xdp_convert_frame_to_buff(xdpf, &xdp);
 
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index dc7b859e8bbf..f419fa0e53e5 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -339,7 +339,7 @@ static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
 				struct net_device *rx_dev)
 {
 	struct xdp_txq_info txq = { .dev = tx_dev };
-	struct xdp_rxq_info rxq = { .dev = rx_dev };
+	struct xdp_rxq_info rxq = { };
 	struct xdp_buff xdp;
 	int i, nframes = 0;
 
@@ -349,6 +349,9 @@ static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
 		int err;
 
 		xdp_convert_frame_to_buff(xdpf, &xdp);
+		rxq.dev = rx_dev;
+		rxq.mem.type = xdpf->mem_type;
+		rxq.queue_index = xdpf->rx_queue_index;
 		xdp.txq = &txq;
 		xdp.rxq = &rxq;
 
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 9890a30584ba..9691d8dfadf3 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -606,6 +606,7 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
 	xdpf->metasize = metasize;
 	xdpf->frame_sz = PAGE_SIZE;
 	xdpf->mem_type = MEM_TYPE_PAGE_ORDER0;
+	xdpf->rx_queue_index = xdp->rxq->queue_index;
 
 	xsk_buff_free(xdp);
 	return xdpf;
-- 
2.53.0