[PATCH v9 net-next 0/4] add multi-buff support for xdp running in generic mode

[PATCH v9 net-next 0/4] add multi-buff support for xdp running in generic mode

[Lorenzo Bianconi]

Introduce multi-buffer support for xdp running in generic mode not always
linearizing the skb in netif_receive_generic_xdp routine.
Introduce generic percpu page_pools allocator.

Changes since v8:
- fix veth regression introduce in veth.sh selftest
Changes since v7:
- fix sparse warnings
Changes since v6:
- remove patch 4/5 'net: page_pool: make stats available just for global pools'
- rename netif_skb_segment_for_xdp() in
  skb_cow_data_for_xdp()/skb_pp_cow_data()
- rename net_page_pool_alloc() in net_page_pool_create()
- rename page_pool percpu pointer in system_page_pool
- set percpu page_pool memory size
Changes since v5:
- move percpu page_pool pointer out of softnet_data in a dedicated variable
- make page_pool stats available just for global pools
- rely on netif_skb_segment_for_xdp utility routine in veth driver
Changes since v4:
- fix compilation error if page_pools are not enabled
Changes since v3:
- introduce page_pool in softnet_data structure
- rely on page_pools for xdp_generic code
Changes since v2:
- rely on napi_alloc_frag() and napi_build_skb() to build the new skb
Changes since v1:
- explicitly keep the skb segmented in netif_skb_check_for_generic_xdp() and
  do not rely on pskb_expand_head()

Lorenzo Bianconi (4):
  net: add generic percpu page_pool allocator
  xdp: rely on skb pointer reference in do_xdp_generic and
    netif_receive_generic_xdp
  xdp: add multi-buff support for xdp running in generic mode
  veth: rely on skb_pp_cow_data utility routine

 drivers/net/tun.c             |   4 +-
 drivers/net/veth.c            |  74 +------------------
 include/linux/netdevice.h     |   2 +-
 include/linux/skbuff.h        |   4 ++
 include/net/page_pool/types.h |   3 +
 net/core/dev.c                | 131 +++++++++++++++++++++++++++-------
 net/core/page_pool.c          |  23 ++++--
 net/core/skbuff.c             |  97 ++++++++++++++++++++++++-
 8 files changed, 231 insertions(+), 107 deletions(-)

-- 
2.43.0

[PATCH v9 net-next 1/4] net: add generic percpu page_pool allocator

[Lorenzo Bianconi]

Introduce generic percpu page_pools allocator.
Moreover add page_pool_create_percpu() and cpuid filed in page_pool struct
in order to recycle the page in the page_pool "hot" cache if
napi_pp_put_page() is running on the same cpu.
This is a preliminary patch to add xdp multi-buff support for xdp running
in generic mode.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 include/net/page_pool/types.h |  3 +++
 net/core/dev.c                | 45 +++++++++++++++++++++++++++++++++++
 net/core/page_pool.c          | 23 ++++++++++++++----
 net/core/skbuff.c             |  5 ++--
 4 files changed, 70 insertions(+), 6 deletions(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 76481c465375..3828396ae60c 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -128,6 +128,7 @@ struct page_pool_stats {
 struct page_pool {
 	struct page_pool_params_fast p;
 
+	int cpuid;
 	bool has_init_callback;
 
 	long frag_users;
@@ -203,6 +204,8 @@ struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
 struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
 				  unsigned int size, gfp_t gfp);
 struct page_pool *page_pool_create(const struct page_pool_params *params);
+struct page_pool *page_pool_create_percpu(const struct page_pool_params *params,
+					  int cpuid);
 
 struct xdp_mem_info;
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 31f2c97d1990..e403cb44b26b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -153,6 +153,8 @@
 #include <linux/prandom.h>
 #include <linux/once_lite.h>
 #include <net/netdev_rx_queue.h>
+#include <net/page_pool/types.h>
+#include <net/page_pool/helpers.h>
 
 #include "dev.h"
 #include "net-sysfs.h"
@@ -450,6 +452,12 @@ static RAW_NOTIFIER_HEAD(netdev_chain);
 DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
 EXPORT_PER_CPU_SYMBOL(softnet_data);
 
