From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:41:32
This series introduce XDP multi-buffer support. The mvneta driver is
the first to support these new "non-linear" xdp_{buff,frame}. Reviewers
please focus on how these new types of xdp_{buff,frame} packets
traverse the different layers and the layout design. It is on purpose
that BPF-helpers are kept simple, as we don't want to expose the
internal layout to allow later changes.
The main idea for the new multi-buffer layout is to reuse the same
structure used for non-linear SKB. This rely on the "skb_shared_info"
struct at the end of the first buffer to link together subsequent
buffers. Keeping the layout compatible with SKBs is also done to ease
and speedup creating a SKB from an xdp_{buff,frame}.
Converting xdp_frame to SKB and deliver it to the network stack is shown
in patch 05/18 (e.g. cpumaps).
A multi-buffer bit (mb) has been introduced in the flags field of xdp_{buff,frame}
structure to notify the bpf/network layer if this is a xdp multi-buffer frame
(mb = 1) or not (mb = 0).
The mb bit will be set by a xdp multi-buffer capable driver only for
non-linear frames maintaining the capability to receive linear frames
without any extra cost since the skb_shared_info structure at the end
of the first buffer will be initialized only if mb is set.
Moreover the flags field in xdp_{buff,frame} will be reused even for
xdp rx csum offloading in future series.
Typical use cases for this series are:
- Jumbo-frames
- Packet header split (please see Googleâs use-case @ NetDevConf 0x14, [0])
- TSO/GRO
The two following ebpf helpers (and related selftests) has been introduced:
- bpf_xdp_adjust_data:
Move xdp_md->data and xdp_md->data_end pointers in subsequent fragments
according to the offset provided by the ebpf program. This helper can be
used to read/write values in frame payload.
- bpf_xdp_get_buff_len:
Return the total frame size (linear + paged parts)
bpf_xdp_adjust_tail and bpf_xdp_copy helpers have been modified to take into
account xdp multi-buff frames.
More info about the main idea behind this approach can be found here [1][2].
Changes since v11:
- add missing static to bpf_xdp_get_buff_len_proto structure
- fix bpf_xdp_adjust_data helper when offset is smaller than linear area length.
Changes since v10:
- move xdp->data to the requested payload offset instead of to the beginning of
the fragment in bpf_xdp_adjust_data()
Changes since v9:
- introduce bpf_xdp_adjust_data helper and related selftest
- add xdp_frags_size and xdp_frags_tsize fields in skb_shared_info
- introduce xdp_update_skb_shared_info utility routine in ordere to not reset
frags array in skb_shared_info converting from a xdp_buff/xdp_frame to a skb
- simplify bpf_xdp_copy routine
Changes since v8:
- add proper dma unmapping if XDP_TX fails on mvneta for a xdp multi-buff
- switch back to skb_shared_info implementation from previous xdp_shared_info
one
- avoid using a bietfield in xdp_buff/xdp_frame since it introduces performance
regressions. Tested now on 10G NIC (ixgbe) to verify there are no performance
penalties for regular codebase
- add bpf_xdp_get_buff_len helper and remove frame_length field in xdp ctx
- add data_len field in skb_shared_info struct
- introduce XDP_FLAGS_FRAGS_PF_MEMALLOC flag
Changes since v7:
- rebase on top of bpf-next
- fix sparse warnings
- improve comments for frame_length in include/net/xdp.h
Changes since v6:
- the main difference respect to previous versions is the new approach proposed
by Eelco to pass full length of the packet to eBPF layer in XDP context
- reintroduce multi-buff support to eBPF kself-tests
- reintroduce multi-buff support to bpf_xdp_adjust_tail helper
- introduce multi-buffer support to bpf_xdp_copy helper
- rebase on top of bpf-next
Changes since v5:
- rebase on top of bpf-next
- initialize mb bit in xdp_init_buff() and drop per-driver initialization
- drop xdp->mb initialization in xdp_convert_zc_to_xdp_frame()
- postpone introduction of frame_length field in XDP ctx to another series
- minor changes
Changes since v4:
- rebase ontop of bpf-next
- introduce xdp_shared_info to build xdp multi-buff instead of using the
skb_shared_info struct
- introduce frame_length in xdp ctx
- drop previous bpf helpers
- fix bpf_xdp_adjust_tail for xdp multi-buff
- introduce xdp multi-buff self-tests for bpf_xdp_adjust_tail
- fix xdp_return_frame_bulk for xdp multi-buff
Changes since v3:
- rebase ontop of bpf-next
- add patch 10/13 to copy back paged data from a xdp multi-buff frame to
userspace buffer for xdp multi-buff selftests
Changes since v2:
- add throughput measurements
- drop bpf_xdp_adjust_mb_header bpf helper
- introduce selftest for xdp multibuffer
- addressed comments on bpf_xdp_get_frags_count
- introduce xdp multi-buff support to cpumaps
Changes since v1:
- Fix use-after-free in xdp_return_{buff/frame}
- Introduce bpf helpers
- Introduce xdp_mb sample program
- access skb_shared_info->nr_frags only on the last fragment
Changes since RFC:
- squash multi-buffer bit initialization in a single patch
- add mvneta non-linear XDP buff support for tx side
[0] https://netdevconf.info/0x14/session.html?talk-the-path-to-tcp-4k-mtu-and-rx-zerocopy
[1] https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org
[2] https://netdevconf.info/0x14/session.html?tutorial-add-XDP-support-to-a-NIC-driver (XDPmulti-buffers section)
Eelco Chaudron (3):
bpf: add multi-buff support to the bpf_xdp_adjust_tail() API
bpf: add multi-buffer support to xdp copy helpers
bpf: update xdp_adjust_tail selftest to include multi-buffer
Lorenzo Bianconi (15):
net: skbuff: add size metadata to skb_shared_info for xdp
xdp: introduce flags field in xdp_buff/xdp_frame
net: mvneta: update mb bit before passing the xdp buffer to eBPF layer
net: mvneta: simplify mvneta_swbm_add_rx_fragment management
net: xdp: add xdp_update_skb_shared_info utility routine
net: marvell: rely on xdp_update_skb_shared_info utility routine
xdp: add multi-buff support to xdp_return_{buff/frame}
net: mvneta: add multi buffer support to XDP_TX
net: mvneta: enable jumbo frames for XDP
bpf: introduce bpf_xdp_get_buff_len helper
bpf: move user_size out of bpf_test_init
bpf: introduce multibuff support to bpf_prog_test_run_xdp()
bpf: test_run: add xdp_shared_info pointer in bpf_test_finish
signature
net: xdp: introduce bpf_xdp_adjust_data helper
bpf: add bpf_xdp_adjust_data selftest
drivers/net/ethernet/marvell/mvneta.c | 204 ++++++++++-------
include/linux/skbuff.h | 6 +-
include/net/xdp.h | 95 +++++++-
include/uapi/linux/bpf.h | 39 ++++
kernel/trace/bpf_trace.c | 3 +
net/bpf/test_run.c | 117 ++++++++--
net/core/filter.c | 213 +++++++++++++++++-
net/core/xdp.c | 76 ++++++-
tools/include/uapi/linux/bpf.h | 39 ++++
.../bpf/prog_tests/xdp_adjust_data.c | 55 +++++
.../bpf/prog_tests/xdp_adjust_tail.c | 118 ++++++++++
.../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 151 +++++++++----
.../bpf/progs/test_xdp_adjust_tail_grow.c | 10 +-
.../bpf/progs/test_xdp_adjust_tail_shrink.c | 32 ++-
.../selftests/bpf/progs/test_xdp_bpf2bpf.c | 2 +-
.../bpf/progs/test_xdp_update_frags.c | 41 ++++
16 files changed, 1036 insertions(+), 165 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_adjust_data.c
create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_update_frags.c
--
2.31.1
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:42:34
Introduce xdp_frags_tsize field in skb_shared_info data structure
to store xdp_buff/xdp_frame truesize (xdp_frags_tsize will be used
in xdp multi-buff support). In order to not increase skb_shared_info
size we will use a hole due to skb_shared_info alignment.
Introduce xdp_frags_size field in skb_shared_info data structure
reusing gso_type field in order to store xdp_buff/xdp_frame paged size.
