xsk: Add option to calculate TX checksum in SW

For XDP_COPY mode, add a UMEM option XDP_UMEM_TX_SW_CSUM to call skb_checksum_help in transmit path. Might be useful to debugging issues with real hardware. I also use this mode in the selftests.

Stanislav Fomichev committed 2 years ago

Commit 11614721 parent ce59f967 files · +37 −3Browse files

Unified · Split

7 files

Documentation/networking/xsk-tx-metadata.rst +9 −0
include/net/xsk_buff_pool.h +1 −0
include/uapi/linux/if_xdp.h +7 −1
net/xdp/xdp_umem.c +6 −1
net/xdp/xsk.c +6 −0
net/xdp/xsk_buff_pool.c +1 −0
tools/include/uapi/linux/if_xdp.h +7 −1

Documentation/networking/xsk-tx-metadata.rst+9−0

@@ -50,6 +50,15 @@ packet's ``struct xdp_desc`` descriptor should set ``XDP_TX_METADATA`` · 49 unmodified lines
50	50	bit in the ``options`` field. Also note that in a multi-buffer packet
51	51	only the first chunk should carry the metadata.
52	52
	53	+Software TX Checksum
	54	+====================
	55	+
	56	+For development and testing purposes its possible to pass
	57	+``XDP_UMEM_TX_SW_CSUM`` flag to ``XDP_UMEM_REG`` UMEM registration call.
	58	+In this case, when running in ``XDK_COPY`` mode, the TX checksum
	59	+is calculated on the CPU. Do not enable this option in production because
	60	+it will negatively affect performance.
	61	+
53	62	Querying Device Capabilities
54	63	============================
55	64

include/net/xsk_buff_pool.h+1−0

@@ -83,6 +83,7 @@ struct xsk_buff_pool { · 82 unmodified lines
83	83	bool uses_need_wakeup;
84	84	bool dma_need_sync;
85	85	bool unaligned;
	86	+ bool tx_sw_csum;
86	87	void *addrs;
87	88	/* Mutual exclusion of the completion ring in the SKB mode. Two cases to protect:
88	89	* NAPI TX thread and sendmsg error paths in the SKB destructor callback and when

include/uapi/linux/if_xdp.h+7−1

@@ -33,7 +33,13 @@ · 32 unmodified lines
33	33	#define XDP_USE_SG (1 << 4)
34	34
35	35	/* Flags for xsk_umem_config flags */
36		−#define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << 0)
	36	+#define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << 0)
	37	+
	38	+/* Force checksum calculation in software. Can be used for testing or
	39	+ * working around potential HW issues. This option causes performance
	40	+ * degradation and only works in XDP_COPY mode.
	41	+ */
	42	+#define XDP_UMEM_TX_SW_CSUM (1 << 1)
37	43
38	44	struct sockaddr_xdp {
39	45	__u16 sxdp_family;

net/xdp/xdp_umem.c+6−1

@@ -148,6 +148,11 @@ static int xdp_umem_account_pages(struct xdp_umem *umem) · 147 unmodified lines
148	148	return 0;
149	149	}
150	150
	151	+#define XDP_UMEM_FLAGS_VALID ( \
	152	+ XDP_UMEM_UNALIGNED_CHUNK_FLAG \| \
	153	+ XDP_UMEM_TX_SW_CSUM \| \
	154	+ 0)
	155	+
151	156	static int xdp_umem_reg(struct xdp_umem umem, struct xdp_umem_reg mr)
152	157	{
153	158	bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
@@ -167,7 +172,7 @@ static int xdp_umem_reg(struct xdp_umem umem, struct xdp_umem_reg mr) · 13 unmodified lines
167	172	return -EINVAL;
168	173	}
169	174
170		− if (mr->flags & ~XDP_UMEM_UNALIGNED_CHUNK_FLAG)
	175	+ if (mr->flags & ~XDP_UMEM_FLAGS_VALID)
171	176	return -EINVAL;
172	177
173	178	if (!unaligned_chunks && !is_power_of_2(chunk_size))

net/xdp/xsk.c+6−0

@@ -744,6 +744,12 @@ static struct sk_buff xsk_build_skb(struct xdp_sock xs, · 743 unmodified lines
744	744	skb->csum_start = hr + meta->request.csum_start;
745	745	skb->csum_offset = meta->request.csum_offset;
746	746	skb->ip_summed = CHECKSUM_PARTIAL;
	747	+
	748	+ if (unlikely(xs->pool->tx_sw_csum)) {
	749	+ err = skb_checksum_help(skb);
	750	+ if (err)
	751	+ goto free_err;
	752	+ }
747	753	}
748	754	}
749	755	}

net/xdp/xsk_buff_pool.c+1−0

@@ -86,6 +86,7 @@ struct xsk_buff_pool xp_create_and_assign_umem(struct xdp_sock xs, · 85 unmodified lines
86	86	pool->umem = umem;
87	87	pool->addrs = umem->addrs;
88	88	pool->tx_metadata_len = umem->tx_metadata_len;
	89	+ pool->tx_sw_csum = umem->flags & XDP_UMEM_TX_SW_CSUM;
89	90	INIT_LIST_HEAD(&pool->free_list);
90	91	INIT_LIST_HEAD(&pool->xskb_list);
91	92	INIT_LIST_HEAD(&pool->xsk_tx_list);

tools/include/uapi/linux/if_xdp.h+7−1

@@ -33,7 +33,13 @@ · 32 unmodified lines
33	33	#define XDP_USE_SG (1 << 4)
34	34
35	35	/* Flags for xsk_umem_config flags */
36		−#define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << 0)
	36	+#define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << 0)
	37	+
	38	+/* Force checksum calculation in software. Can be used for testing or
	39	+ * working around potential HW issues. This option causes performance
	40	+ * degradation and only works in XDP_COPY mode.
	41	+ */
	42	+#define XDP_UMEM_TX_SW_CSUM (1 << 1)
37	43
38	44	struct sockaddr_xdp {
39	45	__u16 sxdp_family;

xsk: Add option to calculate TX checksum in SW

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