+/* Page_pool has a lockless array/stack to alloc/recycle pages.
+ * PP consumers must pay attention to run APIs in the appropriate context
+ * (e.g. NAPI context).
+ */
+static DEFINE_PER_CPU_ALIGNED(struct page_pool *, system_page_pool);
+
 #ifdef CONFIG_LOCKDEP
 /*
  * register_netdevice() inits txq->_xmit_lock and sets lockdep class
@@ -11724,6 +11732,27 @@ static void __init net_dev_struct_check(void)
  *
  */
 
+/* We allocate 256 pages for each CPU if PAGE_SHIFT is 12 */
+#define SYSTEM_PERCPU_PAGE_POOL_SIZE	((1 << 20) / PAGE_SIZE)
+
+static int net_page_pool_create(int cpuid)
+{
+#if IS_ENABLED(CONFIG_PAGE_POOL)
+	struct page_pool_params page_pool_params = {
+		.pool_size = SYSTEM_PERCPU_PAGE_POOL_SIZE,
+		.nid = NUMA_NO_NODE,
+	};
+	struct page_pool *pp_ptr;
+
+	pp_ptr = page_pool_create_percpu(&page_pool_params, cpuid);
+	if (IS_ERR(pp_ptr))
+		return -ENOMEM;
+
+	per_cpu(system_page_pool, cpuid) = pp_ptr;
+#endif
+	return 0;
+}
+
 /*
  *       This is called single threaded during boot, so no need
  *       to take the rtnl semaphore.
@@ -11776,6 +11805,9 @@ static int __init net_dev_init(void)
 		init_gro_hash(&sd->backlog);
 		sd->backlog.poll = process_backlog;
 		sd->backlog.weight = weight_p;
+
+		if (net_page_pool_create(i))
+			goto out;
 	}
 
 	dev_boot_phase = 0;
@@ -11803,6 +11835,19 @@ static int __init net_dev_init(void)
 	WARN_ON(rc < 0);
 	rc = 0;
 out:
+	if (rc < 0) {
+		for_each_possible_cpu(i) {
+			struct page_pool *pp_ptr;
+
+			pp_ptr = per_cpu(system_page_pool, i);
+			if (!pp_ptr)
+				continue;
+
+			page_pool_destroy(pp_ptr);
+			per_cpu(system_page_pool, i) = NULL;
+		}
+	}
+
 	return rc;
 }
 
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 4933762e5a6b..89c835fcf094 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -171,13 +171,16 @@ static void page_pool_producer_unlock(struct page_pool *pool,
 }
 
 static int page_pool_init(struct page_pool *pool,
-			  const struct page_pool_params *params)
+			  const struct page_pool_params *params,
+			  int cpuid)
 {
 	unsigned int ring_qsize = 1024; /* Default */
 
 	memcpy(&pool->p, &params->fast, sizeof(pool->p));
 	memcpy(&pool->slow, &params->slow, sizeof(pool->slow));
 
+	pool->cpuid = cpuid;
+
 	/* Validate only known flags were used */
 	if (pool->p.flags & ~(PP_FLAG_ALL))
 		return -EINVAL;
@@ -253,10 +256,12 @@ static void page_pool_uninit(struct page_pool *pool)
 }
 
 /**
- * page_pool_create() - create a page pool.
+ * page_pool_create_percpu() - create a page pool for a given cpu.
  * @params: parameters, see struct page_pool_params
+ * @cpuid: cpu identifier
  */
-struct page_pool *page_pool_create(const struct page_pool_params *params)
+struct page_pool *
+page_pool_create_percpu(const struct page_pool_params *params, int cpuid)
 {
 	struct page_pool *pool;
 	int err;
@@ -265,7 +270,7 @@ struct page_pool *page_pool_create(const struct page_pool_params *params)
 	if (!pool)
 		return ERR_PTR(-ENOMEM);
 
-	err = page_pool_init(pool, params);
+	err = page_pool_init(pool, params, cpuid);
 	if (err < 0)
 		goto err_free;
 
