[PATCH bpf-next v5 0/7] Add support for transmitting packets using XDP in bpf_prog_run()

[PATCH bpf-next v5 0/7] Add support for transmitting packets using XDP in bpf_prog_run()

[Toke Høiland-Jørgensen]

This series adds support for transmitting packets using XDP in
bpf_prog_run(), by enabling a new mode "live packet" mode which will handle
the XDP program return codes and redirect the packets to the stack or other
devices.

The primary use case for this is testing the redirect map types and the
ndo_xdp_xmit driver operation without an external traffic generator. But it
turns out to also be useful for creating a programmable traffic generator
in XDP, as well as injecting frames into the stack. A sample traffic
generator, which was included in previous versions of the series, but now
moved to xdp-tools, transmits up to 11.5 Mpps/core on my test machine.

To transmit the frames, the new mode instantiates a page_pool structure in
bpf_prog_run() and initialises the pages to contain XDP frames with the
data passed in by userspace. These frames can then be handled as though
they came from the hardware XDP path, and the existing page_pool code takes
care of returning and recycling them. The setup is optimised for high
performance with a high number of repetitions to support stress testing and
the traffic generator use case; see patch 6 for details.

The series is structured as follows: Patches 1-5 adds a few features to
page_pool that are needed for the usage in bpf_prog_run() and perform a
couple of preparatory refactorings of the XDP redirect and memory
management code. Patch 6 adds the support to bpf_prog_run() itself and
patch 7 adds a selftest that exercises all the XDP return codes.

v5:
- Rebase to current bpf-next

v4:
- Fix a few code style issues (Alexei)
- Also handle the other return codes: XDP_PASS builds skbs and injects them
  into the stack, and XDP_TX is turned into a redirect out the same
  interface (Alexei).
- Drop the last patch adding an xdp_trafficgen program to samples/bpf; this
  will live in xdp-tools instead (Alexei).
- Add a separate bpf_test_run_xdp_live() function to test_run.c instead of
  entangling the new mode in the existing bpf_test_run().

v3:
- Reorder patches to make sure they all build individually (Patchwork)
- Remove a couple of unused variables (Patchwork)
- Remove unlikely() annotation in slow path and add back John's ACK that I
  accidentally dropped for v2 (John)

v2:
- Split up up __xdp_do_redirect to avoid passing two pointers to it (John)
- Always reset context pointers before each test run (John)
- Use get_mac_addr() from xdp_sample_user.h instead of rolling our own (Kumar)
- Fix wrong offset for metadata pointer

Toke Høiland-Jørgensen (7):
  xdp: Allow registering memory model without rxq reference
  page_pool: Add callback to init pages when they are allocated
  page_pool: Store the XDP mem id
  xdp: Move conversion to xdp_frame out of map functions
  xdp: add xdp_do_redirect_frame() for pre-computed xdp_frames
  bpf: Add "live packet" mode for XDP in bpf_prog_run()
  selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

 include/linux/bpf.h                           |  20 +-
 include/linux/filter.h                        |   4 +
 include/net/page_pool.h                       |  11 +-
 include/net/xdp.h                             |   3 +
 include/uapi/linux/bpf.h                      |   2 +
 kernel/bpf/Kconfig                            |   1 +
 kernel/bpf/cpumap.c                           |   8 +-
 kernel/bpf/devmap.c                           |  32 +-
 net/bpf/test_run.c                            | 287 +++++++++++++++++-
 net/core/filter.c                             |  73 ++++-
 net/core/page_pool.c                          |   6 +-
 net/core/xdp.c                                |  94 ++++--
 tools/include/uapi/linux/bpf.h                |   2 +
 .../bpf/prog_tests/xdp_do_redirect.c          | 118 +++++++
 .../bpf/progs/test_xdp_do_redirect.c          |  39 +++
 15 files changed, 610 insertions(+), 90 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c

-- 
2.34.1

[PATCH bpf-next v5 1/7] xdp: Allow registering memory model without rxq reference

[Toke Høiland-Jørgensen]

The functions that register an XDP memory model take a struct xdp_rxq as
parameter, but the RXQ is not actually used for anything other than pulling
out the struct xdp_mem_info that it embeds. So refactor the register
functions and export variants that just take a pointer to the xdp_mem_info.

This is in preparation for enabling XDP_REDIRECT in bpf_prog_run(), using a
page_pool instance that is not connected to any network device.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 include/net/xdp.h |  3 ++
 net/core/xdp.c    | 92 +++++++++++++++++++++++++++++++----------------
 2 files changed, 65 insertions(+), 30 deletions(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 447f9b1578f3..8f0812e4996d 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -260,6 +260,9 @@ bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 			       enum xdp_mem_type type, void *allocator);
 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
+int xdp_reg_mem_model(struct xdp_mem_info *mem,
+		      enum xdp_mem_type type, void *allocator);
+void xdp_unreg_mem_model(struct xdp_mem_info *mem);
 
 /* Drivers not supporting XDP metadata can use this helper, which
  * rejects any room expansion for metadata as a result.
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 7fe1df85f505..58089f6d2c7a 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -110,20 +110,15 @@ static void mem_allocator_disconnect(void *allocator)
 	mutex_unlock(&mem_id_lock);
 }
 
-void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
+void xdp_unreg_mem_model(struct xdp_mem_info *mem)
 {
 	struct xdp_mem_allocator *xa;
-	int type = xdp_rxq->mem.type;
-	int id = xdp_rxq->mem.id;
+	int type = mem->type;
+	int id = mem->id;
 
 	/* Reset mem info to defaults */
-	xdp_rxq->mem.id = 0;
-	xdp_rxq->mem.type = 0;
-
-	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
-		WARN(1, "Missing register, driver bug");
-		return;
-	}
+	mem->id = 0;
+	mem->type = 0;
 
 	if (id == 0)
 		return;
@@ -135,6 +130,17 @@ void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
 		rcu_read_unlock();
 	}
 }
+EXPORT_SYMBOL_GPL(xdp_unreg_mem_model);
+
+void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
+{
+	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
+		WARN(1, "Missing register, driver bug");
+		return;
+	}
+
+	xdp_unreg_mem_model(&xdp_rxq->mem);
+}
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);
 
 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
@@ -259,28 +265,24 @@ static bool __is_supported_mem_type(enum xdp_mem_type type)
 	return true;
 }
 
-int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
-			       enum xdp_mem_type type, void *allocator)
+static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
+						     enum xdp_mem_type type,
+						     void *allocator)
 {
 	struct xdp_mem_allocator *xdp_alloc;
 	gfp_t gfp = GFP_KERNEL;
 	int id, errno, ret;
 	void *ptr;
 
-	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
-		WARN(1, "Missing register, driver bug");
-		return -EFAULT;
-	}
-
 	if (!__is_supported_mem_type(type))
-		return -EOPNOTSUPP;
+		return ERR_PTR(-EOPNOTSUPP);
 
-	xdp_rxq->mem.type = type;
+	mem->type = type;
 
 	if (!allocator) {
 		if (type == MEM_TYPE_PAGE_POOL)
-			return -EINVAL; /* Setup time check page_pool req */
-		return 0;
+			return ERR_PTR(-EINVAL); /* Setup time check page_pool req */
+		return NULL;
 	}
 
 	/* Delay init of rhashtable to save memory if feature isn't used */
@@ -290,13 +292,13 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 		mutex_unlock(&mem_id_lock);
 		if (ret < 0) {
 			WARN_ON(1);
-			return ret;
+			return ERR_PTR(ret);
 		}
 	}
 
 	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
 	if (!xdp_alloc)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	mutex_lock(&mem_id_lock);
 	id = __mem_id_cyclic_get(gfp);
@@ -304,15 +306,15 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 		errno = id;
 		goto err;
 	}
-	xdp_rxq->mem.id = id;
-	xdp_alloc->mem  = xdp_rxq->mem;
+	mem->id = id;
+	xdp_alloc->mem = *mem;
 	xdp_alloc->allocator = allocator;
 
 	/* Insert allocator into ID lookup table */
 	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
 	if (IS_ERR(ptr)) {
-		ida_simple_remove(&mem_id_pool, xdp_rxq->mem.id);
-		xdp_rxq->mem.id = 0;
+		ida_simple_remove(&mem_id_pool, mem->id);
+		mem->id = 0;
 		errno = PTR_ERR(ptr);
 		goto err;
 	}
@@ -322,13 +324,43 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 
 	mutex_unlock(&mem_id_lock);
 
-	trace_mem_connect(xdp_alloc, xdp_rxq);
-	return 0;
+	return xdp_alloc;
 err:
 	mutex_unlock(&mem_id_lock);
 	kfree(xdp_alloc);
-	return errno;
+	return ERR_PTR(errno);
+}
+
+int xdp_reg_mem_model(struct xdp_mem_info *mem,
+		      enum xdp_mem_type type, void *allocator)
+{
+	struct xdp_mem_allocator *xdp_alloc;
+
+	xdp_alloc = __xdp_reg_mem_model(mem, type, allocator);
+	if (IS_ERR(xdp_alloc))
+		return PTR_ERR(xdp_alloc);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xdp_reg_mem_model);
+
+int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
+			       enum xdp_mem_type type, void *allocator)
+{
+	struct xdp_mem_allocator *xdp_alloc;
+
+	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
+		WARN(1, "Missing register, driver bug");
+		return -EFAULT;
+	}
+
+	xdp_alloc = __xdp_reg_mem_model(&xdp_rxq->mem, type, allocator);
+	if (IS_ERR(xdp_alloc))
+		return PTR_ERR(xdp_alloc);
+
+	trace_mem_connect(xdp_alloc, xdp_rxq);
+	return 0;
 }
+
 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
 