xdp_frags_size will be used in xdp multi-buff support.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/linux/skbuff.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:42:49
Introduce flags field in xdp_frame and xdp_buffer data structures
to define additional buffer features. At the moment the only
supported buffer feature is multi-buffer bit (mb). Multi-buffer bit
is used to specify if this is a linear buffer (mb = 0) or a multi-buffer
frame (mb = 1). In the latter case the driver is expected to initialize
the skb_shared_info structure at the end of the first buffer to link
together subsequent buffers belonging to the same frame.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/net/xdp.h | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
@@ -74,13 +78,30 @@ struct xdp_buff {structxdp_rxq_info*rxq;structxdp_txq_info*txq;u32frame_sz;/* frame size to deduce data_hard_end/reserved tailroom*/+u16flags;/* supported values defined in xdp_flags */};+static__always_inlineboolxdp_buff_is_mb(structxdp_buff*xdp)+{+return!!(xdp->flags&XDP_FLAGS_MULTI_BUFF);+}++static__always_inlinevoidxdp_buff_set_mb(structxdp_buff*xdp)+{+xdp->flags|=XDP_FLAGS_MULTI_BUFF;+}++static__always_inlinevoidxdp_buff_clear_mb(structxdp_buff*xdp)+{+xdp->flags&=~XDP_FLAGS_MULTI_BUFF;+}+static__always_inlinevoidxdp_init_buff(structxdp_buff*xdp,u32frame_sz,structxdp_rxq_info*rxq){xdp->frame_sz=frame_sz;xdp->rxq=rxq;+xdp->flags=0;}static__always_inlinevoid
@@ -122,8 +143,14 @@ struct xdp_frame {*/structxdp_mem_infomem;structnet_device*dev_rx;/* used by cpumap */+u16flags;/* supported values defined in xdp_flags */};+static__always_inlineboolxdp_frame_is_mb(structxdp_frame*frame)+{+return!!(frame->flags&XDP_FLAGS_MULTI_BUFF);+}+#define XDP_BULK_QUEUE_SIZE 16structxdp_frame_bulk{intcount;
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:42:59
Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and
XDP remote drivers if this is a "non-linear" XDP buffer. Access
skb_shared_info only if xdp_buff mb is set in order to avoid possible
cache-misses.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:02
Relying on xdp mb bit, remove skb_shared_info structure allocated on the
stack in mvneta_rx_swbm routine and simplify mvneta_swbm_add_rx_fragment
accessing skb_shared_info in the xdp_buff structure directly. There is no
performance penalty in this approach since mvneta_swbm_add_rx_fragment
is run just for multi-buff use-case.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 42 ++++++++++-----------------
1 file changed, 15 insertions(+), 27 deletions(-)
@@ -2307,16 +2309,6 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,}else{page_pool_put_full_page(rxq->page_pool,page,true);}--/* last fragment */-if(len==*size){-structskb_shared_info*sinfo;--sinfo=xdp_get_shared_info_from_buff(xdp);-sinfo->nr_frags=xdp_sinfo->nr_frags;-memcpy(sinfo->frags,xdp_sinfo->frags,-sinfo->nr_frags*sizeof(skb_frag_t));-}*size-=len;}
@@ -2364,7 +2356,6 @@ static int mvneta_rx_swbm(struct napi_struct *napi,{intrx_proc=0,rx_todo,refill,size=0;structnet_device*dev=pp->dev;-structskb_shared_infosinfo;structmvneta_statsps={};structbpf_prog*xdp_prog;u32desc_status,frame_sz;
@@ -2373,8 +2364,6 @@ static int mvneta_rx_swbm(struct napi_struct *napi,xdp_init_buff(&xdp_buf,PAGE_SIZE,&rxq->xdp_rxq);xdp_buf.data_hard_start=NULL;-sinfo.nr_frags=0;-/* Get number of received packets */rx_todo=mvneta_rxq_busy_desc_num_get(pp,rxq);
@@ -2416,7 +2405,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,}mvneta_swbm_add_rx_fragment(pp,rx_desc,rxq,&xdp_buf,-&size,&sinfo,page);+&size,page);}/* Middle or Last descriptor */if(!(rx_status&MVNETA_RXD_LAST_DESC))
@@ -2424,7 +2413,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,continue;if(size){-mvneta_xdp_put_buff(pp,rxq,&xdp_buf,&sinfo,-1);+mvneta_xdp_put_buff(pp,rxq,&xdp_buf,-1);gotonext;}
@@ -2436,7 +2425,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,if(IS_ERR(skb)){structmvneta_pcpu_stats*stats=this_cpu_ptr(pp->stats);-mvneta_xdp_put_buff(pp,rxq,&xdp_buf,&sinfo,-1);+mvneta_xdp_put_buff(pp,rxq,&xdp_buf,-1);u64_stats_update_begin(&stats->syncp);stats->es.skb_alloc_error++;
@@ -2453,11 +2442,10 @@ static int mvneta_rx_swbm(struct napi_struct *napi,napi_gro_receive(napi,skb);next:xdp_buf.data_hard_start=NULL;-sinfo.nr_frags=0;}if(xdp_buf.data_hard_start)-mvneta_xdp_put_buff(pp,rxq,&xdp_buf,&sinfo,-1);+mvneta_xdp_put_buff(pp,rxq,&xdp_buf,-1);if(ps.xdp_redirect)xdp_do_flush_map();
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:10
Introduce xdp_update_skb_shared_info routine to update frags array
metadata in skb_shared_info data structure converting to a skb from
a xdp_buff or xdp_frame.
According to the current skb_shared_info architecture in
xdp_frame/xdp_buff and to the xdp multi-buff support, there is
no need to run skb_add_rx_frag() and reset frags array converting the buffer
to a skb since the frag array will be in the same position for xdp_buff/xdp_frame
and for the skb, we just need to update memory metadata.
Introduce XDP_FLAGS_PF_MEMALLOC flag in xdp_buff_flags in order to mark
the xdp_buff or xdp_frame as under memory-pressure if pages of the frags array
are under memory pressure. Doing so we can avoid looping over all fragments in
xdp_update_skb_shared_info routine. The driver is expected to set the
flag constructing the xdp_buffer using xdp_buff_set_frag_pfmemalloc
utility routine.
Rely on xdp_update_skb_shared_info in __xdp_build_skb_from_frame routine
converting the multi-buff xdp_frame to a skb after performing a XDP_REDIRECT.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/net/xdp.h | 33 ++++++++++++++++++++++++++++++++-
net/core/xdp.c | 17 +++++++++++++++++
2 files changed, 49 insertions(+), 1 deletion(-)
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:11
Rely on xdp_update_skb_shared_info routine in order to avoid
resetting frags array in skb_shared_info structure building
the skb in mvneta_swbm_build_skb(). Frags array is expected to
be initialized by the receiving driver building the xdp_buff
and here we just need to update memory metadata.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 35 +++++++++++++++------------
1 file changed, 20 insertions(+), 15 deletions(-)
@@ -2304,11 +2304,19 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,skb_frag_size_set(frag,data_len);__skb_frag_set_page(frag,page);-if(!xdp_buff_is_mb(xdp))+if(!xdp_buff_is_mb(xdp)){+sinfo->xdp_frags_size=*size;xdp_buff_set_mb(xdp);+}+if(page_is_pfmemalloc(page))+xdp_buff_set_frag_pfmemalloc(xdp);}else{page_pool_put_full_page(rxq->page_pool,page,true);}++/* last fragment */+if(len==*size)+sinfo->xdp_frags_tsize=sinfo->nr_frags*PAGE_SIZE;*size-=len;}
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:13
Take into account if the received xdp_buff/xdp_frame is non-linear
recycling/returning the frame memory to the allocator or into
xdp_frame_bulk.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/net/xdp.h | 18 ++++++++++++++--
net/core/xdp.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 69 insertions(+), 3 deletions(-)
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:34
Enable the capability to receive jumbo frames even if the interface is
running in XDP mode
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 10 ----------
1 file changed, 10 deletions(-)
@@ -3767,11 +3767,6 @@ static int mvneta_change_mtu(struct net_device *dev, int mtu)mtu=ALIGN(MVNETA_RX_PKT_SIZE(mtu),8);}-if(pp->xdp_prog&&mtu>MVNETA_MAX_RX_BUF_SIZE){-netdev_info(dev,"Illegal MTU value %d for XDP mode\n",mtu);-return-EINVAL;-}-dev->mtu=mtu;if(!netif_running(dev)){
@@ -4481,11 +4476,6 @@ static int mvneta_xdp_setup(struct net_device *dev, struct bpf_prog *prog,structmvneta_port*pp=netdev_priv(dev);structbpf_prog*old_prog;-if(prog&&dev->mtu>MVNETA_MAX_RX_BUF_SIZE){-NL_SET_ERR_MSG_MOD(extack,"MTU too large for XDP");-return-EOPNOTSUPP;-}-if(pp->bm_priv){NL_SET_ERR_MSG_MOD(extack,"Hardware Buffer Management not supported on XDP");
@@ -4871,6 +4871,12 @@ union bpf_attr {*Return*ValuespecifiedbyuseratBPFlinkcreation/attachmenttime*or0,ifitwasnotspecified.+*+*u64bpf_xdp_get_buff_len(structxdp_buff*xdp_md)+*Description+*Getthetotalsizeofagivenxdpbuff(linearandpagedarea)+*Return+*Thetotalsizeofagivenxdpbuffer.*/#define __BPF_FUNC_MAPPER(FN) \FN(unspec),\
@@ -5048,6 +5054,7 @@ union bpf_attr {FN(timer_cancel),\FN(get_func_ip),\FN(get_attach_cookie),\+FN(xdp_get_buff_len),\/* *//* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -4871,6 +4871,12 @@ union bpf_attr {*Return*ValuespecifiedbyuseratBPFlinkcreation/attachmenttime*or0,ifitwasnotspecified.+*+*u64bpf_xdp_get_buff_len(structxdp_buff*xdp_md)+*Description+*Getthetotalsizeofagivenxdpbuff(linearandpagedarea)+*Return+*Thetotalsizeofagivenxdpbuffer.*/#define __BPF_FUNC_MAPPER(FN) \FN(unspec),\
@@ -5048,6 +5054,7 @@ union bpf_attr {FN(timer_cancel),\FN(get_func_ip),\FN(get_attach_cookie),\+FN(xdp_get_buff_len),\/* *//* integer value in 'imm' field of BPF_CALL instruction selects which helper
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:37
Rely on data_size_in in bpf_test_init routine signature. This is a
preliminary patch to introduce xdp multi-buff selftest
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
net/bpf/test_run.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
@@ -571,7 +570,8 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,if(kattr->test.flags||kattr->test.cpu)return-EINVAL;-data=bpf_test_init(kattr,size,NET_SKB_PAD+NET_IP_ALIGN,+data=bpf_test_init(kattr,kattr->test.data_size_in,+size,NET_SKB_PAD+NET_IP_ALIGN,SKB_DATA_ALIGN(sizeof(structskb_shared_info)));if(IS_ERR(data))returnPTR_ERR(data);