@@ -282,6 +287,16 @@ struct page_pool *page_pool_create(const struct page_pool_params *params)
 	kfree(pool);
 	return ERR_PTR(err);
 }
+EXPORT_SYMBOL(page_pool_create_percpu);
+
+/**
+ * page_pool_create() - create a page pool
+ * @params: parameters, see struct page_pool_params
+ */
+struct page_pool *page_pool_create(const struct page_pool_params *params)
+{
+	return page_pool_create_percpu(params, -1);
+}
 EXPORT_SYMBOL(page_pool_create);
 
 static void page_pool_return_page(struct page_pool *pool, struct page *page);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index edbbef563d4d..9e5eb47b4025 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -923,9 +923,10 @@ bool napi_pp_put_page(struct page *page, bool napi_safe)
 	 */
 	if (napi_safe || in_softirq()) {
 		const struct napi_struct *napi = READ_ONCE(pp->p.napi);
+		unsigned int cpuid = smp_processor_id();
 
-		allow_direct = napi &&
-			READ_ONCE(napi->list_owner) == smp_processor_id();
+		allow_direct = napi && READ_ONCE(napi->list_owner) == cpuid;
+		allow_direct |= (pp->cpuid == cpuid);
 	}
 
 	/* Driver set this to memory recycling info. Reset it on recycle.
-- 
2.43.0

[PATCH v9 net-next 2/4] xdp: rely on skb pointer reference in do_xdp_generic and netif_receive_generic_xdp

[Lorenzo Bianconi]

Rely on skb pointer reference instead of the skb pointer in do_xdp_generic
and netif_receive_generic_xdp routine signatures.
This is a preliminary patch to add multi-buff support for xdp running in
generic mode where we will need to reallocate the skb to avoid
linearization and we will need to make it visible to do_xdp_generic()
caller.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/tun.c         |  4 ++--
 include/linux/netdevice.h |  2 +-
 net/core/dev.c            | 16 +++++++++-------
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index b472f2c972d8..bc80fc1d576e 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1926,7 +1926,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		rcu_read_lock();
 		xdp_prog = rcu_dereference(tun->xdp_prog);
 		if (xdp_prog) {
-			ret = do_xdp_generic(xdp_prog, skb);
+			ret = do_xdp_generic(xdp_prog, &skb);
 			if (ret != XDP_PASS) {
 				rcu_read_unlock();
 				local_bh_enable();
@@ -2516,7 +2516,7 @@ static int tun_xdp_one(struct tun_struct *tun,
 	skb_record_rx_queue(skb, tfile->queue_index);
 
 	if (skb_xdp) {
-		ret = do_xdp_generic(xdp_prog, skb);
+		ret = do_xdp_generic(xdp_prog, &skb);
 		if (ret != XDP_PASS) {
 			ret = 0;
 			goto out;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 07cefa32eafa..a3f9c95da51e 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3958,7 +3958,7 @@ static inline void dev_consume_skb_any(struct sk_buff *skb)
 u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 			     struct bpf_prog *xdp_prog);
 void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog);
-int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb);
+int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff **pskb);
 int netif_rx(struct sk_buff *skb);
 int __netif_rx(struct sk_buff *skb);
 
diff --git a/net/core/dev.c b/net/core/dev.c
index e403cb44b26b..1482c3058fc2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4936,10 +4936,11 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 	return act;
 }
 
-static u32 netif_receive_generic_xdp(struct sk_buff *skb,
+static u32 netif_receive_generic_xdp(struct sk_buff **pskb,
 				     struct xdp_buff *xdp,
 				     struct bpf_prog *xdp_prog)
 {
+	struct sk_buff *skb = *pskb;
 	u32 act = XDP_DROP;
 
 	/* Reinjected packets coming from act_mirred or similar should
@@ -5020,24 +5021,24 @@ void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
 
 static DEFINE_STATIC_KEY_FALSE(generic_xdp_needed_key);
 
-int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
+int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff **pskb)
 {
 	if (xdp_prog) {
 		struct xdp_buff xdp;
 		u32 act;
 		int err;
 