 /* XDP RX runs under NAPI protection, and in different delivery error
-- 
2.34.1

[PATCH bpf-next v5 2/7] page_pool: Add callback to init pages when they are allocated

[Toke Høiland-Jørgensen]

Add a new callback function to page_pool that, if set, will be called every
time a new page is allocated. This will be used from bpf_test_run() to
initialise the page data with the data provided by userspace when running
XDP programs with redirect turned on.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 include/net/page_pool.h | 2 ++
 net/core/page_pool.c    | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index a4082406a003..d807b6800a4a 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -80,6 +80,8 @@ struct page_pool_params {
 	enum dma_data_direction dma_dir; /* DMA mapping direction */
 	unsigned int	max_len; /* max DMA sync memory size */
 	unsigned int	offset;  /* DMA addr offset */
+	void (*init_callback)(struct page *page, void *arg);
+	void *init_arg;
 };
 
 struct page_pool {
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1a6978427d6c..f53786f6666d 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -217,6 +217,8 @@ static void page_pool_set_pp_info(struct page_pool *pool,
 {
 	page->pp = pool;
 	page->pp_magic |= PP_SIGNATURE;
+	if (pool->p.init_callback)
+		pool->p.init_callback(page, pool->p.init_arg);
 }
 
 static void page_pool_clear_pp_info(struct page *page)
-- 
2.34.1

Re: [PATCH bpf-next v5 2/7] page_pool: Add callback to init pages when they are allocated

[Jesper Dangaard Brouer]

On 03/01/2022 16.08, Toke Høiland-Jørgensen wrote:
> Add a new callback function to page_pool that, if set, will be called every
> time a new page is allocated. This will be used from bpf_test_run() to
> initialise the page data with the data provided by userspace when running
> XDP programs with redirect turned on.
> 
> Acked-by: John Fastabend<john.fastabend@gmail.com>
> Signed-off-by: Toke Høiland-Jørgensen<toke@redhat.com>

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

[PATCH bpf-next v5 3/7] page_pool: Store the XDP mem id

[Toke Høiland-Jørgensen]

Store the XDP mem ID inside the page_pool struct so it can be retrieved
later for use in bpf_prog_run().

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 include/net/page_pool.h | 9 +++++++--
 net/core/page_pool.c    | 4 +++-
 net/core/xdp.c          | 2 +-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index d807b6800a4a..79a805542d0f 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -96,6 +96,7 @@ struct page_pool {
 	unsigned int frag_offset;
 	struct page *frag_page;
 	long frag_users;
+	u32 xdp_mem_id;
 
 	/*
 	 * Data structure for allocation side
@@ -170,9 +171,12 @@ bool page_pool_return_skb_page(struct page *page);
 
 struct page_pool *page_pool_create(const struct page_pool_params *params);
 
+struct xdp_mem_info;
+
 #ifdef CONFIG_PAGE_POOL
 void page_pool_destroy(struct page_pool *pool);
-void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *));
+void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
+			   struct xdp_mem_info *mem);
 void page_pool_release_page(struct page_pool *pool, struct page *page);
 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 			     int count);
@@ -182,7 +186,8 @@ static inline void page_pool_destroy(struct page_pool *pool)
 }
 
 static inline void page_pool_use_xdp_mem(struct page_pool *pool,
-					 void (*disconnect)(void *))
+					 void (*disconnect)(void *),
+					 struct xdp_mem_info *mem)
 {
 }
 static inline void page_pool_release_page(struct page_pool *pool,
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index f53786f6666d..7347d5c7dbe0 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -693,10 +693,12 @@ static void page_pool_release_retry(struct work_struct *wq)
 	schedule_delayed_work(&pool->release_dw, DEFER_TIME);
 }
 
-void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *))
+void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
+			   struct xdp_mem_info *mem)
 {
 	refcount_inc(&pool->user_cnt);
 	pool->disconnect = disconnect;
+	pool->xdp_mem_id = mem->id;
 }
 
 void page_pool_destroy(struct page_pool *pool)
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 58089f6d2c7a..7aba35504986 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -320,7 +320,7 @@ static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
 	}
 
 	if (type == MEM_TYPE_PAGE_POOL)
-		page_pool_use_xdp_mem(allocator, mem_allocator_disconnect);
+		page_pool_use_xdp_mem(allocator, mem_allocator_disconnect, mem);
 
 	mutex_unlock(&mem_id_lock);
 
-- 
2.34.1

Re: [PATCH bpf-next v5 3/7] page_pool: Store the XDP mem id

[Jesper Dangaard Brouer]

On 03/01/2022 16.08, Toke Høiland-Jørgensen wrote:
> Store the XDP mem ID inside the page_pool struct so it can be retrieved
> later for use in bpf_prog_run().
> 
> Signed-off-by: Toke Høiland-Jørgensen<toke@redhat.com>
> ---
>   include/net/page_pool.h | 9 +++++++--
>   net/core/page_pool.c    | 4 +++-
>   net/core/xdp.c          | 2 +-
>   3 files changed, 11 insertions(+), 4 deletions(-)

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>

[PATCH bpf-next v5 4/7] xdp: Move conversion to xdp_frame out of map functions

[Toke Høiland-Jørgensen]

All map redirect functions except XSK maps convert xdp_buff to xdp_frame
before enqueueing it. So move this conversion of out the map functions
and into xdp_do_redirect(). This removes a bit of duplicated code, but more
importantly it makes it possible to support caller-allocated xdp_frame
structures, which will be added in a subsequent commit.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 include/linux/bpf.h | 20 ++++++++++----------
 kernel/bpf/cpumap.c |  8 +-------
 kernel/bpf/devmap.c | 32 +++++++++++---------------------
 net/core/filter.c   | 24 +++++++++++++++++-------
 4 files changed, 39 insertions(+), 45 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 26753139d5b4..6e947cd91152 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1669,17 +1669,17 @@ void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth);
 struct btf *bpf_get_btf_vmlinux(void);
 
 /* Map specifics */
-struct xdp_buff;
+struct xdp_frame;
 struct sk_buff;
 struct bpf_dtab_netdev;
 struct bpf_cpu_map_entry;
 
 void __dev_flush(void);
-int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
+int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx);
-int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
+int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx);
-int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
+int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
 			  struct bpf_map *map, bool exclude_ingress);
 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 			     struct bpf_prog *xdp_prog);
@@ -1688,7 +1688,7 @@ int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
 			   bool exclude_ingress);
 
 void __cpu_map_flush(void);
-int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
+int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx);
 int cpu_map_generic_redirect(struct bpf_cpu_map_entry *rcpu,
 			     struct sk_buff *skb);
@@ -1866,26 +1866,26 @@ static inline void __dev_flush(void)
 {
 }
 
-struct xdp_buff;
+struct xdp_frame;
 struct bpf_dtab_netdev;
 struct bpf_cpu_map_entry;
 
 static inline
-int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
+int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx)
 {
 	return 0;
 }
 
 static inline
-int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
+int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx)
 {
 	return 0;
 }
 
 static inline
-int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
+int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
 			  struct bpf_map *map, bool exclude_ingress)
 {
 	return 0;
@@ -1913,7 +1913,7 @@ static inline void __cpu_map_flush(void)
 }
 
 static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu,
-				  struct xdp_buff *xdp,
+				  struct xdp_frame *xdpf,
 				  struct net_device *dev_rx)
 {
 	return 0;
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 0421061d95f1..b3e6b9422238 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -746,15 +746,9 @@ static void bq_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf)
 		list_add(&bq->flush_node, flush_list);
 }
 
-int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
+int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx)
 {
-	struct xdp_frame *xdpf;
-
-	xdpf = xdp_convert_buff_to_frame(xdp);
-	if (unlikely(!xdpf))
-		return -EOVERFLOW;
-
 	/* Info needed when constructing SKB on remote CPU */
 	xdpf->dev_rx = dev_rx;
 
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 6feea293ff10..fe019dbdb3f0 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -467,24 +467,19 @@ static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 	bq->q[bq->count++] = xdpf;
 }
 
-static inline int __xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
+static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 				struct net_device *dev_rx,
 				struct bpf_prog *xdp_prog)
 {
-	struct xdp_frame *xdpf;
 	int err;
 
 	if (!dev->netdev_ops->ndo_xdp_xmit)
 		return -EOPNOTSUPP;
 
-	err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
+	err = xdp_ok_fwd_dev(dev, xdpf->len);
 	if (unlikely(err))
 		return err;
 
-	xdpf = xdp_convert_buff_to_frame(xdp);
-	if (unlikely(!xdpf))
-		return -EOVERFLOW;
-
 	bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
 	return 0;
 }
@@ -520,27 +515,27 @@ static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev
 	return act;
 }
 
-int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
+int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx)
 {
-	return __xdp_enqueue(dev, xdp, dev_rx, NULL);
+	return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
 }
 
-int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
+int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
 		    struct net_device *dev_rx)
 {
 	struct net_device *dev = dst->dev;
 
-	return __xdp_enqueue(dev, xdp, dev_rx, dst->xdp_prog);
+	return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
 }
 
-static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_buff *xdp)
+static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
 {
 	if (!obj ||
 	    !obj->dev->netdev_ops->ndo_xdp_xmit)
 		return false;
 
-	if (xdp_ok_fwd_dev(obj->dev, xdp->data_end - xdp->data))
+	if (xdp_ok_fwd_dev(obj->dev, xdpf->len))
 		return false;
 
 	return true;
@@ -586,14 +581,13 @@ static int get_upper_ifindexes(struct net_device *dev, int *indexes)
 	return n;
 }
 