@@ -782,7 +782,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,/* XDP have extra tailroom as (most) drivers use full page */max_data_sz=4096-headroom-tailroom;-data=bpf_test_init(kattr,max_data_sz,headroom,tailroom);+data=bpf_test_init(kattr,kattr->test.data_size_in,+max_data_sz,headroom,tailroom);if(IS_ERR(data)){ret=PTR_ERR(data);gotofree_ctx;
@@ -866,7 +867,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,if(size<ETH_HLEN)return-EINVAL;-data=bpf_test_init(kattr,size,0,0);+data=bpf_test_init(kattr,kattr->test.data_size_in,size,0,0);if(IS_ERR(data))returnPTR_ERR(data);
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:39
Introduce the capability to allocate a xdp multi-buff in
bpf_prog_test_run_xdp routine. This is a preliminary patch to introduce
the selftests for new xdp multi-buff ebpf helpers
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
net/bpf/test_run.c | 54 ++++++++++++++++++++++++++++++++++++----------
1 file changed, 43 insertions(+), 11 deletions(-)
@@ -750,16 +750,16 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,unionbpf_attr__user*uattr){u32tailroom=SKB_DATA_ALIGN(sizeof(structskb_shared_info));-u32headroom=XDP_PACKET_HEADROOM;u32size=kattr->test.data_size_in;+u32headroom=XDP_PACKET_HEADROOM;+u32retval,duration,max_data_sz;u32repeat=kattr->test.repeat;structnetdev_rx_queue*rxqueue;+structskb_shared_info*sinfo;structxdp_buffxdp={};-u32retval,duration;+inti,ret=-EINVAL;structxdp_md*ctx;-u32max_data_sz;void*data;-intret=-EINVAL;if(prog->expected_attach_type==BPF_XDP_DEVMAP||prog->expected_attach_type==BPF_XDP_CPUMAP)
@@ -779,11 +779,10 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,headroom-=ctx->data;}-/* XDP have extra tailroom as (most) drivers use full page */max_data_sz=4096-headroom-tailroom;+size=min_t(u32,size,max_data_sz);-data=bpf_test_init(kattr,kattr->test.data_size_in,-max_data_sz,headroom,tailroom);+data=bpf_test_init(kattr,size,max_data_sz,headroom,tailroom);if(IS_ERR(data)){ret=PTR_ERR(data);gotofree_ctx;
@@ -793,11 +792,45 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,xdp_init_buff(&xdp,headroom+max_data_sz+tailroom,&rxqueue->xdp_rxq);xdp_prepare_buff(&xdp,data,headroom,size,true);+sinfo=xdp_get_shared_info_from_buff(&xdp);ret=xdp_convert_md_to_buff(ctx,&xdp);if(ret)gotofree_data;+if(unlikely(kattr->test.data_size_in>size)){+void__user*data_in=u64_to_user_ptr(kattr->test.data_in);++while(size<kattr->test.data_size_in){+structpage*page;+skb_frag_t*frag;+intdata_len;++page=alloc_page(GFP_KERNEL);+if(!page){+ret=-ENOMEM;+gotoout;+}++frag=&sinfo->frags[sinfo->nr_frags++];+__skb_frag_set_page(frag,page);++data_len=min_t(int,kattr->test.data_size_in-size,+PAGE_SIZE);+skb_frag_size_set(frag,data_len);++if(copy_from_user(page_address(page),data_in+size,+data_len)){+ret=-EFAULT;+gotoout;+}+sinfo->xdp_frags_tsize+=PAGE_SIZE;+sinfo->xdp_frags_size+=data_len;+size+=data_len;+}+xdp_buff_set_mb(&xdp);+}+bpf_prog_change_xdp(NULL,prog);ret=bpf_test_run(prog,&xdp,repeat,&retval,&duration,true);/* We convert the xdp_buff back to an xdp_md before checking the return
@@ -808,10 +841,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,if(ret)gotoout;-if(xdp.data_meta!=data+headroom||-xdp.data_end!=xdp.data_meta+size)-size=xdp.data_end-xdp.data_meta;-+size=xdp.data_end-xdp.data_meta+sinfo->xdp_frags_size;ret=bpf_test_finish(kattr,uattr,xdp.data_meta,size,retval,duration);if(!ret)
@@ -821,6 +851,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,out:bpf_prog_change_xdp(prog,NULL);free_data:+for(i=0;i<sinfo->nr_frags;i++)+__free_page(skb_frag_page(&sinfo->frags[i]));kfree(data);free_ctx:kfree(ctx);
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:50
introduce xdp_shared_info pointer in bpf_test_finish signature in order
to copy back paged data from a xdp multi-buff frame to userspace buffer
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
net/bpf/test_run.c | 48 +++++++++++++++++++++++++++++++++++++---------
1 file changed, 39 insertions(+), 9 deletions(-)
@@ -674,7 +703,8 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,/* bpf program can never convert linear skb to non-linear */if(WARN_ON_ONCE(skb_is_nonlinear(skb)))size=skb_headlen(skb);-ret=bpf_test_finish(kattr,uattr,skb->data,size,retval,duration);+ret=bpf_test_finish(kattr,uattr,skb->data,NULL,size,retval,+duration);if(!ret)ret=bpf_ctx_finish(kattr,uattr,ctx,sizeof(struct__sk_buff));
@@ -842,8 +872,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,gotoout;size=xdp.data_end-xdp.data_meta+sinfo->xdp_frags_size;-ret=bpf_test_finish(kattr,uattr,xdp.data_meta,size,retval,-duration);+ret=bpf_test_finish(kattr,uattr,xdp.data_meta,sinfo,size,+retval,duration);if(!ret)ret=bpf_ctx_finish(kattr,uattr,ctx,sizeof(structxdp_md));
@@ -934,8 +964,8 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,if(ret<0)gotoout;-ret=bpf_test_finish(kattr,uattr,&flow_keys,sizeof(flow_keys),-retval,duration);+ret=bpf_test_finish(kattr,uattr,&flow_keys,NULL,+sizeof(flow_keys),retval,duration);if(!ret)ret=bpf_ctx_finish(kattr,uattr,user_ctx,sizeof(structbpf_flow_keys));
@@ -1039,7 +1069,7 @@ int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *katuser_ctx->cookie=sock_gen_cookie(ctx.selected_sk);}-ret=bpf_test_finish(kattr,uattr,NULL,0,retval,duration);+ret=bpf_test_finish(kattr,uattr,NULL,NULL,0,retval,duration);if(!ret)ret=bpf_ctx_finish(kattr,uattr,user_ctx,sizeof(*user_ctx));
@@ -130,6 +130,120 @@ void test_xdp_adjust_tail_grow2(void)bpf_object__close(obj);}+voidtest_xdp_adjust_mb_tail_shrink(void)+{+constchar*file="./test_xdp_adjust_tail_shrink.o";+__u32duration,retval,size,exp_size;+structbpf_object*obj;+interr,prog_fd;+__u8*buf;++/* For the individual test cases, the first byte in the packet+*indicateswhichtestwillberun.+*/++err=bpf_prog_load(file,BPF_PROG_TYPE_XDP,&obj,&prog_fd);+if(CHECK_FAIL(err))+return;++buf=malloc(9000);+if(CHECK(!buf,"malloc()","error:%s\n",strerror(errno)))+return;++memset(buf,0,9000);++/* Test case removing 10 bytes from last frag, NOT freeing it */+exp_size=8990;/* 9000 - 10 */+err=bpf_prog_test_run(prog_fd,1,buf,9000,+buf,&size,&retval,&duration);++CHECK(err||retval!=XDP_TX||size!=exp_size,+"9k-10b","err %d errno %d retval %d[%d] size %d[%u]\n",+err,errno,retval,XDP_TX,size,exp_size);++/* Test case removing one of two pages, assuming 4K pages */+buf[0]=1;+exp_size=4900;/* 9000 - 4100 */+err=bpf_prog_test_run(prog_fd,1,buf,9000,+buf,&size,&retval,&duration);++CHECK(err||retval!=XDP_TX||size!=exp_size,+"9k-1p","err %d errno %d retval %d[%d] size %d[%u]\n",+err,errno,retval,XDP_TX,size,exp_size);++/* Test case removing two pages resulting in a non mb xdp_buff */+buf[0]=2;+exp_size=800;/* 9000 - 8200 */+err=bpf_prog_test_run(prog_fd,1,buf,9000,+buf,&size,&retval,&duration);++CHECK(err||retval!=XDP_TX||size!=exp_size,+"9k-2p","err %d errno %d retval %d[%d] size %d[%u]\n",+err,errno,retval,XDP_TX,size,exp_size);++free(buf);++bpf_object__close(obj);+}++voidtest_xdp_adjust_mb_tail_grow(void)+{+constchar*file="./test_xdp_adjust_tail_grow.o";+__u32duration,retval,size,exp_size;+structbpf_object*obj;+interr,i,prog_fd;+__u8*buf;++err=bpf_prog_load(file,BPF_PROG_TYPE_XDP,&obj,&prog_fd);+if(CHECK_FAIL(err))+return;++buf=malloc(16384);+if(CHECK(!buf,"malloc()","error:%s\n",strerror(errno)))+return;++/* Test case add 10 bytes to last frag */+memset(buf,1,16384);+size=9000;+exp_size=size+10;+err=bpf_prog_test_run(prog_fd,1,buf,size,+buf,&size,&retval,&duration);++CHECK(err||retval!=XDP_TX||size!=exp_size,+"9k+10b","err %d retval %d[%d] size %d[%u]\n",+err,retval,XDP_TX,size,exp_size);++for(i=0;i<9000;i++)+CHECK(buf[i]!=1,"9k+10b-old",+"Old data not all ok, offset %i is failing [%u]!\n",+i,buf[i]);++for(i=9000;i<9010;i++)+CHECK(buf[i]!=0,"9k+10b-new",+"New data not all ok, offset %i is failing [%u]!\n",+i,buf[i]);++for(i=9010;i<16384;i++)+CHECK(buf[i]!=1,"9k+10b-untouched",+"Unused data not all ok, offset %i is failing [%u]!\n",+i,buf[i]);++/* Test a too large grow */+memset(buf,1,16384);+size=9001;+exp_size=size;+err=bpf_prog_test_run(prog_fd,1,buf,size,+buf,&size,&retval,&duration);++CHECK(err||retval!=XDP_DROP||size!=exp_size,+"9k+10b","err %d retval %d[%d] size %d[%u]\n",+err,retval,XDP_TX,size,exp_size);++free(buf);++bpf_object__close(obj);+}+voidtest_xdp_adjust_tail(void){if(test__start_subtest("xdp_adjust_tail_shrink"))
@@ -7,11 +7,10 @@ int _xdp_adjust_tail_grow(struct xdp_md *xdp){void*data_end=(void*)(long)xdp->data_end;void*data=(void*)(long)xdp->data;-unsignedintdata_len;+intdata_len=bpf_xdp_get_buff_len(xdp);intoffset=0;/* Data length determine test case */-data_len=data_end-data;if(data_len==54){/* sizeof(pkt_v4) */offset=4096;/* test too large offset */
@@ -20,7 +19,12 @@ int _xdp_adjust_tail_grow(struct xdp_md *xdp)}elseif(data_len==64){offset=128;}elseif(data_len==128){-offset=4096-256-320-data_len;/* Max tail grow 3520 */+/* Max tail grow 3520 */+offset=4096-256-320-data_len;+}elseif(data_len==9000){+offset=10;+}elseif(data_len==9001){+offset=4096;}else{returnXDP_ABORTED;/* No matching test */}
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:43:52
For XDP frames split over multiple buffers, the xdp_md->data and
xdp_md->data_end pointers will point to the start and end of the first
fragment only. bpf_xdp_adjust_data can be used to access subsequent
fragments by moving the data pointers. To use, an XDP program can call
this helper with the byte offset of the packet payload that
it wants to access; the helper will move xdp_md->data and xdp_md ->data_end
so they point to the requested payload offset and to the end of the
fragment containing this byte offset, and return the byte offset of the
start of the fragment.
To move back to the beginning of the packet, simply call the
helper with an offset of '0'.
Note also that the helpers that modify the packet boundaries
(bpf_xdp_adjust_head(), bpf_xdp_adjust_tail() and
bpf_xdp_adjust_meta()) will fail if the pointers have been
moved; it is the responsibility of the BPF program to move them
back before using these helpers.