-		act = netif_receive_generic_xdp(skb, &xdp, xdp_prog);
+		act = netif_receive_generic_xdp(pskb, &xdp, xdp_prog);
 		if (act != XDP_PASS) {
 			switch (act) {
 			case XDP_REDIRECT:
-				err = xdp_do_generic_redirect(skb->dev, skb,
+				err = xdp_do_generic_redirect((*pskb)->dev, *pskb,
 							      &xdp, xdp_prog);
 				if (err)
 					goto out_redir;
 				break;
 			case XDP_TX:
-				generic_xdp_tx(skb, xdp_prog);
+				generic_xdp_tx(*pskb, xdp_prog);
 				break;
 			}
 			return XDP_DROP;
@@ -5045,7 +5046,7 @@ int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
 	}
 	return XDP_PASS;
 out_redir:
-	kfree_skb_reason(skb, SKB_DROP_REASON_XDP);
+	kfree_skb_reason(*pskb, SKB_DROP_REASON_XDP);
 	return XDP_DROP;
 }
 EXPORT_SYMBOL_GPL(do_xdp_generic);
@@ -5368,7 +5369,8 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
 		int ret2;
 
 		migrate_disable();
-		ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog), skb);
+		ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog),
+				      &skb);
 		migrate_enable();
 
 		if (ret2 != XDP_PASS) {
-- 
2.43.0

[PATCH v9 net-next 3/4] xdp: add multi-buff support for xdp running in generic mode

[Lorenzo Bianconi]

Similar to native xdp, do not always linearize the skb in
netif_receive_generic_xdp routine but create a non-linear xdp_buff to be
processed by the eBPF program. This allow to add multi-buffer support
for xdp running in generic mode.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 include/linux/skbuff.h |  2 +
 net/core/dev.c         | 70 +++++++++++++++++++++++---------
 net/core/skbuff.c      | 91 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 144 insertions(+), 19 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2dde34c29203..def3d8689c3d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3446,6 +3446,8 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
 	__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
 }
 
+int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
+			 struct bpf_prog *prog);
 bool napi_pp_put_page(struct page *page, bool napi_safe);
 
 static inline void
diff --git a/net/core/dev.c b/net/core/dev.c
index 1482c3058fc2..97de7700d3cb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4874,6 +4874,12 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 	xdp_init_buff(xdp, frame_sz, &rxqueue->xdp_rxq);
 	xdp_prepare_buff(xdp, hard_start, skb_headroom(skb) - mac_len,
 			 skb_headlen(skb) + mac_len, true);
+	if (skb_is_nonlinear(skb)) {
+		skb_shinfo(skb)->xdp_frags_size = skb->data_len;
+		xdp_buff_set_frags_flag(xdp);
+	} else {
+		xdp_buff_clear_frags_flag(xdp);
+	}
 
 	orig_data_end = xdp->data_end;
 	orig_data = xdp->data;
@@ -4903,6 +4909,14 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 		skb->len += off; /* positive on grow, negative on shrink */
 	}
 
+	/* XDP frag metadata (e.g. nr_frags) are updated in eBPF helpers
+	 * (e.g. bpf_xdp_adjust_tail), we need to update data_len here.
+	 */
+	if (xdp_buff_has_frags(xdp))
+		skb->data_len = skb_shinfo(skb)->xdp_frags_size;
+	else
+		skb->data_len = 0;
+
 	/* check if XDP changed eth hdr such SKB needs update */
 	eth = (struct ethhdr *)xdp->data;
 	if ((orig_eth_type != eth->h_proto) ||
@@ -4936,12 +4950,35 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 	return act;
 }
 
+static int
+netif_skb_check_for_xdp(struct sk_buff **pskb, struct bpf_prog *prog)
+{
+	struct sk_buff *skb = *pskb;
+	int err, hroom, troom;
+
+	if (!skb_cow_data_for_xdp(this_cpu_read(system_page_pool), pskb, prog))
+		return 0;
+
+	/* In case we have to go down the path and also linearize,
+	 * then lets do the pskb_expand_head() work just once here.
+	 */
+	hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
+	troom = skb->tail + skb->data_len - skb->end;
+	err = pskb_expand_head(skb,
+			       hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
+			       troom > 0 ? troom + 128 : 0, GFP_ATOMIC);
+	if (err)
+		return err;
+
+	return skb_linearize(skb);
+}
+
 static u32 netif_receive_generic_xdp(struct sk_buff **pskb,
 				     struct xdp_buff *xdp,
 				     struct bpf_prog *xdp_prog)
 {
 	struct sk_buff *skb = *pskb;
-	u32 act = XDP_DROP;
+	u32 mac_len, act = XDP_DROP;
 