-int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
+int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
 			  struct bpf_map *map, bool exclude_ingress)
 {
 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 	struct bpf_dtab_netdev *dst, *last_dst = NULL;
 	int excluded_devices[1+MAX_NEST_DEV];
 	struct hlist_head *head;
-	struct xdp_frame *xdpf;
 	int num_excluded = 0;
 	unsigned int i;
 	int err;
@@ -603,15 +597,11 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
 		excluded_devices[num_excluded++] = dev_rx->ifindex;
 	}
 
-	xdpf = xdp_convert_buff_to_frame(xdp);
-	if (unlikely(!xdpf))
-		return -EOVERFLOW;
-
 	if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 		for (i = 0; i < map->max_entries; i++) {
 			dst = rcu_dereference_check(dtab->netdev_map[i],
 						    rcu_read_lock_bh_held());
-			if (!is_valid_dst(dst, xdp))
+			if (!is_valid_dst(dst, xdpf))
 				continue;
 
 			if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
@@ -634,7 +624,7 @@ int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
 			head = dev_map_index_hash(dtab, i);
 			hlist_for_each_entry_rcu(dst, head, index_hlist,
 						 lockdep_is_held(&dtab->index_lock)) {
-				if (!is_valid_dst(dst, xdp))
+				if (!is_valid_dst(dst, xdpf))
 					continue;
 
 				if (is_ifindex_excluded(excluded_devices, num_excluded,
diff --git a/net/core/filter.c b/net/core/filter.c
index 606ab5a98a1a..81b57ea9ad35 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3964,12 +3964,24 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 	enum bpf_map_type map_type = ri->map_type;
 	void *fwd = ri->tgt_value;
 	u32 map_id = ri->map_id;
+	struct xdp_frame *xdpf;
 	struct bpf_map *map;
 	int err;
 
 	ri->map_id = 0; /* Valid map id idr range: [1,INT_MAX[ */
 	ri->map_type = BPF_MAP_TYPE_UNSPEC;
 
+	if (map_type == BPF_MAP_TYPE_XSKMAP) {
+		err = __xsk_map_redirect(fwd, xdp);
+		goto out;
+	}
+
+	xdpf = xdp_convert_buff_to_frame(xdp);
+	if (unlikely(!xdpf)) {
+		err = -EOVERFLOW;
+		goto err;
+	}
+
 	switch (map_type) {
 	case BPF_MAP_TYPE_DEVMAP:
 		fallthrough;
@@ -3977,17 +3989,14 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 		map = READ_ONCE(ri->map);
 		if (unlikely(map)) {
 			WRITE_ONCE(ri->map, NULL);
-			err = dev_map_enqueue_multi(xdp, dev, map,
+			err = dev_map_enqueue_multi(xdpf, dev, map,
 						    ri->flags & BPF_F_EXCLUDE_INGRESS);
 		} else {
-			err = dev_map_enqueue(fwd, xdp, dev);
+			err = dev_map_enqueue(fwd, xdpf, dev);
 		}
 		break;
 	case BPF_MAP_TYPE_CPUMAP:
-		err = cpu_map_enqueue(fwd, xdp, dev);
-		break;
-	case BPF_MAP_TYPE_XSKMAP:
-		err = __xsk_map_redirect(fwd, xdp);
+		err = cpu_map_enqueue(fwd, xdpf, dev);
 		break;
 	case BPF_MAP_TYPE_UNSPEC:
 		if (map_id == INT_MAX) {
@@ -3996,7 +4005,7 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 				err = -EINVAL;
 				break;
 			}
-			err = dev_xdp_enqueue(fwd, xdp, dev);
+			err = dev_xdp_enqueue(fwd, xdpf, dev);
 			break;
 		}
 		fallthrough;
@@ -4004,6 +4013,7 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 		err = -EBADRQC;
 	}
 
+out:
 	if (unlikely(err))
 		goto err;
 
-- 
2.34.1

[PATCH bpf-next v5 5/7] xdp: add xdp_do_redirect_frame() for pre-computed xdp_frames

[Toke Høiland-Jørgensen]

Add an xdp_do_redirect_frame() variant which supports pre-computed
xdp_frame structures. This will be used in bpf_prog_run() to avoid having
to write to the xdp_frame structure when the XDP program doesn't modify the
frame boundaries.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 include/linux/filter.h |  4 +++
 net/core/filter.c      | 65 +++++++++++++++++++++++++++++++++++-------
 2 files changed, 58 insertions(+), 11 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 60eec80fa1d4..71fa57b88bfc 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1019,6 +1019,10 @@ int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
 int xdp_do_redirect(struct net_device *dev,
 		    struct xdp_buff *xdp,
 		    struct bpf_prog *prog);
+int xdp_do_redirect_frame(struct net_device *dev,
+			  struct xdp_buff *xdp,
+			  struct xdp_frame *xdpf,
+			  struct bpf_prog *prog);
 void xdp_do_flush(void);
 
 /* The xdp_do_flush_map() helper has been renamed to drop the _map suffix, as
diff --git a/net/core/filter.c b/net/core/filter.c
index 81b57ea9ad35..cceb4cf52519 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3957,26 +3957,44 @@ u32 xdp_master_redirect(struct xdp_buff *xdp)
 }
 EXPORT_SYMBOL_GPL(xdp_master_redirect);
 
-int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
-		    struct bpf_prog *xdp_prog)
+static inline int __xdp_do_redirect_xsk(struct bpf_redirect_info *ri,
+					struct net_device *dev,
+					struct xdp_buff *xdp,
+					struct bpf_prog *xdp_prog)
 {
-	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 	enum bpf_map_type map_type = ri->map_type;
 	void *fwd = ri->tgt_value;
 	u32 map_id = ri->map_id;
-	struct xdp_frame *xdpf;
-	struct bpf_map *map;
 	int err;
 
 	ri->map_id = 0; /* Valid map id idr range: [1,INT_MAX[ */
 	ri->map_type = BPF_MAP_TYPE_UNSPEC;
 
-	if (map_type == BPF_MAP_TYPE_XSKMAP) {
-		err = __xsk_map_redirect(fwd, xdp);
-		goto out;
-	}
+	err = __xsk_map_redirect(fwd, xdp);
+	if (unlikely(err))
+		goto err;
+
+	_trace_xdp_redirect_map(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index);
+	return 0;
+err:
+	_trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index, err);
+	return err;
+}
+
+static __always_inline int __xdp_do_redirect_frame(struct bpf_redirect_info *ri,
+						   struct net_device *dev,
+						   struct xdp_frame *xdpf,
+						   struct bpf_prog *xdp_prog)
+{
+	enum bpf_map_type map_type = ri->map_type;
+	void *fwd = ri->tgt_value;
+	u32 map_id = ri->map_id;
+	struct bpf_map *map;
+	int err;
+
+	ri->map_id = 0; /* Valid map id idr range: [1,INT_MAX[ */
+	ri->map_type = BPF_MAP_TYPE_UNSPEC;
 
-	xdpf = xdp_convert_buff_to_frame(xdp);
 	if (unlikely(!xdpf)) {
 		err = -EOVERFLOW;
 		goto err;
@@ -4013,7 +4031,6 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 		err = -EBADRQC;
 	}
 
-out:
 	if (unlikely(err))
 		goto err;
 
@@ -4023,8 +4040,34 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 	_trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map_type, map_id, ri->tgt_index, err);
 	return err;
 }
+
+int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
+		    struct bpf_prog *xdp_prog)
+{
+	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+	enum bpf_map_type map_type = ri->map_type;
+
+	if (map_type == BPF_MAP_TYPE_XSKMAP)
+		return __xdp_do_redirect_xsk(ri, dev, xdp, xdp_prog);
+
+	return __xdp_do_redirect_frame(ri, dev, xdp_convert_buff_to_frame(xdp),
+				       xdp_prog);
+}
 EXPORT_SYMBOL_GPL(xdp_do_redirect);
 
+int xdp_do_redirect_frame(struct net_device *dev, struct xdp_buff *xdp,
+			  struct xdp_frame *xdpf, struct bpf_prog *xdp_prog)
+{
+	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+	enum bpf_map_type map_type = ri->map_type;
+
+	if (map_type == BPF_MAP_TYPE_XSKMAP)
+		return __xdp_do_redirect_xsk(ri, dev, xdp, xdp_prog);
+
+	return __xdp_do_redirect_frame(ri, dev, xdpf, xdp_prog);
+}
+EXPORT_SYMBOL_GPL(xdp_do_redirect_frame);
+
 static int xdp_do_generic_redirect_map(struct net_device *dev,
 				       struct sk_buff *skb,
 				       struct xdp_buff *xdp,
-- 
2.34.1

[PATCH bpf-next v5 6/7] bpf: Add "live packet" mode for XDP in bpf_prog_run()

[Toke Høiland-Jørgensen]

This adds support for running XDP programs through bpf_prog_run() in a mode
that enables live packet processing of the resulting frames. Previous uses
of bpf_prog_run() for XDP returned the XDP program return code and the
modified packet data to userspace, which is useful for unit testing of XDP
programs.

This patch adds a new mode with different semantics. When enabled through
the new BPF_F_TEST_XDP_LIVE_FRAMES flag, the XDP program return codes will
be honoured: returning XDP_PASS will result in the frame being injected
into the networking stack as if it came from the selected networking
interface, while returning XDP_TX and XDP_REDIRECT will result in the frame
being transmitted out an egress interface. XDP_TX is translated into an
XDP_REDIRECT operation, since the real XDP_TX action is only possible from
within the network drivers themselves, not from the process context where
bpf_prog_run() is executed.

To achieve this new mode of operation, we create a page pool instance while
setting up the test run, and feed pages from that into the XDP program. The
setup cost of this is amortised over the number of repetitions specified by
userspace.