Suggested-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/net/xdp.h | 8 +++++
include/uapi/linux/bpf.h | 32 ++++++++++++++++++
net/bpf/test_run.c | 8 +++++
net/core/filter.c | 62 +++++++++++++++++++++++++++++++++-
tools/include/uapi/linux/bpf.h | 32 ++++++++++++++++++
5 files changed, 141 insertions(+), 1 deletion(-)
@@ -82,6 +82,11 @@ struct xdp_buff {structxdp_txq_info*txq;u32frame_sz;/* frame size to deduce data_hard_end/reserved tailroom*/u16flags;/* supported values defined in xdp_flags */+/* xdp multi-buff metadata used for frags iteration */+struct{+u16headroom;/* frame headroom: data - data_hard_start */+u16headlen;/* first buffer length: data_end - data */+}mb;};static__always_inlineboolxdp_buff_is_mb(structxdp_buff*xdp)
@@ -127,6 +132,9 @@ xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,xdp->data=data;xdp->data_end=data+data_len;xdp->data_meta=meta_valid?data:data+1;+/* mb metadata for frags iteration */+xdp->mb.headroom=headroom;+xdp->mb.headlen=data_len;}/* Reserve memory area at end-of data area.
@@ -4877,6 +4877,37 @@ union bpf_attr {*Getthetotalsizeofagivenxdpbuff(linearandpagedarea)*Return*Thetotalsizeofagivenxdpbuffer.+*+*longbpf_xdp_adjust_data(structxdp_buff*xdp_md,u32offset)+*Description+*ForXDPframessplitovermultiplebuffers,the+**xdp_md*\**->data**and*xdp_md*\**->data_end**pointers+*willpointtothestartandendofthefirstfragmentonly.+*Thishelpercanbeusedtoaccesssubsequentfragmentsby+*movingthedatapointers.Touse,anXDPprogramcancall+*thishelperwiththebyteoffsetofthepacketpayloadthat+*itwantstoaccess;thehelperwillmove*xdp_md*\**->data**+*and*xdp_md*\**->data_end**sotheypointtotherequested+*payloadoffsetandtotheendofthefragmentcontainingthis+*byteoffset,andreturnthebyteoffsetofthestartofthe+*fragment.+*Tomovebacktothebeginningofthepacket,simplycallthe+*helperwithanoffsetof'0'.+*Notealsothatthehelpersthatmodifythepacketboundaries+*(*bpf_xdp_adjust_head()*,*bpf_xdp_adjust_tail()*and+**bpf_xdp_adjust_meta()*)willfailifthepointershavebeen+*moved;itistheresponsibilityoftheBPFprogramtomovethem+*backbeforeusingthesehelpers.+*+*Acalltothishelperissusceptibletochangetheunderlying+*packetbuffer.Therefore,atloadtime,allchecksonpointers+*previouslydonebytheverifierareinvalidatedandmustbe+*performedagain,ifthehelperisusedincombinationwith+*directpacketaccess.+*Return+*offsetbetweenthebeginningofthecurrentfragmentand+*original*xdp_md*\**->data**onsuccess,oranegativeerror+*incaseoffailure.*/#define __BPF_FUNC_MAPPER(FN) \FN(unspec),\
@@ -5055,6 +5086,7 @@ union bpf_attr {FN(get_func_ip),\FN(get_attach_cookie),\FN(xdp_get_buff_len),\+FN(xdp_adjust_data),\/* *//* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -871,6 +873,12 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,if(ret)gotoout;+/* data pointers need to be reset after frag iteration */+if(unlikely(xdp.data_hard_start+xdp.mb.headroom!=xdp.data)){+ret=-EFAULT;+gotoout;+}+size=xdp.data_end-xdp.data_meta+sinfo->xdp_frags_size;ret=bpf_test_finish(kattr,uattr,xdp.data_meta,sinfo,size,retval,duration);
@@ -3827,6 +3827,10 @@ BPF_CALL_2(bpf_xdp_adjust_head, struct xdp_buff *, xdp, int, offset)void*data_start=xdp_frame_end+metalen;void*data=xdp->data+offset;+/* data pointers need to be reset after frag iteration */+if(unlikely(xdp->data_hard_start+xdp->mb.headroom!=xdp->data))+return-EINVAL;+if(unlikely(data<data_start||data>xdp->data_end-ETH_HLEN))return-EINVAL;
@@ -3910,6 +3917,10 @@ BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)void*data_hard_end=xdp_data_hard_end(xdp);/* use xdp->frame_sz */void*data_end=xdp->data_end+offset;+/* data pointer needs to be reset after frag iteration */+if(unlikely(xdp->data+xdp->mb.headlen!=xdp->data_end))+return-EINVAL;+if(unlikely(xdp_buff_is_mb(xdp)))returnbpf_xdp_mb_adjust_tail(xdp,offset);
@@ -3949,6 +3960,10 @@ BPF_CALL_2(bpf_xdp_adjust_meta, struct xdp_buff *, xdp, int, offset)void*meta=xdp->data_meta+offset;unsignedlongmetalen=xdp->data-meta;+/* data pointer needs to be reset after frag iteration */+if(unlikely(xdp->data_hard_start+xdp->mb.headroom!=xdp->data))+return-EINVAL;+if(xdp_data_meta_unsupported(xdp))return-ENOTSUPP;if(unlikely(meta<xdp_frame_end||
@@ -3970,6 +3985,48 @@ static const struct bpf_func_proto bpf_xdp_adjust_meta_proto = {.arg2_type=ARG_ANYTHING,};+BPF_CALL_2(bpf_xdp_adjust_data,structxdp_buff*,xdp,u32,offset)+{+structskb_shared_info*sinfo=xdp_get_shared_info_from_buff(xdp);+u32base_offset=xdp->mb.headlen;+inti;++if(!xdp_buff_is_mb(xdp)||offset>sinfo->xdp_frags_size)+return-EINVAL;++if(offset<xdp->mb.headlen){+/* linear area */+xdp->data=xdp->data_hard_start+xdp->mb.headroom+offset;+xdp->data_end=xdp->data_hard_start+xdp->mb.headroom++xdp->mb.headlen;+return0;+}++for(i=0;i<sinfo->nr_frags;i++){+/* paged area */+skb_frag_t*frag=&sinfo->frags[i];+unsignedintsize=skb_frag_size(frag);++if(offset<base_offset+size){+u8*addr=skb_frag_address(frag);++xdp->data=addr+offset-base_offset;+xdp->data_end=addr+size;+break;+}+base_offset+=size;+}+returnbase_offset;+}++staticconststructbpf_func_protobpf_xdp_adjust_data_proto={+.func=bpf_xdp_adjust_data,+.gpl_only=false,+.ret_type=RET_INTEGER,+.arg1_type=ARG_PTR_TO_CTX,+.arg2_type=ARG_ANYTHING,+};+/* XDP_REDIRECT works by a three-step process, implemented in the functions*below:*
@@ -4877,6 +4877,37 @@ union bpf_attr {*Getthetotalsizeofagivenxdpbuff(linearandpagedarea)*Return*Thetotalsizeofagivenxdpbuffer.+*+*longbpf_xdp_adjust_data(structxdp_buff*xdp_md,u32offset)+*Description+*ForXDPframessplitovermultiplebuffers,the+**xdp_md*\**->data**and*xdp_md*\**->data_end**pointers+*willpointtothestartandendofthefirstfragmentonly.+*Thishelpercanbeusedtoaccesssubsequentfragmentsby+*movingthedatapointers.Touse,anXDPprogramcancall+*thishelperwiththebyteoffsetofthepacketpayloadthat+*itwantstoaccess;thehelperwillmove*xdp_md*\**->data**+*and*xdp_md*\**->data_end**sotheypointtotherequested+*payloadoffsetandtotheendofthefragmentcontainingthis+*byteoffset,andreturnthebyteoffsetofthestartofthe+*fragment.+*Tomovebacktothebeginningofthepacket,simplycallthe+*helperwithanoffsetof'0'.+*Notealsothatthehelpersthatmodifythepacketboundaries+*(*bpf_xdp_adjust_head()*,*bpf_xdp_adjust_tail()*and+**bpf_xdp_adjust_meta()*)willfailifthepointershavebeen+*moved;itistheresponsibilityoftheBPFprogramtomovethem+*backbeforeusingthesehelpers.+*+*Acalltothishelperissusceptibletochangetheunderlying+*packetbuffer.Therefore,atloadtime,allchecksonpointers+*previouslydonebytheverifierareinvalidatedandmustbe+*performedagain,ifthehelperisusedincombinationwith+*directpacketaccess.+*Return+*offsetbetweenthebeginningofthecurrentfragmentand+*original*xdp_md*\**->data**onsuccess,oranegativeerror+*incaseoffailure.*/#define __BPF_FUNC_MAPPER(FN) \FN(unspec),\
@@ -5055,6 +5086,7 @@ union bpf_attr {FN(get_func_ip),\FN(get_attach_cookie),\FN(xdp_get_buff_len),\+FN(xdp_adjust_data),\/* *//* integer value in 'imm' field of BPF_CALL instruction selects which helper
From: Lorenzo Bianconi <lorenzo@kernel.org> Date: 2021-08-20 15:45:42
From: Eelco Chaudron <echaudro@redhat.com>
This change adds support for tail growing and shrinking for XDP multi-buff.
When called on a multi-buffer packet with a grow request, it will always
work on the last fragment of the packet. So the maximum grow size is the
last fragments tailroom, i.e. no new buffer will be allocated.
When shrinking, it will work from the last fragment, all the way down to
the base buffer depending on the shrinking size. It's important to mention
that once you shrink down the fragment(s) are freed, so you can not grow
again to the original size.
Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
---
include/net/xdp.h | 9 +++++++
net/core/filter.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
net/core/xdp.c | 5 ++--
3 files changed, 72 insertions(+), 2 deletions(-)
@@ -4619,10 +4628,52 @@ static const struct bpf_func_proto bpf_sk_ancestor_cgroup_id_proto = {};#endif-staticunsignedlongbpf_xdp_copy(void*dst_buff,constvoid*src_buff,+staticunsignedlongbpf_xdp_copy(void*dst_buff,constvoid*ctx,unsignedlongoff,unsignedlonglen){-memcpy(dst_buff,src_buff+off,len);+unsignedlongbase_len,copy_len,frag_off_total;+structxdp_buff*xdp=(structxdp_buff*)ctx;+structskb_shared_info*sinfo;+inti;++if(likely(!xdp_buff_is_mb(xdp))){+memcpy(dst_buff,xdp->data+off,len);+return0;+}++base_len=xdp->data_end-xdp->data;+frag_off_total=base_len;+sinfo=xdp_get_shared_info_from_buff(xdp);++/* If we need to copy data from the base buffer do it */+if(off<base_len){+copy_len=min(len,base_len-off);+memcpy(dst_buff,xdp->data+off,copy_len);++off+=copy_len;+len-=copy_len;+dst_buff+=copy_len;+}++/* Copy any remaining data from the fragments */+for(i=0;len&&i<sinfo->nr_frags;i++){+skb_frag_t*frag=&sinfo->frags[i];+unsignedlongfrag_len,frag_off;++frag_len=skb_frag_size(frag);+frag_off=off-frag_off_total;+if(frag_off<frag_len){+copy_len=min(len,frag_len-frag_off);+memcpy(dst_buff,+skb_frag_address(frag)+frag_off,copy_len);++off+=copy_len;+len-=copy_len;+dst_buff+=copy_len;+}+frag_off_total+=frag_len;+}+return0;}
@@ -10,11 +10,20 @@ struct meta {intpkt_len;};+structtest_ctx_s{+boolpassed;+intpkt_size;+};++structtest_ctx_stest_ctx;+staticvoidon_sample(void*ctx,intcpu,void*data,__u32size){-intduration=0;structmeta*meta=(structmeta*)data;structipv4_packet*trace_pkt_v4=data+sizeof(*meta);+unsignedchar*raw_pkt=data+sizeof(*meta);+structtest_ctx_s*tst_ctx=ctx;+intduration=0;if(CHECK(size<sizeof(pkt_v4)+sizeof(*meta),"check_size","size %u < %zu\n",
@@ -25,25 +34,114 @@ static void on_sample(void *ctx, int cpu, void *data, __u32 size)"meta->ifindex = %d\n",meta->ifindex))return;-if(CHECK(meta->pkt_len!=sizeof(pkt_v4),"check_meta_pkt_len",-"meta->pkt_len = %zd\n",sizeof(pkt_v4)))+if(CHECK(meta->pkt_len!=tst_ctx->pkt_size,"check_meta_pkt_len",+"meta->pkt_len = %d\n",tst_ctx->pkt_size))return;if(CHECK(memcmp(trace_pkt_v4,&pkt_v4,sizeof(pkt_v4)),"check_packet_content","content not the same\n"))return;-*(bool*)ctx=true;+if(meta->pkt_len>sizeof(pkt_v4)){+for(inti=0;i<(meta->pkt_len-sizeof(pkt_v4));i++){+if(raw_pkt[i+sizeof(pkt_v4)]!=(unsignedchar)i){+CHECK(true,"check_packet_content",+"byte %zu does not match %u != %u\n",+i+sizeof(pkt_v4),+raw_pkt[i+sizeof(pkt_v4)],+(unsignedchar)i);+break;+}+}+}++tst_ctx->passed=true;}-voidtest_xdp_bpf2bpf(void)+#define BUF_SZ 9000++staticintrun_xdp_bpf2bpf_pkt_size(intpkt_fd,structperf_buffer*pb,+structtest_xdp_bpf2bpf*ftrace_skel,+intpkt_size){__u32duration=0,retval,size;-charbuf[128];+__u8*buf,*buf_in;+interr,ret=0;++if(pkt_size>BUF_SZ||pkt_size<sizeof(pkt_v4))+return-EINVAL;++buf_in=malloc(BUF_SZ);+if(CHECK(!buf_in,"buf_in malloc()","error:%s\n",strerror(errno)))+return-ENOMEM;++buf=malloc(BUF_SZ);+if(CHECK(!buf,"buf malloc()","error:%s\n",strerror(errno))){+ret=-ENOMEM;+gotofree_buf_in;+}++test_ctx.passed=false;+test_ctx.pkt_size=pkt_size;++memcpy(buf_in,&pkt_v4,sizeof(pkt_v4));+if(pkt_size>sizeof(pkt_v4)){+for(inti=0;i<(pkt_size-sizeof(pkt_v4));i++)+buf_in[i+sizeof(pkt_v4)]=i;+}++/* Run test program */+err=bpf_prog_test_run(pkt_fd,1,buf_in,pkt_size,+buf,&size,&retval,&duration);++if(CHECK(err||retval!=XDP_PASS||size!=pkt_size,+"ipv4","err %d errno %d retval %d size %d\n",+err,errno,retval,size)){+ret=err?err:-EINVAL;+gotofree_buf;+}++/* Make sure bpf_xdp_output() was triggered and it sent the expected+*datatotheperfringbuffer.+*/+err=perf_buffer__poll(pb,100);+if(CHECK(err<=0,"perf_buffer__poll","err %d\n",err)){+ret=-EINVAL;+gotofree_buf;+}++if(CHECK_FAIL(!test_ctx.passed)){+ret=-EINVAL;+gotofree_buf;+}++/* Verify test results */+if(CHECK(ftrace_skel->bss->test_result_fentry!=if_nametoindex("lo"),+"result","fentry failed err %llu\n",+ftrace_skel->bss->test_result_fentry)){+ret=-EINVAL;+gotofree_buf;+}++if(CHECK(ftrace_skel->bss->test_result_fexit!=XDP_PASS,"result",+"fexit failed err %llu\n",+ftrace_skel->bss->test_result_fexit))+ret=-EINVAL;++free_buf:+free(buf);+free_buf_in:+free(buf_in);++returnret;+}++voidtest_xdp_bpf2bpf(void)+{interr,pkt_fd,map_fd;-boolpassed=false;-structiphdr*iph=(void*)buf+sizeof(structethhdr);-structiptnl_infovalue4={.family=AF_INET};+__u32duration=0;+intpkt_sizes[]={sizeof(pkt_v4),1024,4100,8200};+structiptnl_infovalue4={.family=AF_INET6};structtest_xdp*pkt_skel=NULL;structtest_xdp_bpf2bpf*ftrace_skel=NULL;structvipkey4={.protocol=6,.family=AF_INET};
@@ -87,40 +185,15 @@ void test_xdp_bpf2bpf(void)/* Set up perf buffer */pb_opts.sample_cb=on_sample;-pb_opts.ctx=&passed;+pb_opts.ctx=&test_ctx;pb=perf_buffer__new(bpf_map__fd(ftrace_skel->maps.perf_buf_map),-1,&pb_opts);+8,&pb_opts);if(!ASSERT_OK_PTR(pb,"perf_buf__new"))gotoout;-/* Run test program */-err=bpf_prog_test_run(pkt_fd,1,&pkt_v4,sizeof(pkt_v4),-buf,&size,&retval,&duration);--if(CHECK(err||retval!=XDP_TX||size!=74||-iph->protocol!=IPPROTO_IPIP,"ipv4",-"err %d errno %d retval %d size %d\n",-err,errno,retval,size))-gotoout;--/* Make sure bpf_xdp_output() was triggered and it sent the expected-*datatotheperfringbuffer.-*/-err=perf_buffer__poll(pb,100);-if(CHECK(err<0,"perf_buffer__poll","err %d\n",err))-gotoout;--CHECK_FAIL(!passed);--/* Verify test results */-if(CHECK(ftrace_skel->bss->test_result_fentry!=if_nametoindex("lo"),-"result","fentry failed err %llu\n",-ftrace_skel->bss->test_result_fentry))-gotoout;--CHECK(ftrace_skel->bss->test_result_fexit!=XDP_TX,"result",-"fexit failed err %llu\n",ftrace_skel->bss->test_result_fexit);-+for(inti=0;i<ARRAY_SIZE(pkt_sizes);i++)+run_xdp_bpf2bpf_pkt_size(pkt_fd,pb,ftrace_skel,+pkt_sizes[i]);out:if(pb)perf_buffer__free(pb);
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:13:34
Lorenzo Bianconi wrote:
Introduce xdp_frags_tsize field in skb_shared_info data structure
to store xdp_buff/xdp_frame truesize (xdp_frags_tsize will be used
in xdp multi-buff support). In order to not increase skb_shared_info
size we will use a hole due to skb_shared_info alignment.
Introduce xdp_frags_size field in skb_shared_info data structure
reusing gso_type field in order to store xdp_buff/xdp_frame paged size.
xdp_frags_size will be used in xdp multi-buff support.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
I assume we can use xdp_frags_tsize for anything else above XDP later?
Other than simple question looks OK to me.
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:15:51
Lorenzo Bianconi wrote:
Introduce flags field in xdp_frame and xdp_buffer data structures
to define additional buffer features. At the moment the only
supported buffer feature is multi-buffer bit (mb). Multi-buffer bit
is used to specify if this is a linear buffer (mb = 0) or a multi-buffer
frame (mb = 1). In the latter case the driver is expected to initialize
the skb_shared_info structure at the end of the first buffer to link
together subsequent buffers belonging to the same frame.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:24:07
Lorenzo Bianconi wrote:
quoted hunk
Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and
XDP remote drivers if this is a "non-linear" XDP buffer. Access
skb_shared_info only if xdp_buff mb is set in order to avoid possible
cache-misses.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
Not that I care much, but couldn't you just init num_frags = 0 and
avoid the goto?
Anyways its not my driver so no need to change it if you like it better
the way it is. Mostly just checking my understanding.
quoted hunk
for (i = 0; i < num_frags; i++) {
skb_frag_t *frag = &sinfo->frags[i];
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:34:11
Lorenzo Bianconi wrote:
Relying on xdp mb bit, remove skb_shared_info structure allocated on the
stack in mvneta_rx_swbm routine and simplify mvneta_swbm_add_rx_fragment
accessing skb_shared_info in the xdp_buff structure directly. There is no
performance penalty in this approach since mvneta_swbm_add_rx_fragment
is run just for multi-buff use-case.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:39:01
Lorenzo Bianconi wrote:
Introduce xdp_update_skb_shared_info routine to update frags array
metadata in skb_shared_info data structure converting to a skb from
a xdp_buff or xdp_frame.
According to the current skb_shared_info architecture in
xdp_frame/xdp_buff and to the xdp multi-buff support, there is
no need to run skb_add_rx_frag() and reset frags array converting the buffer
to a skb since the frag array will be in the same position for xdp_buff/xdp_frame
and for the skb, we just need to update memory metadata.
Introduce XDP_FLAGS_PF_MEMALLOC flag in xdp_buff_flags in order to mark
the xdp_buff or xdp_frame as under memory-pressure if pages of the frags array
are under memory pressure. Doing so we can avoid looping over all fragments in
xdp_update_skb_shared_info routine. The driver is expected to set the
flag constructing the xdp_buffer using xdp_buff_set_frag_pfmemalloc
utility routine.