 	/* Reinjected packets coming from act_mirred or similar should
 	 * not get XDP generic processing.
@@ -4949,41 +4986,36 @@ static u32 netif_receive_generic_xdp(struct sk_buff **pskb,
 	if (skb_is_redirected(skb))
 		return XDP_PASS;
 
-	/* XDP packets must be linear and must have sufficient headroom
-	 * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also
-	 * native XDP provides, thus we need to do it here as well.
+	/* XDP packets must have sufficient headroom of XDP_PACKET_HEADROOM
+	 * bytes. This is the guarantee that also native XDP provides,
+	 * thus we need to do it here as well.
 	 */
+	mac_len = skb->data - skb_mac_header(skb);
+	__skb_push(skb, mac_len);
+
 	if (skb_cloned(skb) || skb_is_nonlinear(skb) ||
 	    skb_headroom(skb) < XDP_PACKET_HEADROOM) {
-		int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb);
-		int troom = skb->tail + skb->data_len - skb->end;
-
-		/* In case we have to go down the path and also linearize,
-		 * then lets do the pskb_expand_head() work just once here.
-		 */
-		if (pskb_expand_head(skb,
-				     hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
-				     troom > 0 ? troom + 128 : 0, GFP_ATOMIC))
-			goto do_drop;
-		if (skb_linearize(skb))
+		if (netif_skb_check_for_xdp(pskb, xdp_prog))
 			goto do_drop;
 	}
 
-	act = bpf_prog_run_generic_xdp(skb, xdp, xdp_prog);
+	__skb_pull(*pskb, mac_len);
+
+	act = bpf_prog_run_generic_xdp(*pskb, xdp, xdp_prog);
 	switch (act) {
 	case XDP_REDIRECT:
 	case XDP_TX:
 	case XDP_PASS:
 		break;
 	default:
-		bpf_warn_invalid_xdp_action(skb->dev, xdp_prog, act);
+		bpf_warn_invalid_xdp_action((*pskb)->dev, xdp_prog, act);
 		fallthrough;
 	case XDP_ABORTED:
-		trace_xdp_exception(skb->dev, xdp_prog, act);
+		trace_xdp_exception((*pskb)->dev, xdp_prog, act);
 		fallthrough;
 	case XDP_DROP:
 	do_drop:
-		kfree_skb(skb);
+		kfree_skb(*pskb);
 		break;
 	}
 
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 9e5eb47b4025..bdb94749f05d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -895,6 +895,97 @@ static bool is_pp_page(struct page *page)
 	return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
 }
 
+static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
+			   unsigned int headroom)
+{
+#if IS_ENABLED(CONFIG_PAGE_POOL)
+	u32 size, truesize, len, max_head_size, off;
+	struct sk_buff *skb = *pskb, *nskb;
+	int err, i, head_off;
+	void *data;
+
+	/* XDP does not support fraglist so we need to linearize
+	 * the skb.
+	 */
+	if (skb_has_frag_list(skb))
+		return -EOPNOTSUPP;
+
+	max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - headroom);
+	if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE)
+		return -ENOMEM;
+
+	size = min_t(u32, skb->len, max_head_size);
+	truesize = SKB_HEAD_ALIGN(size) + headroom;
+	data = page_pool_dev_alloc_va(pool, &truesize);
+	if (!data)
+		return -ENOMEM;
+
+	nskb = napi_build_skb(data, truesize);
+	if (!nskb) {
+		page_pool_free_va(pool, data, true);
+		return -ENOMEM;
+	}
+
+	skb_reserve(nskb, headroom);
+	skb_copy_header(nskb, skb);
+	skb_mark_for_recycle(nskb);
+
+	err = skb_copy_bits(skb, 0, nskb->data, size);
+	if (err) {
+		consume_skb(nskb);
+		return err;
+	}
+	skb_put(nskb, size);
+
+	head_off = skb_headroom(nskb) - skb_headroom(skb);
+	skb_headers_offset_update(nskb, head_off);
+
+	off = size;
+	len = skb->len - off;
+	for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
+		struct page *page;
+		u32 page_off;
+
+		size = min_t(u32, len, PAGE_SIZE);
+		truesize = size;
+
+		page = page_pool_dev_alloc(pool, &page_off, &truesize);
+		if (!data) {
+			consume_skb(nskb);
+			return -ENOMEM;
+		}
+
+		skb_add_rx_frag(nskb, i, page, page_off, size, truesize);
+		err = skb_copy_bits(skb, off, page_address(page) + page_off,
+				    size);
+		if (err) {
+			consume_skb(nskb);
+			return err;
+		}
+
+		len -= size;
+		off += size;
+	}
+
+	consume_skb(skb);
+	*pskb = nskb;
+
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
+			 struct bpf_prog *prog)
+{
+	if (!prog->aux->xdp_has_frags)
+		return -EINVAL;
+
+	return skb_pp_cow_data(pool, pskb, XDP_PACKET_HEADROOM);
+}
+EXPORT_SYMBOL(skb_cow_data_for_xdp);
+
 #if IS_ENABLED(CONFIG_PAGE_POOL)
 bool napi_pp_put_page(struct page *page, bool napi_safe)
 {
-- 
2.43.0