To support performance testing use case, we further optimise the setup step
so that all pages in the pool are pre-initialised with the packet data, and
pre-computed context and xdp_frame objects stored at the start of each
page. This makes it possible to entirely avoid touching the page content on
each XDP program invocation, and enables sending up to 11.5 Mpps/core on my
test box.

Because the data pages are recycled by the page pool, and the test runner
doesn't re-initialise them for each run, subsequent invocations of the XDP
program will see the packet data in the state it was after the last time it
ran on that particular page. This means that an XDP program that modifies
the packet before redirecting it has to be careful about which assumptions
it makes about the packet content, but that is only an issue for the most
naively written programs.

Enabling the new flag is only allowed when not setting ctx_out and data_out
in the test specification, since using it means frames will be redirected
somewhere else, so they can't be returned.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 include/uapi/linux/bpf.h       |   2 +
 kernel/bpf/Kconfig             |   1 +
 net/bpf/test_run.c             | 287 ++++++++++++++++++++++++++++++++-
 tools/include/uapi/linux/bpf.h |   2 +
 4 files changed, 284 insertions(+), 8 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b0383d371b9a..5ef20deaf49f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1225,6 +1225,8 @@ enum {
 
 /* If set, run the test on the cpu specified by bpf_attr.test.cpu */
 #define BPF_F_TEST_RUN_ON_CPU	(1U << 0)
+/* If set, XDP frames will be transmitted after processing */
+#define BPF_F_TEST_XDP_LIVE_FRAMES	(1U << 1)
 
 /* type for BPF_ENABLE_STATS */
 enum bpf_stats_type {
diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index d24d518ddd63..c8c920020d11 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -30,6 +30,7 @@ config BPF_SYSCALL
 	select TASKS_TRACE_RCU
 	select BINARY_PRINTF
 	select NET_SOCK_MSG if NET
+	select PAGE_POOL if NET
 	default n
 	help
 	  Enable the bpf() system call that allows to manipulate BPF programs
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 46dd95755967..11543819f0ef 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -14,6 +14,7 @@
 #include <net/sock.h>
 #include <net/tcp.h>
 #include <net/net_namespace.h>
+#include <net/page_pool.h>
 #include <linux/error-injection.h>
 #include <linux/smp.h>
 #include <linux/sock_diag.h>
@@ -52,10 +53,11 @@ static void bpf_test_timer_leave(struct bpf_test_timer *t)
 	rcu_read_unlock();
 }
 
-static bool bpf_test_timer_continue(struct bpf_test_timer *t, u32 repeat, int *err, u32 *duration)
+static bool bpf_test_timer_continue(struct bpf_test_timer *t, int iterations,
+				    u32 repeat, int *err, u32 *duration)
 	__must_hold(rcu)
 {
-	t->i++;
+	t->i += iterations;
 	if (t->i >= repeat) {
 		/* We're done. */
 		t->time_spent += ktime_get_ns() - t->time_start;
@@ -87,6 +89,267 @@ static bool bpf_test_timer_continue(struct bpf_test_timer *t, u32 repeat, int *e
 	return false;
 }
 
+/* We put this struct at the head of each page with a context and frame
+ * initialised when the page is allocated, so we don't have to do this on each
+ * repetition of the test run.
+ */
+struct xdp_page_head {
+	struct xdp_buff orig_ctx;
+	struct xdp_buff ctx;
+	struct xdp_frame frm;
+	u8 data[];
+};
+
+struct xdp_test_data {
+	struct xdp_buff *orig_ctx;
+	struct xdp_rxq_info rxq;
+	struct net_device *dev;
+	struct page_pool *pp;
+	u32 frame_cnt;
+};
+
+#define TEST_XDP_FRAME_SIZE (PAGE_SIZE - sizeof(struct xdp_page_head)	\
+			     - sizeof(struct skb_shared_info))
+#define TEST_XDP_BATCH 64
+
+static void xdp_test_run_init_page(struct page *page, void *arg)
+{
+	struct xdp_page_head *head = phys_to_virt(page_to_phys(page));
+	struct xdp_buff *new_ctx, *orig_ctx;
+	u32 headroom = XDP_PACKET_HEADROOM;
+	struct xdp_test_data *xdp = arg;
+	size_t frm_len, meta_len;
+	struct xdp_frame *frm;
+	void *data;
+
+	orig_ctx = xdp->orig_ctx;
+	frm_len = orig_ctx->data_end - orig_ctx->data_meta;
+	meta_len = orig_ctx->data - orig_ctx->data_meta;
+	headroom -= meta_len;
+
+	new_ctx = &head->ctx;
+	frm = &head->frm;
+	data = &head->data;
+	memcpy(data + headroom, orig_ctx->data_meta, frm_len);
+
+	xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq);
+	xdp_prepare_buff(new_ctx, data, headroom, frm_len, true);
+	new_ctx->data_meta = new_ctx->data + meta_len;
+
+	xdp_update_frame_from_buff(new_ctx, frm);
+	frm->mem = new_ctx->rxq->mem;
+
+	memcpy(&head->orig_ctx, new_ctx, sizeof(head->orig_ctx));
+}
+
+static int xdp_test_run_setup(struct xdp_test_data *xdp, struct xdp_buff *orig_ctx)
+{
+	struct xdp_mem_info mem = {};
+	struct page_pool *pp;
+	int err;
+	struct page_pool_params pp_params = {
+		.order = 0,
+		.flags = 0,
+		.pool_size = NAPI_POLL_WEIGHT * 2,
+		.nid = NUMA_NO_NODE,
+		.max_len = TEST_XDP_FRAME_SIZE,
+		.init_callback = xdp_test_run_init_page,
+		.init_arg = xdp,
+	};
+
+	pp = page_pool_create(&pp_params);
+	if (IS_ERR(pp))
+		return PTR_ERR(pp);
+
+	/* will copy 'mem.id' into pp->xdp_mem_id */
+	err = xdp_reg_mem_model(&mem, MEM_TYPE_PAGE_POOL, pp);
+	if (err) {
+		page_pool_destroy(pp);
+		return err;
+	}
+	xdp->pp = pp;
+
+	/* We create a 'fake' RXQ referencing the original dev, but with an
+	 * xdp_mem_info pointing to our page_pool
+	 */
+	xdp_rxq_info_reg(&xdp->rxq, orig_ctx->rxq->dev, 0, 0);
+	xdp->rxq.mem.type = MEM_TYPE_PAGE_POOL;
+	xdp->rxq.mem.id = pp->xdp_mem_id;
+	xdp->dev = orig_ctx->rxq->dev;
+	xdp->orig_ctx = orig_ctx;
+
+	return 0;
+}
+
+static void xdp_test_run_teardown(struct xdp_test_data *xdp)
+{
+	struct xdp_mem_info mem = {
+		.id = xdp->pp->xdp_mem_id,
+		.type = MEM_TYPE_PAGE_POOL,
+	};
+
+	xdp_unreg_mem_model(&mem);
+}
+
+static bool ctx_was_changed(struct xdp_page_head *head)
+{
+	return head->orig_ctx.data != head->ctx.data ||
+		head->orig_ctx.data_meta != head->ctx.data_meta ||
+		head->orig_ctx.data_end != head->ctx.data_end;
+}
+
+static void reset_ctx(struct xdp_page_head *head)
+{
+	if (likely(!ctx_was_changed(head)))
+		return;
+
+	head->ctx.data = head->orig_ctx.data;
+	head->ctx.data_meta = head->orig_ctx.data_meta;
+	head->ctx.data_end = head->orig_ctx.data_end;
+	xdp_update_frame_from_buff(&head->ctx, &head->frm);
+}
+
+static int xdp_recv_frames(struct xdp_frame **frames, int nframes,
+			   struct net_device *dev)
+{
+	gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
+	void *skbs[TEST_XDP_BATCH];
+	int i, n;
+	LIST_HEAD(list);
+
+	n = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, nframes, skbs);
+	if (unlikely(n == 0)) {
+		for (i = 0; i < nframes; i++)
+			xdp_return_frame(frames[i]);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < nframes; i++) {
+		struct xdp_frame *xdpf = frames[i];
+		struct sk_buff *skb = skbs[i];
+
+		skb = __xdp_build_skb_from_frame(xdpf, skb, dev);
+		if (!skb) {
+			xdp_return_frame(xdpf);
+			continue;
+		}
+
+		list_add_tail(&skb->list, &list);
+	}
+	netif_receive_skb_list(&list);
+	return 0;
+}
+
+static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog,
+			      u32 repeat)
+{
+	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+	int err = 0, act, ret, i, nframes = 0, batch_sz;
+	struct xdp_frame *frames[TEST_XDP_BATCH];
+	struct xdp_page_head *head;
+	struct xdp_frame *frm;
+	bool redirect = false;
+	struct xdp_buff *ctx;
+	struct page *page;
+
+	batch_sz = min_t(u32, repeat, TEST_XDP_BATCH);
+	xdp_set_return_frame_no_direct();
+
+	for (i = 0; i < batch_sz; i++) {
+		page = page_pool_dev_alloc_pages(xdp->pp);
+		if (!page) {
+			err = -ENOMEM;
+			goto out;
+		}
+
+		head = phys_to_virt(page_to_phys(page));
+		reset_ctx(head);
+		ctx = &head->ctx;
+		frm = &head->frm;
+		xdp->frame_cnt++;
+
+		act = bpf_prog_run_xdp(prog, ctx);
+
+		/* if program changed pkt bounds we need to update the xdp_frame */
+		if (unlikely(ctx_was_changed(head))) {
+			err = xdp_update_frame_from_buff(ctx, frm);
+			if (err) {
+				xdp_return_buff(ctx);
+				goto out;
+			}
+		}
+
+		switch (act) {
+		case XDP_TX:
+			/* we can't do a real XDP_TX since we're not in the
+			 * driver, so turn it into a REDIRECT back to the same
+			 * index
+			 */
+			ri->tgt_index = xdp->dev->ifindex;
+			ri->map_id = INT_MAX;
+			ri->map_type = BPF_MAP_TYPE_UNSPEC;
+			fallthrough;
+		case XDP_REDIRECT:
+			redirect = true;
+			err = xdp_do_redirect_frame(xdp->dev, ctx, frm, prog);
+			if (err) {
+				xdp_return_buff(ctx);
+				goto out;
+			}
+			break;
+		case XDP_PASS:
+			frames[nframes++] = frm;
+			break;
+		default:
+			bpf_warn_invalid_xdp_action(NULL, prog, act);
+			fallthrough;
+		case XDP_DROP:
+			xdp_return_buff(ctx);
+			break;
+		}
+	}
+
+out:
+	if (redirect)
+		xdp_do_flush();
+	if (nframes) {
+		ret = xdp_recv_frames(frames, nframes, xdp->dev);
+		if (ret)
+			err = ret;
+	}
+
+	xdp_clear_return_frame_no_direct();
+	return err;
+}
+
+static int bpf_test_run_xdp_live(struct bpf_prog *prog, struct xdp_buff *ctx,
+				 u32 repeat, u32 *time)
+
+{
+	struct bpf_test_timer t = { .mode = NO_MIGRATE };
+	struct xdp_test_data xdp = {};
+	int ret;
+
+	if (!repeat)
+		repeat = 1;
+
+	ret = xdp_test_run_setup(&xdp, ctx);
+	if (ret)
+		return ret;
+
+	bpf_test_timer_enter(&t);
+	do {
+		xdp.frame_cnt = 0;
+		ret = xdp_test_run_batch(&xdp, prog, repeat - t.i);
+		if (unlikely(ret < 0))
+			break;
+	} while (bpf_test_timer_continue(&t, xdp.frame_cnt, repeat, &ret, time));
+	bpf_test_timer_leave(&t);
+
+	xdp_test_run_teardown(&xdp);
+	return ret;
+}
+
 static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
 			u32 *retval, u32 *time, bool xdp)
 {
@@ -118,7 +381,7 @@ static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
 			*retval = bpf_prog_run_xdp(prog, ctx);
 		else
 			*retval = bpf_prog_run(prog, ctx);
-	} while (bpf_test_timer_continue(&t, repeat, &ret, time));
+	} while (bpf_test_timer_continue(&t, 1, repeat, &ret, time));
 	bpf_reset_run_ctx(old_ctx);
 	bpf_test_timer_leave(&t);
 