Rely on xdp_update_skb_shared_info in __xdp_build_skb_from_frame routine
converting the multi-buff xdp_frame to a skb after performing a XDP_REDIRECT.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:42:06
Lorenzo Bianconi wrote:
Rely on xdp_update_skb_shared_info routine in order to avoid
resetting frags array in skb_shared_info structure building
the skb in mvneta_swbm_build_skb(). Frags array is expected to
be initialized by the receiving driver building the xdp_buff
and here we just need to update memory metadata.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
@@ -2304,11 +2304,19 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,skb_frag_size_set(frag,data_len);__skb_frag_set_page(frag,page);-if(!xdp_buff_is_mb(xdp))+if(!xdp_buff_is_mb(xdp)){+sinfo->xdp_frags_size=*size;xdp_buff_set_mb(xdp);+}+if(page_is_pfmemalloc(page))+xdp_buff_set_frag_pfmemalloc(xdp);}else{page_pool_put_full_page(rxq->page_pool,page,true);}++/* last fragment */+if(len==*size)+sinfo->xdp_frags_tsize=sinfo->nr_frags*PAGE_SIZE;*size-=len;}
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:43:48
Lorenzo Bianconi wrote:
Take into account if the received xdp_buff/xdp_frame is non-linear
recycling/returning the frame memory to the allocator or into
xdp_frame_bulk.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-08-31 23:44:55
Lorenzo Bianconi wrote:
Introduce the capability to map non-linear xdp buffer running
mvneta_xdp_submit_frame() for XDP_TX and XDP_REDIRECT
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-09-01 00:10:56
Lorenzo Bianconi wrote:
From: Eelco Chaudron <echaudro@redhat.com>
This change adds support for tail growing and shrinking for XDP multi-buff.
When called on a multi-buffer packet with a grow request, it will always
work on the last fragment of the packet. So the maximum grow size is the
last fragments tailroom, i.e. no new buffer will be allocated.
When shrinking, it will work from the last fragment, all the way down to
the base buffer depending on the shrinking size. It's important to mention
that once you shrink down the fragment(s) are freed, so you can not grow
again to the original size.
Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
---
LGTM.
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-09-01 00:12:33
Lorenzo Bianconi wrote:
Introduce bpf_xdp_get_buff_len helper in order to return the xdp buffer
total size (linear and paged area)
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-09-01 00:19:54
Lorenzo Bianconi wrote:
From: Eelco Chaudron <echaudro@redhat.com>
This patch adds support for multi-buffer for the following helpers:
- bpf_xdp_output()
- bpf_perf_event_output()
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-09-01 00:37:04
Lorenzo Bianconi wrote:
For XDP frames split over multiple buffers, the xdp_md->data and
xdp_md->data_end pointers will point to the start and end of the first
fragment only. bpf_xdp_adjust_data can be used to access subsequent
fragments by moving the data pointers. To use, an XDP program can call
this helper with the byte offset of the packet payload that
it wants to access; the helper will move xdp_md->data and xdp_md ->data_end
so they point to the requested payload offset and to the end of the
fragment containing this byte offset, and return the byte offset of the
start of the fragment.
To move back to the beginning of the packet, simply call the
helper with an offset of '0'.
Note also that the helpers that modify the packet boundaries
(bpf_xdp_adjust_head(), bpf_xdp_adjust_tail() and
bpf_xdp_adjust_meta()) will fail if the pointers have been
moved; it is the responsibility of the BPF program to move them
back before using these helpers.
I'm ok with this for a first iteration I guess with more work we
can make the helpers use the updated pointers though.
Suggested-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Overall looks good couple small nits/questions below. Thanks!
@@ -82,6 +82,11 @@ struct xdp_buff {structxdp_txq_info*txq;u32frame_sz;/* frame size to deduce data_hard_end/reserved tailroom*/u16flags;/* supported values defined in xdp_flags */+/* xdp multi-buff metadata used for frags iteration */+struct{+u16headroom;/* frame headroom: data - data_hard_start */+u16headlen;/* first buffer length: data_end - data */+}mb;};static__always_inlineboolxdp_buff_is_mb(structxdp_buff*xdp)
@@ -127,6 +132,9 @@ xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,xdp->data=data;xdp->data_end=data+data_len;xdp->data_meta=meta_valid?data:data+1;+/* mb metadata for frags iteration */+xdp->mb.headroom=headroom;+xdp->mb.headlen=data_len;}/* Reserve memory area at end-of data area.
@@ -4877,6 +4877,37 @@ union bpf_attr {*Getthetotalsizeofagivenxdpbuff(linearandpagedarea)*Return*Thetotalsizeofagivenxdpbuffer.+*+*longbpf_xdp_adjust_data(structxdp_buff*xdp_md,u32offset)+*Description+*ForXDPframessplitovermultiplebuffers,the+**xdp_md*\**->data**and*xdp_md*\**->data_end**pointers
^^^^
missing space?
quoted hunk
+ * will point to the start and end of the first fragment only.
+ * This helper can be used to access subsequent fragments by
+ * moving the data pointers. To use, an XDP program can call
+ * this helper with the byte offset of the packet payload that
+ * it wants to access; the helper will move *xdp_md*\ **->data**
+ * and *xdp_md *\ **->data_end** so they point to the requested
+ * payload offset and to the end of the fragment containing this
+ * byte offset, and return the byte offset of the start of the
+ * fragment.
+ * To move back to the beginning of the packet, simply call the
+ * helper with an offset of '0'.
+ * Note also that the helpers that modify the packet boundaries
+ * (*bpf_xdp_adjust_head()*, *bpf_xdp_adjust_tail()* and
+ * *bpf_xdp_adjust_meta()*) will fail if the pointers have been
+ * moved; it is the responsibility of the BPF program to move them
+ * back before using these helpers.
+ *
+ * A call to this helper is susceptible to change the underlying
+ * packet buffer. Therefore, at load time, all checks on pointers
+ * previously done by the verifier are invalidated and must be
+ * performed again, if the helper is used in combination with
+ * direct packet access.
+ * Return
+ * offset between the beginning of the current fragment and
+ * original *xdp_md*\ **->data** on success, or a negative error
+ * in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5055,6 +5086,7 @@ union bpf_attr { FN(get_func_ip), \ FN(get_attach_cookie), \ FN(xdp_get_buff_len), \+ FN(xdp_adjust_data), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -871,6 +873,12 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,if(ret)gotoout;+/* data pointers need to be reset after frag iteration */+if(unlikely(xdp.data_hard_start+xdp.mb.headroom!=xdp.data)){+ret=-EFAULT;+gotoout;+}+size=xdp.data_end-xdp.data_meta+sinfo->xdp_frags_size;ret=bpf_test_finish(kattr,uattr,xdp.data_meta,sinfo,size,retval,duration);
@@ -3827,6 +3827,10 @@ BPF_CALL_2(bpf_xdp_adjust_head, struct xdp_buff *, xdp, int, offset)void*data_start=xdp_frame_end+metalen;void*data=xdp->data+offset;+/* data pointers need to be reset after frag iteration */+if(unlikely(xdp->data_hard_start+xdp->mb.headroom!=xdp->data))+return-EINVAL;
-EFAULT? It might be nice if error code is different from below
for debugging?
quoted hunk
+
if (unlikely(data < data_start ||
data > xdp->data_end - ETH_HLEN))
return -EINVAL;
From: John Fastabend <john.fastabend@gmail.com> Date: 2021-09-01 00:45:23
Lorenzo Bianconi wrote:
This series introduce XDP multi-buffer support. The mvneta driver is
the first to support these new "non-linear" xdp_{buff,frame}. Reviewers
please focus on how these new types of xdp_{buff,frame} packets
traverse the different layers and the layout design. It is on purpose
that BPF-helpers are kept simple, as we don't want to expose the
internal layout to allow later changes.
The main idea for the new multi-buffer layout is to reuse the same
structure used for non-linear SKB. This rely on the "skb_shared_info"
struct at the end of the first buffer to link together subsequent
buffers. Keeping the layout compatible with SKBs is also done to ease
and speedup creating a SKB from an xdp_{buff,frame}.
Converting xdp_frame to SKB and deliver it to the network stack is shown
in patch 05/18 (e.g. cpumaps).
A multi-buffer bit (mb) has been introduced in the flags field of xdp_{buff,frame}
structure to notify the bpf/network layer if this is a xdp multi-buffer frame
(mb = 1) or not (mb = 0).
The mb bit will be set by a xdp multi-buffer capable driver only for
non-linear frames maintaining the capability to receive linear frames
without any extra cost since the skb_shared_info structure at the end
of the first buffer will be initialized only if mb is set.
Moreover the flags field in xdp_{buff,frame} will be reused even for
xdp rx csum offloading in future series.
The series is looking really close to me. Couple small comments/questions
inline. Also I think we should call out the potential issues in the cover
letter with regards to backwards compatibility. Something like,
"
A multi-buffer enabled NIC may receive XDP frames with multiple frags.
If a BPF program does not understand mb layouts its possible to contrive
a BPF program that incorrectly views data_end as the end of data when
there is more data in the payload. Note helpers will generally due the
correct thing, for example perf_output will consume entire payload. But,
it is still possible some programs could do the wrong thing even if in
an edge case. Although we expect most BPF programs not to be impacted
we can't rule out, you've been warned.
"
I can't think of an elegant way around this and it does require at least
some type of opt-in by increasing the MTU limit so I'm OK with it given
I think it should impact few (no?) real programs.
Typical use cases for this series are:
- Jumbo-frames
- Packet header split (please see Google���s use-case @ NetDevConf 0x14, [0])
- TSO/GRO
The two following ebpf helpers (and related selftests) has been introduced:
- bpf_xdp_adjust_data:
Move xdp_md->data and xdp_md->data_end pointers in subsequent fragments
according to the offset provided by the ebpf program. This helper can be
used to read/write values in frame payload.
- bpf_xdp_get_buff_len:
Return the total frame size (linear + paged parts)
bpf_xdp_adjust_tail and bpf_xdp_copy helpers have been modified to take into
account xdp multi-buff frames.
More info about the main idea behind this approach can be found here [1][2].
Changes since v11:
- add missing static to bpf_xdp_get_buff_len_proto structure
- fix bpf_xdp_adjust_data helper when offset is smaller than linear area length.