Re: [PATCH v9 net-next 3/4] xdp: add multi-buff support for xdp running in generic mode

[Julian Wiedmann]

On 12.02.24 11:50, Lorenzo Bianconi wrote:
> Similar to native xdp, do not always linearize the skb in
> netif_receive_generic_xdp routine but create a non-linear xdp_buff to be
> processed by the eBPF program. This allow to add multi-buffer support
> for xdp running in generic mode.
> 
> Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
> Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> ---
>  include/linux/skbuff.h |  2 +
>  net/core/dev.c         | 70 +++++++++++++++++++++++---------
>  net/core/skbuff.c      | 91 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 144 insertions(+), 19 deletions(-)
> 

[...]

> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 9e5eb47b4025..bdb94749f05d 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -895,6 +895,97 @@ static bool is_pp_page(struct page *page)
>  	return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
>  }
>  
> +static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
> +			   unsigned int headroom)
> +{
> +#if IS_ENABLED(CONFIG_PAGE_POOL)
> +	u32 size, truesize, len, max_head_size, off;
> +	struct sk_buff *skb = *pskb, *nskb;
> +	int err, i, head_off;
> +	void *data;
> +
> +	/* XDP does not support fraglist so we need to linearize
> +	 * the skb.
> +	 */
> +	if (skb_has_frag_list(skb))
> +		return -EOPNOTSUPP;
> +
> +	max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE - headroom);
> +	if (skb->len > max_head_size + MAX_SKB_FRAGS * PAGE_SIZE)
> +		return -ENOMEM;
> +
> +	size = min_t(u32, skb->len, max_head_size);
> +	truesize = SKB_HEAD_ALIGN(size) + headroom;
> +	data = page_pool_dev_alloc_va(pool, &truesize);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	nskb = napi_build_skb(data, truesize);
> +	if (!nskb) {
> +		page_pool_free_va(pool, data, true);
> +		return -ENOMEM;
> +	}
> +
> +	skb_reserve(nskb, headroom);
> +	skb_copy_header(nskb, skb);
> +	skb_mark_for_recycle(nskb);
> +
> +	err = skb_copy_bits(skb, 0, nskb->data, size);
> +	if (err) {
> +		consume_skb(nskb);
> +		return err;
> +	}
> +	skb_put(nskb, size);
> +
> +	head_off = skb_headroom(nskb) - skb_headroom(skb);
> +	skb_headers_offset_update(nskb, head_off);
> +
> +	off = size;
> +	len = skb->len - off;
> +	for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
> +		struct page *page;
> +		u32 page_off;
> +
> +		size = min_t(u32, len, PAGE_SIZE);
> +		truesize = size;
> +
> +		page = page_pool_dev_alloc(pool, &page_off, &truesize);
> +		if (!data) {
> +			consume_skb(nskb);
> +			return -ENOMEM;
> +		}
> +

This should check for !page instead, no?