@@ -757,13 +1020,14 @@ static void xdp_convert_buff_to_md(struct xdp_buff *xdp, struct xdp_md *xdp_md)
 int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 			  union bpf_attr __user *uattr)
 {
+	bool do_live = (kattr->test.flags & BPF_F_TEST_XDP_LIVE_FRAMES);
 	u32 tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 	u32 headroom = XDP_PACKET_HEADROOM;
 	u32 size = kattr->test.data_size_in;
 	u32 repeat = kattr->test.repeat;
 	struct netdev_rx_queue *rxqueue;
 	struct xdp_buff xdp = {};
-	u32 retval, duration;
+	u32 retval = 0, duration;
 	struct xdp_md *ctx;
 	u32 max_data_sz;
 	void *data;
@@ -773,6 +1037,9 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 	    prog->expected_attach_type == BPF_XDP_CPUMAP)
 		return -EINVAL;
 
+	if (kattr->test.flags & ~BPF_F_TEST_XDP_LIVE_FRAMES)
+		return -EINVAL;
+
 	ctx = bpf_ctx_init(kattr, sizeof(struct xdp_md));
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
@@ -781,7 +1048,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 		/* There can't be user provided data before the meta data */
 		if (ctx->data_meta || ctx->data_end != size ||
 		    ctx->data > ctx->data_end ||
-		    unlikely(xdp_metalen_invalid(ctx->data)))
+		    unlikely(xdp_metalen_invalid(ctx->data)) ||
+		    (do_live && (kattr->test.data_out || kattr->test.ctx_out)))
 			goto free_ctx;
 		/* Meta data is allocated from the headroom */
 		headroom -= ctx->data;
@@ -807,7 +1075,10 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 
 	if (repeat > 1)
 		bpf_prog_change_xdp(NULL, prog);
-	ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
+	if (do_live)
+		ret = bpf_test_run_xdp_live(prog, &xdp, repeat, &duration);
+	else
+		ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
 	/* We convert the xdp_buff back to an xdp_md before checking the return
 	 * code so the reference count of any held netdevice will be decremented
 	 * even if the test run failed.
@@ -905,7 +1176,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 	do {
 		retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
 					  size, flags);
-	} while (bpf_test_timer_continue(&t, repeat, &ret, &duration));
+	} while (bpf_test_timer_continue(&t, 1, repeat, &ret, &duration));
 	bpf_test_timer_leave(&t);
 
 	if (ret < 0)
@@ -1000,7 +1271,7 @@ int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kat
 	do {
 		ctx.selected_sk = NULL;
 		retval = BPF_PROG_SK_LOOKUP_RUN_ARRAY(progs, ctx, bpf_prog_run);
-	} while (bpf_test_timer_continue(&t, repeat, &ret, &duration));
+	} while (bpf_test_timer_continue(&t, 1, repeat, &ret, &duration));
 	bpf_test_timer_leave(&t);
 
 	if (ret < 0)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b0383d371b9a..5ef20deaf49f 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1225,6 +1225,8 @@ enum {
 
 /* If set, run the test on the cpu specified by bpf_attr.test.cpu */
 #define BPF_F_TEST_RUN_ON_CPU	(1U << 0)
+/* If set, XDP frames will be transmitted after processing */
+#define BPF_F_TEST_XDP_LIVE_FRAMES	(1U << 1)
 
 /* type for BPF_ENABLE_STATS */
 enum bpf_stats_type {
-- 
2.34.1

Re: [PATCH bpf-next v5 6/7] bpf: Add "live packet" mode for XDP in bpf_prog_run()

[Alexei Starovoitov]

On Mon, Jan 03, 2022 at 04:08:11PM +0100, Toke Høiland-Jørgensen wrote:
> +static void xdp_test_run_init_page(struct page *page, void *arg)
> +{
> +	struct xdp_page_head *head = phys_to_virt(page_to_phys(page));
> +	struct xdp_buff *new_ctx, *orig_ctx;
> +	u32 headroom = XDP_PACKET_HEADROOM;
> +	struct xdp_test_data *xdp = arg;
> +	size_t frm_len, meta_len;
> +	struct xdp_frame *frm;
> +	void *data;
> +
> +	orig_ctx = xdp->orig_ctx;
> +	frm_len = orig_ctx->data_end - orig_ctx->data_meta;
> +	meta_len = orig_ctx->data - orig_ctx->data_meta;
> +	headroom -= meta_len;
> +
> +	new_ctx = &head->ctx;
> +	frm = &head->frm;
> +	data = &head->data;
> +	memcpy(data + headroom, orig_ctx->data_meta, frm_len);
> +
> +	xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq);
> +	xdp_prepare_buff(new_ctx, data, headroom, frm_len, true);
> +	new_ctx->data_meta = new_ctx->data + meta_len;

data vs data_meta is the other way around, no?

Probably needs a selftest to make sure.

> +static int xdp_recv_frames(struct xdp_frame **frames, int nframes,
> +			   struct net_device *dev)
> +{
> +	gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
> +	void *skbs[TEST_XDP_BATCH];
> +	int i, n;
> +	LIST_HEAD(list);
> +
> +	n = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, nframes, skbs);
> +	if (unlikely(n == 0)) {
> +		for (i = 0; i < nframes; i++)
> +			xdp_return_frame(frames[i]);
> +		return -ENOMEM;
> +	}
> +
> +	for (i = 0; i < nframes; i++) {
> +		struct xdp_frame *xdpf = frames[i];
> +		struct sk_buff *skb = skbs[i];
> +
> +		skb = __xdp_build_skb_from_frame(xdpf, skb, dev);
> +		if (!skb) {
> +			xdp_return_frame(xdpf);
> +			continue;
> +		}
> +
> +		list_add_tail(&skb->list, &list);
> +	}
> +	netif_receive_skb_list(&list);

Does it need local_bh_disable() like cpumap does?

I've applied patches 1 - 5.

Re: [PATCH bpf-next v5 6/7] bpf: Add "live packet" mode for XDP in bpf_prog_run()

[Toke Høiland-Jørgensen]

Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:

> On Mon, Jan 03, 2022 at 04:08:11PM +0100, Toke Høiland-Jørgensen wrote:
>> +static void xdp_test_run_init_page(struct page *page, void *arg)
>> +{
>> +	struct xdp_page_head *head = phys_to_virt(page_to_phys(page));
>> +	struct xdp_buff *new_ctx, *orig_ctx;
>> +	u32 headroom = XDP_PACKET_HEADROOM;
>> +	struct xdp_test_data *xdp = arg;
>> +	size_t frm_len, meta_len;
>> +	struct xdp_frame *frm;
>> +	void *data;
>> +
>> +	orig_ctx = xdp->orig_ctx;
>> +	frm_len = orig_ctx->data_end - orig_ctx->data_meta;
>> +	meta_len = orig_ctx->data - orig_ctx->data_meta;
>> +	headroom -= meta_len;
>> +
>> +	new_ctx = &head->ctx;
>> +	frm = &head->frm;
>> +	data = &head->data;
>> +	memcpy(data + headroom, orig_ctx->data_meta, frm_len);
>> +
>> +	xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq);
>> +	xdp_prepare_buff(new_ctx, data, headroom, frm_len, true);
>> +	new_ctx->data_meta = new_ctx->data + meta_len;
>
> data vs data_meta is the other way around, no?
>
> Probably needs a selftest to make sure.