Changes since v10:
- move xdp->data to the requested payload offset instead of to the beginning of
the fragment in bpf_xdp_adjust_data()
Changes since v9:
- introduce bpf_xdp_adjust_data helper and related selftest
- add xdp_frags_size and xdp_frags_tsize fields in skb_shared_info
- introduce xdp_update_skb_shared_info utility routine in ordere to not reset
frags array in skb_shared_info converting from a xdp_buff/xdp_frame to a skb
- simplify bpf_xdp_copy routine
Changes since v8:
- add proper dma unmapping if XDP_TX fails on mvneta for a xdp multi-buff
- switch back to skb_shared_info implementation from previous xdp_shared_info
one
- avoid using a bietfield in xdp_buff/xdp_frame since it introduces performance
regressions. Tested now on 10G NIC (ixgbe) to verify there are no performance
penalties for regular codebase
- add bpf_xdp_get_buff_len helper and remove frame_length field in xdp ctx
- add data_len field in skb_shared_info struct
- introduce XDP_FLAGS_FRAGS_PF_MEMALLOC flag
Changes since v7:
- rebase on top of bpf-next
- fix sparse warnings
- improve comments for frame_length in include/net/xdp.h
Changes since v6:
- the main difference respect to previous versions is the new approach proposed
by Eelco to pass full length of the packet to eBPF layer in XDP context
- reintroduce multi-buff support to eBPF kself-tests
- reintroduce multi-buff support to bpf_xdp_adjust_tail helper
- introduce multi-buffer support to bpf_xdp_copy helper
- rebase on top of bpf-next
Changes since v5:
- rebase on top of bpf-next
- initialize mb bit in xdp_init_buff() and drop per-driver initialization
- drop xdp->mb initialization in xdp_convert_zc_to_xdp_frame()
- postpone introduction of frame_length field in XDP ctx to another series
- minor changes
Changes since v4:
- rebase ontop of bpf-next
- introduce xdp_shared_info to build xdp multi-buff instead of using the
skb_shared_info struct
- introduce frame_length in xdp ctx
- drop previous bpf helpers
- fix bpf_xdp_adjust_tail for xdp multi-buff
- introduce xdp multi-buff self-tests for bpf_xdp_adjust_tail
- fix xdp_return_frame_bulk for xdp multi-buff
Changes since v3:
- rebase ontop of bpf-next
- add patch 10/13 to copy back paged data from a xdp multi-buff frame to
userspace buffer for xdp multi-buff selftests
Changes since v2:
- add throughput measurements
- drop bpf_xdp_adjust_mb_header bpf helper
- introduce selftest for xdp multibuffer
- addressed comments on bpf_xdp_get_frags_count
- introduce xdp multi-buff support to cpumaps
Changes since v1:
- Fix use-after-free in xdp_return_{buff/frame}
- Introduce bpf helpers
- Introduce xdp_mb sample program
- access skb_shared_info->nr_frags only on the last fragment
Changes since RFC:
- squash multi-buffer bit initialization in a single patch
- add mvneta non-linear XDP buff support for tx side
[0] https://netdevconf.info/0x14/session.html?talk-the-path-to-tcp-4k-mtu-and-rx-zerocopy
[1] https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org
[2] https://netdevconf.info/0x14/session.html?tutorial-add-XDP-support-to-a-NIC-driver (XDPmulti-buffers section)
Eelco Chaudron (3):
bpf: add multi-buff support to the bpf_xdp_adjust_tail() API
bpf: add multi-buffer support to xdp copy helpers
bpf: update xdp_adjust_tail selftest to include multi-buffer
Lorenzo Bianconi (15):
net: skbuff: add size metadata to skb_shared_info for xdp
xdp: introduce flags field in xdp_buff/xdp_frame
net: mvneta: update mb bit before passing the xdp buffer to eBPF layer
net: mvneta: simplify mvneta_swbm_add_rx_fragment management
net: xdp: add xdp_update_skb_shared_info utility routine
net: marvell: rely on xdp_update_skb_shared_info utility routine
xdp: add multi-buff support to xdp_return_{buff/frame}
net: mvneta: add multi buffer support to XDP_TX
net: mvneta: enable jumbo frames for XDP
bpf: introduce bpf_xdp_get_buff_len helper
bpf: move user_size out of bpf_test_init
bpf: introduce multibuff support to bpf_prog_test_run_xdp()
bpf: test_run: add xdp_shared_info pointer in bpf_test_finish
signature
net: xdp: introduce bpf_xdp_adjust_data helper
bpf: add bpf_xdp_adjust_data selftest
drivers/net/ethernet/marvell/mvneta.c | 204 ++++++++++-------
include/linux/skbuff.h | 6 +-
include/net/xdp.h | 95 +++++++-
include/uapi/linux/bpf.h | 39 ++++
kernel/trace/bpf_trace.c | 3 +
net/bpf/test_run.c | 117 ++++++++--
net/core/filter.c | 213 +++++++++++++++++-
net/core/xdp.c | 76 ++++++-
tools/include/uapi/linux/bpf.h | 39 ++++
.../bpf/prog_tests/xdp_adjust_data.c | 55 +++++
.../bpf/prog_tests/xdp_adjust_tail.c | 118 ++++++++++
.../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 151 +++++++++----
.../bpf/progs/test_xdp_adjust_tail_grow.c | 10 +-
.../bpf/progs/test_xdp_adjust_tail_shrink.c | 32 ++-
.../selftests/bpf/progs/test_xdp_bpf2bpf.c | 2 +-
.../bpf/progs/test_xdp_update_frags.c | 41 ++++
16 files changed, 1036 insertions(+), 165 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_adjust_data.c
create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_update_frags.c
--
2.31.1
From: Lorenzo Bianconi <hidden> Date: 2021-09-03 17:13:33
Lorenzo Bianconi wrote:
quoted
Introduce xdp_frags_tsize field in skb_shared_info data structure
to store xdp_buff/xdp_frame truesize (xdp_frags_tsize will be used
in xdp multi-buff support). In order to not increase skb_shared_info
size we will use a hole due to skb_shared_info alignment.
Introduce xdp_frags_size field in skb_shared_info data structure
reusing gso_type field in order to store xdp_buff/xdp_frame paged size.
xdp_frags_size will be used in xdp multi-buff support.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
I assume we can use xdp_frags_tsize for anything else above XDP later?
Other than simple question looks OK to me.
yes, right as we did for gso_type/xdp_frags_size.
Regards,
Lorenzo
Acked-by: John Fastabend <john.fastabend@gmail.com>
From: Lorenzo Bianconi <hidden> Date: 2021-09-03 17:23:16
On Wed, Sep 1, 2021 at 1:24 AM John Fastabend [off-list ref] wrote:
Lorenzo Bianconi wrote:
quoted
Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and
XDP remote drivers if this is a "non-linear" XDP buffer. Access
skb_shared_info only if xdp_buff mb is set in order to avoid possible
cache-misses.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
drivers/net/ethernet/marvell/mvneta.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
Wouldn't nr_frags = 0 in the !xdp_buff_is_mb case? Is the
xdp_buff_is_mb check with goto really required?
if xdp_buff_is_mb is false, nr_frags will not be initialized otherwise
we will trigger a cache-miss for the single-buffer use case (where
initializing skb_shared_info is not required).
quoted
for (i = 0; i < sinfo->nr_frags; i++)
page_pool_put_full_page(rxq->page_pool,
skb_frag_page(&sinfo->frags[i]), true);
+
+out:
page_pool_put_page(rxq->page_pool, virt_to_head_page(xdp->data),
sync_len, true);
}
From: Lorenzo Bianconi <hidden> Date: 2021-09-03 17:27:14
Lorenzo Bianconi wrote:
quoted
Rely on xdp_update_skb_shared_info routine in order to avoid
resetting frags array in skb_shared_info structure building
the skb in mvneta_swbm_build_skb(). Frags array is expected to
be initialized by the receiving driver building the xdp_buff
and here we just need to update memory metadata.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Acked-by: John Fastabend <john.fastabend@gmail.com>
@@ -2304,11 +2304,19 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,skb_frag_size_set(frag,data_len);__skb_frag_set_page(frag,page);-if(!xdp_buff_is_mb(xdp))+if(!xdp_buff_is_mb(xdp)){+sinfo->xdp_frags_size=*size;xdp_buff_set_mb(xdp);+}+if(page_is_pfmemalloc(page))+xdp_buff_set_frag_pfmemalloc(xdp);}else{page_pool_put_full_page(rxq->page_pool,page,true);}++/* last fragment */+if(len==*size)+sinfo->xdp_frags_tsize=sinfo->nr_frags*PAGE_SIZE;*size-=len;}
From: Lorenzo Bianconi <hidden> Date: 2021-09-03 17:57:50
Lorenzo Bianconi wrote:
quoted
For XDP frames split over multiple buffers, the xdp_md->data and
xdp_md->data_end pointers will point to the start and end of the first
fragment only. bpf_xdp_adjust_data can be used to access subsequent
fragments by moving the data pointers. To use, an XDP program can call
this helper with the byte offset of the packet payload that
it wants to access; the helper will move xdp_md->data and xdp_md ->data_end
so they point to the requested payload offset and to the end of the
fragment containing this byte offset, and return the byte offset of the
start of the fragment.
To move back to the beginning of the packet, simply call the
helper with an offset of '0'.
Note also that the helpers that modify the packet boundaries
(bpf_xdp_adjust_head(), bpf_xdp_adjust_tail() and
bpf_xdp_adjust_meta()) will fail if the pointers have been
moved; it is the responsibility of the BPF program to move them
back before using these helpers.
I'm ok with this for a first iteration I guess with more work we
can make the helpers use the updated pointers though.
quoted
Suggested-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Overall looks good couple small nits/questions below. Thanks!
@@ -82,6 +82,11 @@ struct xdp_buff {structxdp_txq_info*txq;u32frame_sz;/* frame size to deduce data_hard_end/reserved tailroom*/u16flags;/* supported values defined in xdp_flags */+/* xdp multi-buff metadata used for frags iteration */+struct{+u16headroom;/* frame headroom: data - data_hard_start */+u16headlen;/* first buffer length: data_end - data */+}mb;};static__always_inlineboolxdp_buff_is_mb(structxdp_buff*xdp)
@@ -127,6 +132,9 @@ xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,xdp->data=data;xdp->data_end=data+data_len;xdp->data_meta=meta_valid?data:data+1;+/* mb metadata for frags iteration */+xdp->mb.headroom=headroom;+xdp->mb.headlen=data_len;}/* Reserve memory area at end-of data area.
@@ -4877,6 +4877,37 @@ union bpf_attr {*Getthetotalsizeofagivenxdpbuff(linearandpagedarea)*Return*Thetotalsizeofagivenxdpbuffer.+*+*longbpf_xdp_adjust_data(structxdp_buff*xdp_md,u32offset)+*Description+*ForXDPframessplitovermultiplebuffers,the+**xdp_md*\**->data**and*xdp_md*\**->data_end**pointers
^^^^
missing space?
ack, right. I will fix it.
quoted
+ * will point to the start and end of the first fragment only.
+ * This helper can be used to access subsequent fragments by
+ * moving the data pointers. To use, an XDP program can call
+ * this helper with the byte offset of the packet payload that
+ * it wants to access; the helper will move *xdp_md*\ **->data**
+ * and *xdp_md *\ **->data_end** so they point to the requested
+ * payload offset and to the end of the fragment containing this
+ * byte offset, and return the byte offset of the start of the
+ * fragment.
+ * To move back to the beginning of the packet, simply call the
+ * helper with an offset of '0'.
+ * Note also that the helpers that modify the packet boundaries
+ * (*bpf_xdp_adjust_head()*, *bpf_xdp_adjust_tail()* and
+ * *bpf_xdp_adjust_meta()*) will fail if the pointers have been
+ * moved; it is the responsibility of the BPF program to move them
+ * back before using these helpers.