(picked up as CID 1583654 by the coverity scan for linux-next)

Re: [PATCH v9 net-next 3/4] xdp: add multi-buff support for xdp running in generic mode

[Lorenzo Bianconi]

[-- Attachment #1: Type: text/plain, Size: 1154 bytes --]

[...]
> > +	nskb = napi_build_skb(data, truesize);
> > +	if (!nskb) {
> > +		page_pool_free_va(pool, data, true);
> > +		return -ENOMEM;
> > +	}
> > +
> > +	skb_reserve(nskb, headroom);
> > +	skb_copy_header(nskb, skb);
> > +	skb_mark_for_recycle(nskb);
> > +
> > +	err = skb_copy_bits(skb, 0, nskb->data, size);
> > +	if (err) {
> > +		consume_skb(nskb);
> > +		return err;
> > +	}
> > +	skb_put(nskb, size);
> > +
> > +	head_off = skb_headroom(nskb) - skb_headroom(skb);
> > +	skb_headers_offset_update(nskb, head_off);
> > +
> > +	off = size;
> > +	len = skb->len - off;
> > +	for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
> > +		struct page *page;
> > +		u32 page_off;
> > +
> > +		size = min_t(u32, len, PAGE_SIZE);
> > +		truesize = size;
> > +
> > +		page = page_pool_dev_alloc(pool, &page_off, &truesize);
> > +		if (!data) {

ack, right. I will post a fix, thx for reporting the issue.

Regards,
Lorenzo

> > +			consume_skb(nskb);
> > +			return -ENOMEM;
> > +		}
> > +
> 
> This should check for !page instead, no?
> 
> (picked up as CID 1583654 by the coverity scan for linux-next)
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

[PATCH v9 net-next 4/4] veth: rely on skb_pp_cow_data utility routine

[Lorenzo Bianconi]

Rely on skb_pp_cow_data utility routine and remove duplicated code.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/veth.c     | 74 ++----------------------------------------
 include/linux/skbuff.h |  2 ++
 net/core/skbuff.c      |  5 +--
 3 files changed, 7 insertions(+), 74 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 578e36ea1589..4116e4c4072c 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -729,80 +729,10 @@ static int veth_convert_skb_to_xdp_buff(struct veth_rq *rq,
 	if (skb_shared(skb) || skb_head_is_locked(skb) ||
 	    skb_shinfo(skb)->nr_frags ||
 	    skb_headroom(skb) < XDP_PACKET_HEADROOM) {
-		u32 size, len, max_head_size, off, truesize, page_offset;
-		struct sk_buff *nskb;
-		struct page *page;
-		int i, head_off;
-		void *va;
-
-		/* We need a private copy of the skb and data buffers since
-		 * the ebpf program can modify it. We segment the original skb
-		 * into order-0 pages without linearize it.
-		 *
-		 * Make sure we have enough space for linear and paged area
-		 */
-		max_head_size = SKB_WITH_OVERHEAD(PAGE_SIZE -
-						  VETH_XDP_HEADROOM);
-		if (skb->len > PAGE_SIZE * MAX_SKB_FRAGS + max_head_size)
-			goto drop;
-
-		size = min_t(u32, skb->len, max_head_size);
-		truesize = SKB_HEAD_ALIGN(size) + VETH_XDP_HEADROOM;
-
-		/* Allocate skb head */
-		va = page_pool_dev_alloc_va(rq->page_pool, &truesize);
-		if (!va)
-			goto drop;
-
-		nskb = napi_build_skb(va, truesize);
-		if (!nskb) {
-			page_pool_free_va(rq->page_pool, va, true);
+		if (skb_pp_cow_data(rq->page_pool, pskb, XDP_PACKET_HEADROOM))
 			goto drop;
-		}
-
-		skb_reserve(nskb, VETH_XDP_HEADROOM);
-		skb_copy_header(nskb, skb);
-		skb_mark_for_recycle(nskb);
-
-		if (skb_copy_bits(skb, 0, nskb->data, size)) {
-			consume_skb(nskb);
-			goto drop;
-		}
-		skb_put(nskb, size);
 