Yup, you're right; nice catch! Will fix and add a test for it.

>> +static int xdp_recv_frames(struct xdp_frame **frames, int nframes,
>> +			   struct net_device *dev)
>> +{
>> +	gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
>> +	void *skbs[TEST_XDP_BATCH];
>> +	int i, n;
>> +	LIST_HEAD(list);
>> +
>> +	n = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, nframes, skbs);
>> +	if (unlikely(n == 0)) {
>> +		for (i = 0; i < nframes; i++)
>> +			xdp_return_frame(frames[i]);
>> +		return -ENOMEM;
>> +	}
>> +
>> +	for (i = 0; i < nframes; i++) {
>> +		struct xdp_frame *xdpf = frames[i];
>> +		struct sk_buff *skb = skbs[i];
>> +
>> +		skb = __xdp_build_skb_from_frame(xdpf, skb, dev);
>> +		if (!skb) {
>> +			xdp_return_frame(xdpf);
>> +			continue;
>> +		}
>> +
>> +		list_add_tail(&skb->list, &list);
>> +	}
>> +	netif_receive_skb_list(&list);
>
> Does it need local_bh_disable() like cpumap does?

Yes, I think it probably does, actually. Or at least having it can
potentially improve performance since we're then sure that the whole
batch will be processed at once. Will add!

> I've applied patches 1 - 5.

Thanks! Will respin this and the selftest :)

[PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Toke Høiland-Jørgensen]

This adds a selftest for the XDP_REDIRECT facility in bpf_prog_run, that
redirects packets into a veth and counts them using an XDP program on the
other side of the veth pair.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 .../bpf/prog_tests/xdp_do_redirect.c          | 118 ++++++++++++++++++
 .../bpf/progs/test_xdp_do_redirect.c          |  39 ++++++
 2 files changed, 157 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
new file mode 100644
index 000000000000..a587c351d495
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <network_helpers.h>
+#include <net/if.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/ipv6.h>
+#include <linux/in6.h>
+#include <linux/udp.h>
+#include <bpf/bpf_endian.h>
+#include "test_xdp_do_redirect.skel.h"
+
+#define SYS(fmt, ...)						\
+	({							\
+		char cmd[1024];					\
+		snprintf(cmd, sizeof(cmd), fmt, ##__VA_ARGS__);	\
+		if (!ASSERT_OK(system(cmd), cmd))		\
+			goto fail;				\
+	})
+
+struct udp_packet {
+	struct ethhdr eth;
+	struct ipv6hdr iph;
+	struct udphdr udp;
+	__u8 payload[64 - sizeof(struct udphdr)
+		     - sizeof(struct ethhdr) - sizeof(struct ipv6hdr)];
+} __packed;
+
+static struct udp_packet pkt_udp = {
+	.eth.h_proto = __bpf_constant_htons(ETH_P_IPV6),
+	.eth.h_dest = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55},
+	.eth.h_source = {0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb},
+	.iph.version = 6,
+	.iph.nexthdr = IPPROTO_UDP,
+	.iph.payload_len = bpf_htons(sizeof(struct udp_packet)
+				     - offsetof(struct udp_packet, udp)),
+	.iph.hop_limit = 2,
+	.iph.saddr.s6_addr16 = {bpf_htons(0xfc00), 0, 0, 0, 0, 0, 0, bpf_htons(1)},
+	.iph.daddr.s6_addr16 = {bpf_htons(0xfc00), 0, 0, 0, 0, 0, 0, bpf_htons(2)},
+	.udp.source = bpf_htons(1),
+	.udp.dest = bpf_htons(1),
+	.udp.len = bpf_htons(sizeof(struct udp_packet)
+			     - offsetof(struct udp_packet, udp)),
+	.payload = {0x42}, /* receiver XDP program matches on this */
+};
+
+#define NUM_PKTS 3
+void test_xdp_do_redirect(void)
+{
+	struct test_xdp_do_redirect *skel = NULL;
+	struct xdp_md ctx_in = { .data_end = sizeof(pkt_udp) };
+	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
+			    .data_in = &pkt_udp,
+			    .data_size_in = sizeof(pkt_udp),
+			    .ctx_in = &ctx_in,
+			    .ctx_size_in = sizeof(ctx_in),
+			    .flags = BPF_F_TEST_XDP_LIVE_FRAMES,
+			    .repeat = NUM_PKTS,
+		);
+	int err, prog_fd, ifindex_src, ifindex_dst;
+	struct bpf_link *link;
+
+	skel = test_xdp_do_redirect__open();
+	if (!ASSERT_OK_PTR(skel, "skel"))
+		return;
+
+	/* We setup a veth pair that we can not only XDP_REDIRECT packets
+	 * between, but also route them. The test packet (defined above) has
+	 * address information so it will be routed back out the same interface
+	 * after it has been received, which will allow it to be picked up by
+	 * the XDP program on the destination interface.
+	 *
+	 * The XDP program we run with bpf_prog_run() will cycle through all
+	 * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
+	 * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
+	 * the UDP payload.
+	 */
+	SYS("ip link add veth_src type veth peer name veth_dst");
+	SYS("ip link set dev veth_src address 00:11:22:33:44:55");
+	SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
+	SYS("ip link set dev veth_src up");
+	SYS("ip link set dev veth_dst up");
+	SYS("ip addr add dev veth_src fc00::1/64");
+	SYS("ip addr add dev veth_dst fc00::2/64");
+	SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
+	SYS("sysctl -w net.ipv6.conf.all.forwarding=1");
+
+	ifindex_src = if_nametoindex("veth_src");
+	ifindex_dst = if_nametoindex("veth_dst");
+	if (!ASSERT_NEQ(ifindex_src, 0, "ifindex_src") ||
+	    !ASSERT_NEQ(ifindex_dst, 0, "ifindex_dst"))
+		goto fail;
+
+	memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN);
+	skel->rodata->ifindex_out = ifindex_src;
+	ctx_in.ingress_ifindex = ifindex_src;
+
+	if (!ASSERT_OK(test_xdp_do_redirect__load(skel), "load"))
+		goto fail;
+
+	link = bpf_program__attach_xdp(skel->progs.xdp_count_pkts, ifindex_dst);
+	if (!ASSERT_OK_PTR(link, "prog_attach"))
+		goto fail;
+	skel->links.xdp_count_pkts = link;
+
+	prog_fd = bpf_program__fd(skel->progs.xdp_redirect_notouch);
+	err = bpf_prog_test_run_opts(prog_fd, &opts);
+	if (!ASSERT_OK(err, "prog_run"))
+		goto fail;
+
+	/* wait for the packets to be flushed */
+	kern_sync_rcu();
+
+	ASSERT_EQ(skel->bss->pkts_seen, NUM_PKTS - 1, "pkt_count");
+fail:
+	system("ip link del dev veth_src");
+	test_xdp_do_redirect__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c b/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c
new file mode 100644
index 000000000000..f9ea587b0876
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+#define ETH_ALEN 6
+const volatile int ifindex_out;
+const volatile __u8 expect_dst[ETH_ALEN];
+volatile int pkts_seen = 0;
+volatile int retcode = XDP_DROP;
+
+SEC("xdp")
+int xdp_redirect_notouch(struct xdp_md *xdp)
+{
+	if (retcode == XDP_REDIRECT)
+		bpf_redirect(ifindex_out, 0);
+	return retcode++;
+}
+
+SEC("xdp")
+int xdp_count_pkts(struct xdp_md *xdp)
+{
+	void *data = (void *)(long)xdp->data;
+	void *data_end = (void *)(long)xdp->data_end;
+	struct ethhdr *eth = data;
+	struct ipv6hdr *iph = (void *)(eth + 1);
+	struct udphdr *udp = (void *)(iph + 1);
+	__u8 *payload = (void *)(udp + 1);
+	int i;
+
+	if (payload + 1 > data_end)
+		return XDP_ABORTED;
+
+	if (iph->nexthdr == IPPROTO_UDP && *payload == 0x42)
+		pkts_seen++;
+
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.34.1

Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Alexei Starovoitov]

On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke Høiland-Jørgensen wrote:
> +
> +#define NUM_PKTS 3

May be send a bit more than 3 packets?
Just to test skb_list logic for XDP_PASS.

> +
> +	/* We setup a veth pair that we can not only XDP_REDIRECT packets
> +	 * between, but also route them. The test packet (defined above) has
> +	 * address information so it will be routed back out the same interface
> +	 * after it has been received, which will allow it to be picked up by
> +	 * the XDP program on the destination interface.
> +	 *
> +	 * The XDP program we run with bpf_prog_run() will cycle through all
> +	 * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
> +	 * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
> +	 * the UDP payload.
> +	 */
> +	SYS("ip link add veth_src type veth peer name veth_dst");
> +	SYS("ip link set dev veth_src address 00:11:22:33:44:55");
> +	SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
> +	SYS("ip link set dev veth_src up");
> +	SYS("ip link set dev veth_dst up");
> +	SYS("ip addr add dev veth_src fc00::1/64");
> +	SYS("ip addr add dev veth_dst fc00::2/64");
> +	SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
> +	SYS("sysctl -w net.ipv6.conf.all.forwarding=1");

These commands pollute current netns. The test has to create its own netns
like other tests do.