+ *
+ * A call to this helper is susceptible to change the underlying
+ * packet buffer. Therefore, at load time, all checks on pointers
+ * previously done by the verifier are invalidated and must be
+ * performed again, if the helper is used in combination with
+ * direct packet access.
+ * Return
+ * offset between the beginning of the current fragment and
+ * original *xdp_md*\ **->data** on success, or a negative error
+ * in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5055,6 +5086,7 @@ union bpf_attr { FN(get_func_ip), \ FN(get_attach_cookie), \ FN(xdp_get_buff_len), \+ FN(xdp_adjust_data), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -871,6 +873,12 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,if(ret)gotoout;+/* data pointers need to be reset after frag iteration */+if(unlikely(xdp.data_hard_start+xdp.mb.headroom!=xdp.data)){+ret=-EFAULT;+gotoout;+}+size=xdp.data_end-xdp.data_meta+sinfo->xdp_frags_size;ret=bpf_test_finish(kattr,uattr,xdp.data_meta,sinfo,size,retval,duration);
@@ -3827,6 +3827,10 @@ BPF_CALL_2(bpf_xdp_adjust_head, struct xdp_buff *, xdp, int, offset)void*data_start=xdp_frame_end+metalen;void*data=xdp->data+offset;+/* data pointers need to be reset after frag iteration */+if(unlikely(xdp->data_hard_start+xdp->mb.headroom!=xdp->data))+return-EINVAL;
-EFAULT? It might be nice if error code is different from below
for debugging?
ack, I will fix it in v13
quoted
+
if (unlikely(data < data_start ||
data > xdp->data_end - ETH_HLEN))
return -EINVAL;
Do we need to error this? If its not mb we can just return the same
as offset==0?
ack, we can check do something like:
u32 max_offset = xdp->mb.headlen;
if (xdp_buff_is_mb(xdp))
max_offset += sinfo->xdp_frags_size;
if (offset > max_offset)
return -EINVAL;
what do you think?
Regards,
Lorenzo
From: Lorenzo Bianconi <hidden> Date: 2021-09-07 08:35:53
Lorenzo Bianconi wrote:
quoted
This series introduce XDP multi-buffer support. The mvneta driver is
the first to support these new "non-linear" xdp_{buff,frame}. Reviewers
please focus on how these new types of xdp_{buff,frame} packets
traverse the different layers and the layout design. It is on purpose
that BPF-helpers are kept simple, as we don't want to expose the
internal layout to allow later changes.
The main idea for the new multi-buffer layout is to reuse the same
structure used for non-linear SKB. This rely on the "skb_shared_info"
struct at the end of the first buffer to link together subsequent
buffers. Keeping the layout compatible with SKBs is also done to ease
and speedup creating a SKB from an xdp_{buff,frame}.
Converting xdp_frame to SKB and deliver it to the network stack is shown
in patch 05/18 (e.g. cpumaps).
A multi-buffer bit (mb) has been introduced in the flags field of xdp_{buff,frame}
structure to notify the bpf/network layer if this is a xdp multi-buffer frame
(mb = 1) or not (mb = 0).
The mb bit will be set by a xdp multi-buffer capable driver only for
non-linear frames maintaining the capability to receive linear frames
without any extra cost since the skb_shared_info structure at the end
of the first buffer will be initialized only if mb is set.
Moreover the flags field in xdp_{buff,frame} will be reused even for
xdp rx csum offloading in future series.
The series is looking really close to me. Couple small comments/questions
inline. Also I think we should call out the potential issues in the cover
letter with regards to backwards compatibility. Something like,
"
A multi-buffer enabled NIC may receive XDP frames with multiple frags.
If a BPF program does not understand mb layouts its possible to contrive
a BPF program that incorrectly views data_end as the end of data when
there is more data in the payload. Note helpers will generally due the
correct thing, for example perf_output will consume entire payload. But,
it is still possible some programs could do the wrong thing even if in
an edge case. Although we expect most BPF programs not to be impacted
we can't rule out, you've been warned.
ack, I will add it to the cover letter in v13.
Regards,
Lorenzo
"
I can't think of an elegant way around this and it does require at least
some type of opt-in by increasing the MTU limit so I'm OK with it given
I think it should impact few (no?) real programs.
quoted
Typical use cases for this series are:
- Jumbo-frames
- Packet header split (please see Google���s use-case @ NetDevConf 0x14, [0])
- TSO/GRO
The two following ebpf helpers (and related selftests) has been introduced:
- bpf_xdp_adjust_data:
Move xdp_md->data and xdp_md->data_end pointers in subsequent fragments
according to the offset provided by the ebpf program. This helper can be
used to read/write values in frame payload.
- bpf_xdp_get_buff_len:
Return the total frame size (linear + paged parts)
bpf_xdp_adjust_tail and bpf_xdp_copy helpers have been modified to take into
account xdp multi-buff frames.
More info about the main idea behind this approach can be found here [1][2].
Changes since v11:
- add missing static to bpf_xdp_get_buff_len_proto structure
- fix bpf_xdp_adjust_data helper when offset is smaller than linear area length.
Changes since v10:
- move xdp->data to the requested payload offset instead of to the beginning of
the fragment in bpf_xdp_adjust_data()
Changes since v9:
- introduce bpf_xdp_adjust_data helper and related selftest
- add xdp_frags_size and xdp_frags_tsize fields in skb_shared_info
- introduce xdp_update_skb_shared_info utility routine in ordere to not reset
frags array in skb_shared_info converting from a xdp_buff/xdp_frame to a skb
- simplify bpf_xdp_copy routine
Changes since v8:
- add proper dma unmapping if XDP_TX fails on mvneta for a xdp multi-buff
- switch back to skb_shared_info implementation from previous xdp_shared_info
one
- avoid using a bietfield in xdp_buff/xdp_frame since it introduces performance
regressions. Tested now on 10G NIC (ixgbe) to verify there are no performance
penalties for regular codebase
- add bpf_xdp_get_buff_len helper and remove frame_length field in xdp ctx
- add data_len field in skb_shared_info struct
- introduce XDP_FLAGS_FRAGS_PF_MEMALLOC flag
Changes since v7:
- rebase on top of bpf-next
- fix sparse warnings
- improve comments for frame_length in include/net/xdp.h
Changes since v6:
- the main difference respect to previous versions is the new approach proposed
by Eelco to pass full length of the packet to eBPF layer in XDP context
- reintroduce multi-buff support to eBPF kself-tests
- reintroduce multi-buff support to bpf_xdp_adjust_tail helper
- introduce multi-buffer support to bpf_xdp_copy helper
- rebase on top of bpf-next
Changes since v5:
- rebase on top of bpf-next
- initialize mb bit in xdp_init_buff() and drop per-driver initialization
- drop xdp->mb initialization in xdp_convert_zc_to_xdp_frame()
- postpone introduction of frame_length field in XDP ctx to another series
- minor changes
Changes since v4:
- rebase ontop of bpf-next
- introduce xdp_shared_info to build xdp multi-buff instead of using the
skb_shared_info struct
- introduce frame_length in xdp ctx
- drop previous bpf helpers
- fix bpf_xdp_adjust_tail for xdp multi-buff
- introduce xdp multi-buff self-tests for bpf_xdp_adjust_tail
- fix xdp_return_frame_bulk for xdp multi-buff
Changes since v3:
- rebase ontop of bpf-next
- add patch 10/13 to copy back paged data from a xdp multi-buff frame to
userspace buffer for xdp multi-buff selftests
Changes since v2:
- add throughput measurements
- drop bpf_xdp_adjust_mb_header bpf helper
- introduce selftest for xdp multibuffer
- addressed comments on bpf_xdp_get_frags_count
- introduce xdp multi-buff support to cpumaps
Changes since v1:
- Fix use-after-free in xdp_return_{buff/frame}
- Introduce bpf helpers
- Introduce xdp_mb sample program
- access skb_shared_info->nr_frags only on the last fragment
Changes since RFC:
- squash multi-buffer bit initialization in a single patch
- add mvneta non-linear XDP buff support for tx side
[0] https://netdevconf.info/0x14/session.html?talk-the-path-to-tcp-4k-mtu-and-rx-zerocopy
[1] https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org
[2] https://netdevconf.info/0x14/session.html?tutorial-add-XDP-support-to-a-NIC-driver (XDPmulti-buffers section)
Eelco Chaudron (3):
bpf: add multi-buff support to the bpf_xdp_adjust_tail() API
bpf: add multi-buffer support to xdp copy helpers
bpf: update xdp_adjust_tail selftest to include multi-buffer
Lorenzo Bianconi (15):
net: skbuff: add size metadata to skb_shared_info for xdp
xdp: introduce flags field in xdp_buff/xdp_frame
net: mvneta: update mb bit before passing the xdp buffer to eBPF layer
net: mvneta: simplify mvneta_swbm_add_rx_fragment management
net: xdp: add xdp_update_skb_shared_info utility routine
net: marvell: rely on xdp_update_skb_shared_info utility routine
xdp: add multi-buff support to xdp_return_{buff/frame}
net: mvneta: add multi buffer support to XDP_TX
net: mvneta: enable jumbo frames for XDP
bpf: introduce bpf_xdp_get_buff_len helper
bpf: move user_size out of bpf_test_init
bpf: introduce multibuff support to bpf_prog_test_run_xdp()
bpf: test_run: add xdp_shared_info pointer in bpf_test_finish
signature
net: xdp: introduce bpf_xdp_adjust_data helper
bpf: add bpf_xdp_adjust_data selftest
drivers/net/ethernet/marvell/mvneta.c | 204 ++++++++++-------
include/linux/skbuff.h | 6 +-
include/net/xdp.h | 95 +++++++-
include/uapi/linux/bpf.h | 39 ++++
kernel/trace/bpf_trace.c | 3 +
net/bpf/test_run.c | 117 ++++++++--
net/core/filter.c | 213 +++++++++++++++++-
net/core/xdp.c | 76 ++++++-
tools/include/uapi/linux/bpf.h | 39 ++++
.../bpf/prog_tests/xdp_adjust_data.c | 55 +++++
.../bpf/prog_tests/xdp_adjust_tail.c | 118 ++++++++++
.../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 151 +++++++++----
.../bpf/progs/test_xdp_adjust_tail_grow.c | 10 +-
.../bpf/progs/test_xdp_adjust_tail_shrink.c | 32 ++-
.../selftests/bpf/progs/test_xdp_bpf2bpf.c | 2 +-
.../bpf/progs/test_xdp_update_frags.c | 41 ++++
16 files changed, 1036 insertions(+), 165 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_adjust_data.c
create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_update_frags.c
--
2.31.1