-		head_off = skb_headroom(nskb) - skb_headroom(skb);
-		skb_headers_offset_update(nskb, head_off);
-
-		/* Allocate paged area of new skb */
-		off = size;
-		len = skb->len - off;
-
-		for (i = 0; i < MAX_SKB_FRAGS && off < skb->len; i++) {
-			size = min_t(u32, len, PAGE_SIZE);
-			truesize = size;
-
-			page = page_pool_dev_alloc(rq->page_pool, &page_offset,
-						   &truesize);
-			if (!page) {
-				consume_skb(nskb);
-				goto drop;
-			}
-
-			skb_add_rx_frag(nskb, i, page, page_offset, size,
-					truesize);
-			if (skb_copy_bits(skb, off,
-					  page_address(page) + page_offset,
-					  size)) {
-				consume_skb(nskb);
-				goto drop;
-			}
-
-			len -= size;
-			off += size;
-		}
-
-		consume_skb(skb);
-		skb = nskb;
+		skb = *pskb;
 	}
 
 	/* SKB "head" area always have tailroom for skb_shared_info */
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index def3d8689c3d..696e7680656f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3446,6 +3446,8 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
 	__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
 }
 
+int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
+		    unsigned int headroom);
 int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
 			 struct bpf_prog *prog);
 bool napi_pp_put_page(struct page *page, bool napi_safe);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index bdb94749f05d..0d9a489e6ae1 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -895,8 +895,8 @@ static bool is_pp_page(struct page *page)
 	return (page->pp_magic & ~0x3UL) == PP_SIGNATURE;
 }
 
-static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
-			   unsigned int headroom)
+int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
+		    unsigned int headroom)
 {
 #if IS_ENABLED(CONFIG_PAGE_POOL)
 	u32 size, truesize, len, max_head_size, off;
@@ -975,6 +975,7 @@ static int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
 	return -EOPNOTSUPP;
 #endif
 }
+EXPORT_SYMBOL(skb_pp_cow_data);
 
 int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
 			 struct bpf_prog *prog)
-- 
2.43.0

Re: [PATCH v9 net-next 0/4] add multi-buff support for xdp running in generic mode

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 12 Feb 2024 10:50:53 +0100 you wrote:
> Introduce multi-buffer support for xdp running in generic mode not always
> linearizing the skb in netif_receive_generic_xdp routine.
> Introduce generic percpu page_pools allocator.
> 
> Changes since v8:
> - fix veth regression introduce in veth.sh selftest
> Changes since v7:
> - fix sparse warnings
> Changes since v6:
> - remove patch 4/5 'net: page_pool: make stats available just for global pools'
> - rename netif_skb_segment_for_xdp() in
>   skb_cow_data_for_xdp()/skb_pp_cow_data()
> - rename net_page_pool_alloc() in net_page_pool_create()
> - rename page_pool percpu pointer in system_page_pool
> - set percpu page_pool memory size
> Changes since v5:
> - move percpu page_pool pointer out of softnet_data in a dedicated variable
> - make page_pool stats available just for global pools
> - rely on netif_skb_segment_for_xdp utility routine in veth driver
> Changes since v4:
> - fix compilation error if page_pools are not enabled
> Changes since v3:
> - introduce page_pool in softnet_data structure
> - rely on page_pools for xdp_generic code
> Changes since v2:
> - rely on napi_alloc_frag() and napi_build_skb() to build the new skb
> Changes since v1:
> - explicitly keep the skb segmented in netif_skb_check_for_generic_xdp() and
>   do not rely on pskb_expand_head()
> 
> [...]

Here is the summary with links:
  - [v9,net-next,1/4] net: add generic percpu page_pool allocator
    https://git.kernel.org/netdev/net-next/c/2b0cfa6e4956
  - [v9,net-next,2/4] xdp: rely on skb pointer reference in do_xdp_generic and netif_receive_generic_xdp
    https://git.kernel.org/netdev/net-next/c/4d2bb0bfe874
  - [v9,net-next,3/4] xdp: add multi-buff support for xdp running in generic mode
    https://git.kernel.org/netdev/net-next/c/e6d5dbdd20aa
  - [v9,net-next,4/4] veth: rely on skb_pp_cow_data utility routine
    https://git.kernel.org/netdev/net-next/c/27accb3cc08a

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html