The forwarding=1 is odd. Nothing in the comments or commit logs
talks about it.
I'm guessing it's due to patch 6 limitation of picking loopback
for XDP_PASS and XDP_TX, right?
There is ingress_ifindex field in struct xdp_md.
May be use that to setup dev and rxq in test_run in patch 6?
Then there will be no need to hack through forwarding=1 ?

Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Toke Høiland-Jørgensen]

Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:

> On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke Høiland-Jørgensen wrote:
>> +
>> +#define NUM_PKTS 3
>
> May be send a bit more than 3 packets?
> Just to test skb_list logic for XDP_PASS.

OK, can do.

>> +
>> +	/* We setup a veth pair that we can not only XDP_REDIRECT packets
>> +	 * between, but also route them. The test packet (defined above) has
>> +	 * address information so it will be routed back out the same interface
>> +	 * after it has been received, which will allow it to be picked up by
>> +	 * the XDP program on the destination interface.
>> +	 *
>> +	 * The XDP program we run with bpf_prog_run() will cycle through all
>> +	 * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
>> +	 * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
>> +	 * the UDP payload.
>> +	 */
>> +	SYS("ip link add veth_src type veth peer name veth_dst");
>> +	SYS("ip link set dev veth_src address 00:11:22:33:44:55");
>> +	SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
>> +	SYS("ip link set dev veth_src up");
>> +	SYS("ip link set dev veth_dst up");
>> +	SYS("ip addr add dev veth_src fc00::1/64");
>> +	SYS("ip addr add dev veth_dst fc00::2/64");
>> +	SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
>> +	SYS("sysctl -w net.ipv6.conf.all.forwarding=1");
>
> These commands pollute current netns. The test has to create its own netns
> like other tests do.

Right, will fix.

> The forwarding=1 is odd. Nothing in the comments or commit logs
> talks about it.

Hmm, yeah, should probably have added an explanation, sorry about that :)

> I'm guessing it's due to patch 6 limitation of picking loopback
> for XDP_PASS and XDP_TX, right?
> There is ingress_ifindex field in struct xdp_md.
> May be use that to setup dev and rxq in test_run in patch 6?
> Then there will be no need to hack through forwarding=1 ?

No, as you note there's already ingress_ifindex to set the device, and
the test does use that:

+	memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN);
+	skel->rodata->ifindex_out = ifindex_src;
+	ctx_in.ingress_ifindex = ifindex_src;

I enable forwarding because the XDP program that counts the packets is
running on the other end of the veth pair (on veth_dst), while the
traffic gen is using veth_src as its ingress ifindex. So for XDP_TX and
XDP_REDIRECT we send the frame back out the veth device, and it ends up
being processed by the XDP program on veth_dst, and counted. But when
the test program returns XDP_PASS, the packet will go up the frame; so
to get it back to the counting program I enable forwarding and set the
packet dst IP so that the stack routes it back out the same interface.

I'll admit this is a bit hacky; I guess I can add a second TC ingress
program that will count the packets being XDP_PASS'ed instead...

-Toke

Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Alexei Starovoitov]

On Thu, Jan 6, 2022 at 6:34 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
>
> > On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke Høiland-Jørgensen wrote:
> >> +
> >> +#define NUM_PKTS 3
> >
> > May be send a bit more than 3 packets?
> > Just to test skb_list logic for XDP_PASS.
>
> OK, can do.
>
> >> +
> >> +    /* We setup a veth pair that we can not only XDP_REDIRECT packets
> >> +     * between, but also route them. The test packet (defined above) has
> >> +     * address information so it will be routed back out the same interface
> >> +     * after it has been received, which will allow it to be picked up by
> >> +     * the XDP program on the destination interface.
> >> +     *
> >> +     * The XDP program we run with bpf_prog_run() will cycle through all
> >> +     * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
> >> +     * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
> >> +     * the UDP payload.
> >> +     */
> >> +    SYS("ip link add veth_src type veth peer name veth_dst");
> >> +    SYS("ip link set dev veth_src address 00:11:22:33:44:55");
> >> +    SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
> >> +    SYS("ip link set dev veth_src up");
> >> +    SYS("ip link set dev veth_dst up");
> >> +    SYS("ip addr add dev veth_src fc00::1/64");
> >> +    SYS("ip addr add dev veth_dst fc00::2/64");
> >> +    SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
> >> +    SYS("sysctl -w net.ipv6.conf.all.forwarding=1");
> >
> > These commands pollute current netns. The test has to create its own netns
> > like other tests do.
>
> Right, will fix.
>
> > The forwarding=1 is odd. Nothing in the comments or commit logs
> > talks about it.
>
> Hmm, yeah, should probably have added an explanation, sorry about that :)
>
> > I'm guessing it's due to patch 6 limitation of picking loopback
> > for XDP_PASS and XDP_TX, right?
> > There is ingress_ifindex field in struct xdp_md.
> > May be use that to setup dev and rxq in test_run in patch 6?
> > Then there will be no need to hack through forwarding=1 ?
>
> No, as you note there's already ingress_ifindex to set the device, and
> the test does use that:
>
> +       memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN);
> +       skel->rodata->ifindex_out = ifindex_src;
> +       ctx_in.ingress_ifindex = ifindex_src;

My point is that this ingress_ifindex should be used instead of loopback.
Otherwise the test_run infra is lying to the xdp program.

> I enable forwarding because the XDP program that counts the packets is
> running on the other end of the veth pair (on veth_dst), while the
> traffic gen is using veth_src as its ingress ifindex. So for XDP_TX and
> XDP_REDIRECT we send the frame back out the veth device, and it ends up
> being processed by the XDP program on veth_dst, and counted.

Not for XDP_TX. If I'm reading patch 6 correctly it gets xmited
out of loopback.

> But when
> the test program returns XDP_PASS, the packet will go up the frame; so
> to get it back to the counting program I enable forwarding and set the
> packet dst IP so that the stack routes it back out the same interface.
>
> I'll admit this is a bit hacky; I guess I can add a second TC ingress
> program that will count the packets being XDP_PASS'ed instead...

No. Please figure out how to XDP_PASS and XDP_TX without enabling forward
and counting in different places.
imo the forwarding hides the issue in the design that should be addressed.
When rx ifindex is an actual ifindex given by user space instead of
loopback all problems go away.

Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Toke Høiland-Jørgensen]

Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:

> On Thu, Jan 6, 2022 at 6:34 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
>>
>> > On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke Høiland-Jørgensen wrote:
>> >> +
>> >> +#define NUM_PKTS 3
>> >
>> > May be send a bit more than 3 packets?
>> > Just to test skb_list logic for XDP_PASS.
>>
>> OK, can do.
>>
>> >> +
>> >> +    /* We setup a veth pair that we can not only XDP_REDIRECT packets
>> >> +     * between, but also route them. The test packet (defined above) has
>> >> +     * address information so it will be routed back out the same interface
>> >> +     * after it has been received, which will allow it to be picked up by
>> >> +     * the XDP program on the destination interface.
>> >> +     *
>> >> +     * The XDP program we run with bpf_prog_run() will cycle through all
>> >> +     * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
>> >> +     * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
>> >> +     * the UDP payload.
>> >> +     */
>> >> +    SYS("ip link add veth_src type veth peer name veth_dst");
>> >> +    SYS("ip link set dev veth_src address 00:11:22:33:44:55");
>> >> +    SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
>> >> +    SYS("ip link set dev veth_src up");
>> >> +    SYS("ip link set dev veth_dst up");
>> >> +    SYS("ip addr add dev veth_src fc00::1/64");
>> >> +    SYS("ip addr add dev veth_dst fc00::2/64");
>> >> +    SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
>> >> +    SYS("sysctl -w net.ipv6.conf.all.forwarding=1");
>> >
>> > These commands pollute current netns. The test has to create its own netns
>> > like other tests do.
>>
>> Right, will fix.
>>
>> > The forwarding=1 is odd. Nothing in the comments or commit logs
>> > talks about it.
>>
>> Hmm, yeah, should probably have added an explanation, sorry about that :)
>>
>> > I'm guessing it's due to patch 6 limitation of picking loopback
>> > for XDP_PASS and XDP_TX, right?
>> > There is ingress_ifindex field in struct xdp_md.
>> > May be use that to setup dev and rxq in test_run in patch 6?
>> > Then there will be no need to hack through forwarding=1 ?
>>
>> No, as you note there's already ingress_ifindex to set the device, and
>> the test does use that:
>>
>> +       memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN);
>> +       skel->rodata->ifindex_out = ifindex_src;
>> +       ctx_in.ingress_ifindex = ifindex_src;
>
> My point is that this ingress_ifindex should be used instead of loopback.
> Otherwise the test_run infra is lying to the xdp program.

But it is already using that! There is just no explicit code in patch 6
to do that because that was already part of the XDP prog_run
functionality.

Specifically, the existing bpf_prog_test_run_xdp() will pass the context
through xdp_convert_md_to_buff() which will resolve the ifindex and get
a dev reference. So the xdp_buff object being passed to the new
bpf_test_run_xdp_live() function already has the right device in
ctx->rxq.

I'll add a check for this to the selftest to make it explicit.

>> I enable forwarding because the XDP program that counts the packets is
>> running on the other end of the veth pair (on veth_dst), while the
>> traffic gen is using veth_src as its ingress ifindex. So for XDP_TX and
>> XDP_REDIRECT we send the frame back out the veth device, and it ends up
>> being processed by the XDP program on veth_dst, and counted.
>
> Not for XDP_TX. If I'm reading patch 6 correctly it gets xmited
> out of loopback.

See above.

>> But when
>> the test program returns XDP_PASS, the packet will go up the frame; so
>> to get it back to the counting program I enable forwarding and set the
>> packet dst IP so that the stack routes it back out the same interface.
>>
>> I'll admit this is a bit hacky; I guess I can add a second TC ingress
>> program that will count the packets being XDP_PASS'ed instead...
>
> No. Please figure out how to XDP_PASS and XDP_TX without enabling forward
> and counting in different places.
> imo the forwarding hides the issue in the design that should be addressed.
> When rx ifindex is an actual ifindex given by user space instead of
> loopback all problems go away.

No the problem of XDP_PASS going in the opposite direction of XDP_TX and
XDP_REDIRECT remains. This is just like on a physical interface: if you
XDP_TX a packet it goes back out, if you XDP_PASS it, it goes up the
stack. To intercept both after the fact, you need to look in two
different places.

Anyhow, just using a TC hook for XDP_PASS works fine and gets rid of the
forwarding hack; I'll send a v6 with that just as soon as I verify that
I didn't break anything when running the traffic generator on bare metal :)

-Toke

Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Alexei Starovoitov]

On Thu, Jan 6, 2022 at 10:21 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
>
> > On Thu, Jan 6, 2022 at 6:34 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >>
> >> Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
> >>
> >> > On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke Høiland-Jørgensen wrote:
> >> >> +
> >> >> +#define NUM_PKTS 3
> >> >
> >> > May be send a bit more than 3 packets?
> >> > Just to test skb_list logic for XDP_PASS.
> >>
> >> OK, can do.
> >>
> >> >> +
> >> >> +    /* We setup a veth pair that we can not only XDP_REDIRECT packets
> >> >> +     * between, but also route them. The test packet (defined above) has
> >> >> +     * address information so it will be routed back out the same interface
> >> >> +     * after it has been received, which will allow it to be picked up by
> >> >> +     * the XDP program on the destination interface.
> >> >> +     *
> >> >> +     * The XDP program we run with bpf_prog_run() will cycle through all
> >> >> +     * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
> >> >> +     * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
> >> >> +     * the UDP payload.
> >> >> +     */
> >> >> +    SYS("ip link add veth_src type veth peer name veth_dst");
> >> >> +    SYS("ip link set dev veth_src address 00:11:22:33:44:55");
> >> >> +    SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
> >> >> +    SYS("ip link set dev veth_src up");
> >> >> +    SYS("ip link set dev veth_dst up");
> >> >> +    SYS("ip addr add dev veth_src fc00::1/64");
> >> >> +    SYS("ip addr add dev veth_dst fc00::2/64");
> >> >> +    SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
> >> >> +    SYS("sysctl -w net.ipv6.conf.all.forwarding=1");
> >> >
> >> > These commands pollute current netns. The test has to create its own netns
> >> > like other tests do.
> >>
> >> Right, will fix.
> >>
> >> > The forwarding=1 is odd. Nothing in the comments or commit logs
> >> > talks about it.
> >>
> >> Hmm, yeah, should probably have added an explanation, sorry about that :)
> >>
> >> > I'm guessing it's due to patch 6 limitation of picking loopback
> >> > for XDP_PASS and XDP_TX, right?
> >> > There is ingress_ifindex field in struct xdp_md.
> >> > May be use that to setup dev and rxq in test_run in patch 6?
> >> > Then there will be no need to hack through forwarding=1 ?
> >>
> >> No, as you note there's already ingress_ifindex to set the device, and
> >> the test does use that:
> >>
> >> +       memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN);
> >> +       skel->rodata->ifindex_out = ifindex_src;
> >> +       ctx_in.ingress_ifindex = ifindex_src;
> >
> > My point is that this ingress_ifindex should be used instead of loopback.
> > Otherwise the test_run infra is lying to the xdp program.
>
> But it is already using that! There is just no explicit code in patch 6
> to do that because that was already part of the XDP prog_run
> functionality.
>
> Specifically, the existing bpf_prog_test_run_xdp() will pass the context
> through xdp_convert_md_to_buff() which will resolve the ifindex and get
> a dev reference. So the xdp_buff object being passed to the new
> bpf_test_run_xdp_live() function already has the right device in
> ctx->rxq.

Got it. Please make it clear in the commit log.

> No the problem of XDP_PASS going in the opposite direction of XDP_TX and
> XDP_REDIRECT remains. This is just like on a physical interface: if you
> XDP_TX a packet it goes back out, if you XDP_PASS it, it goes up the
> stack. To intercept both after the fact, you need to look in two
> different places.
>
> Anyhow, just using a TC hook for XDP_PASS works fine and gets rid of the
> forwarding hack; I'll send a v6 with that just as soon as I verify that
> I didn't break anything when running the traffic generator on bare metal :)

Got it. You mean a tc ingress prog attached to veth_src ? That should work.

Re: [PATCH bpf-next v5 7/7] selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()

[Toke Høiland-Jørgensen]

Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:

> On Thu, Jan 6, 2022 at 10:21 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
>>
>> > On Thu, Jan 6, 2022 at 6:34 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>> >>
>> >> Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:
>> >>
>> >> > On Mon, Jan 03, 2022 at 04:08:12PM +0100, Toke Høiland-Jørgensen wrote:
>> >> >> +
>> >> >> +#define NUM_PKTS 3
>> >> >
>> >> > May be send a bit more than 3 packets?
>> >> > Just to test skb_list logic for XDP_PASS.
>> >>
>> >> OK, can do.
>> >>
>> >> >> +
>> >> >> +    /* We setup a veth pair that we can not only XDP_REDIRECT packets
>> >> >> +     * between, but also route them. The test packet (defined above) has
>> >> >> +     * address information so it will be routed back out the same interface
>> >> >> +     * after it has been received, which will allow it to be picked up by
>> >> >> +     * the XDP program on the destination interface.
>> >> >> +     *
>> >> >> +     * The XDP program we run with bpf_prog_run() will cycle through all
>> >> >> +     * four return codes (DROP/PASS/TX/REDIRECT), so we should end up with
>> >> >> +     * NUM_PKTS - 1 packets seen on the dst iface. We match the packets on
>> >> >> +     * the UDP payload.
>> >> >> +     */
>> >> >> +    SYS("ip link add veth_src type veth peer name veth_dst");
>> >> >> +    SYS("ip link set dev veth_src address 00:11:22:33:44:55");
>> >> >> +    SYS("ip link set dev veth_dst address 66:77:88:99:aa:bb");
>> >> >> +    SYS("ip link set dev veth_src up");
>> >> >> +    SYS("ip link set dev veth_dst up");
>> >> >> +    SYS("ip addr add dev veth_src fc00::1/64");
>> >> >> +    SYS("ip addr add dev veth_dst fc00::2/64");
>> >> >> +    SYS("ip neigh add fc00::2 dev veth_src lladdr 66:77:88:99:aa:bb");
>> >> >> +    SYS("sysctl -w net.ipv6.conf.all.forwarding=1");
>> >> >
>> >> > These commands pollute current netns. The test has to create its own netns
>> >> > like other tests do.
>> >>
>> >> Right, will fix.
>> >>
>> >> > The forwarding=1 is odd. Nothing in the comments or commit logs
>> >> > talks about it.
>> >>
>> >> Hmm, yeah, should probably have added an explanation, sorry about that :)
>> >>
>> >> > I'm guessing it's due to patch 6 limitation of picking loopback
>> >> > for XDP_PASS and XDP_TX, right?
>> >> > There is ingress_ifindex field in struct xdp_md.
>> >> > May be use that to setup dev and rxq in test_run in patch 6?
>> >> > Then there will be no need to hack through forwarding=1 ?
>> >>
>> >> No, as you note there's already ingress_ifindex to set the device, and
>> >> the test does use that:
>> >>
>> >> +       memcpy(skel->rodata->expect_dst, &pkt_udp.eth.h_dest, ETH_ALEN);
>> >> +       skel->rodata->ifindex_out = ifindex_src;
>> >> +       ctx_in.ingress_ifindex = ifindex_src;
>> >
>> > My point is that this ingress_ifindex should be used instead of loopback.
>> > Otherwise the test_run infra is lying to the xdp program.
>>
>> But it is already using that! There is just no explicit code in patch 6
>> to do that because that was already part of the XDP prog_run
>> functionality.
>>
>> Specifically, the existing bpf_prog_test_run_xdp() will pass the context
>> through xdp_convert_md_to_buff() which will resolve the ifindex and get
>> a dev reference. So the xdp_buff object being passed to the new
>> bpf_test_run_xdp_live() function already has the right device in
>> ctx->rxq.
>
> Got it. Please make it clear in the commit log.

Ah, sorry, already hit send on v6 before I saw this. If you want to fix
up the commit message while applying, how about a paragraph at the end
like:


The new mode reuses the setup code from the existing bpf_prog_run() for
XDP. This means that userspace can set the ingress ifindex and RXQ
number as part of the context object being passed to the kernel, in
which case packets will look like they arrived on that interface when
the test program returns XDP_PASS and the packets go up the stack.

>> No the problem of XDP_PASS going in the opposite direction of XDP_TX and
>> XDP_REDIRECT remains. This is just like on a physical interface: if you
>> XDP_TX a packet it goes back out, if you XDP_PASS it, it goes up the
>> stack. To intercept both after the fact, you need to look in two
>> different places.
>>
>> Anyhow, just using a TC hook for XDP_PASS works fine and gets rid of the
>> forwarding hack; I'll send a v6 with that just as soon as I verify that
>> I didn't break anything when running the traffic generator on bare metal :)
>
> Got it. You mean a tc ingress prog attached to veth_src ? That should work.

Yup, exactly!

-Toke