[PATCH bpf-next 0/2] nfp: bpf: add programmable RSS support

[PATCH bpf-next 0/2] nfp: bpf: add programmable RSS support

[Jakub Kicinski]

Hi!

This small series adds a feature which extends BPF offload beyond
a pure host processing offload and firmly into the realm of
heterogeneous processing.  Allowing offloaded XDP programs to set
the RX queue index opens the door for defining fully programmable
RSS/n-tuple filter replacement.  In fact the device datapath will
skip the RSS processing completely if BPF decided on the queue
already, making the XDP program replace part of the standard NIC
datapath.

We hope some day the entire NIC datapath will be defined by BPF :)

Jakub Kicinski (2):
  bpf: xdp: allow offloads to store into rx_queue_index
  nfp: bpf: support setting the RX queue index

 drivers/net/ethernet/netronome/nfp/bpf/fw.h   |  1 +
 drivers/net/ethernet/netronome/nfp/bpf/jit.c  | 47 +++++++++++++++++++
 drivers/net/ethernet/netronome/nfp/bpf/main.c | 11 +++++
 drivers/net/ethernet/netronome/nfp/bpf/main.h |  8 ++++
 .../net/ethernet/netronome/nfp/bpf/verifier.c | 28 ++++++++++-
 drivers/net/ethernet/netronome/nfp/nfp_asm.h  | 22 +++++----
 include/linux/bpf.h                           |  2 +-
 kernel/bpf/verifier.c                         |  2 +-
 net/core/filter.c                             |  9 +++-
 9 files changed, 115 insertions(+), 15 deletions(-)

-- 
2.17.0

[PATCH bpf-next 1/2] bpf: xdp: allow offloads to store into rx_queue_index

[Jakub Kicinski]

It's fairly easy for offloaded XDP programs to select the RX queue
packets go to.  We need a way of expressing this in the software.
Allow write to the rx_queue_index field of struct xdp_md for
device-bound programs.

Skip convert_ctx_access callback entirely for offloads.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
---
 include/linux/bpf.h   | 2 +-
 kernel/bpf/verifier.c | 2 +-
 net/core/filter.c     | 9 ++++++++-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 321969da67b7..a38e474bf7ee 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -627,7 +627,7 @@ bool bpf_offload_dev_match(struct bpf_prog *prog, struct bpf_map *map);
 #if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
 int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr);
 
-static inline bool bpf_prog_is_dev_bound(struct bpf_prog_aux *aux)
+static inline bool bpf_prog_is_dev_bound(const struct bpf_prog_aux *aux)
 {
 	return aux->offload_requested;
 }
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d5e1a6c4165d..d92d9c37affd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5215,7 +5215,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 		}
 	}
 
-	if (!ops->convert_ctx_access)
+	if (!ops->convert_ctx_access || bpf_prog_is_dev_bound(env->prog->aux))
 		return 0;
 
 	insn = env->prog->insnsi + delta;
diff --git a/net/core/filter.c b/net/core/filter.c
index cf0d27acf1d1..2336b90e8b26 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4911,8 +4911,15 @@ static bool xdp_is_valid_access(int off, int size,
 				const struct bpf_prog *prog,
 				struct bpf_insn_access_aux *info)
 {
-	if (type == BPF_WRITE)
+	if (type == BPF_WRITE) {
+		if (bpf_prog_is_dev_bound(prog->aux)) {
+			switch (off) {
+			case offsetof(struct xdp_md, rx_queue_index):
+				return __is_valid_xdp_access(off, size);
+			}
+		}
 		return false;
+	}
 
 	switch (off) {
 	case offsetof(struct xdp_md, data):
-- 
2.17.0

[PATCH bpf-next 2/2] nfp: bpf: support setting the RX queue index

[Jakub Kicinski]

BPF has access to all internal FW datapath structures.  Including
the structure containing RX queue selection.  With little coordination
with the datapath we can let the offloaded BPF select the RX queue.
We just need a way to tell the datapath that queue selection has already
been done and it shouldn't overwrite it.  Define a bit to tell datapath
BPF already selected a queue (QSEL_SET), if the selected queue is not
enabled (>= number of enabled queues) datapath will perform normal RSS.

BPF queue selection on the NIC can be used to replace standard
datapath RSS with fully programmable BPF/XDP RSS.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/fw.h   |  1 +
 drivers/net/ethernet/netronome/nfp/bpf/jit.c  | 47 +++++++++++++++++++
 drivers/net/ethernet/netronome/nfp/bpf/main.c | 11 +++++
 drivers/net/ethernet/netronome/nfp/bpf/main.h |  8 ++++
 .../net/ethernet/netronome/nfp/bpf/verifier.c | 28 ++++++++++-
 drivers/net/ethernet/netronome/nfp/nfp_asm.h  | 22 +++++----
 6 files changed, 105 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/fw.h b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
index 3dbc21653ce5..4c7972e3db63 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/fw.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/fw.h
@@ -50,6 +50,7 @@ enum bpf_cap_tlv_type {
 	NFP_BPF_CAP_TYPE_ADJUST_HEAD	= 2,
 	NFP_BPF_CAP_TYPE_MAPS		= 3,
 	NFP_BPF_CAP_TYPE_RANDOM		= 4,
+	NFP_BPF_CAP_TYPE_QUEUE_SELECT	= 5,
 };
 
 struct nfp_bpf_cap_tlv_func {
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 326a2085d650..a4d3da215863 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -42,6 +42,7 @@
 
 #include "main.h"
 #include "../nfp_asm.h"
+#include "../nfp_net_ctrl.h"
 
 /* --- NFP prog --- */
 /* Foreach "multiple" entries macros provide pos and next<n> pointers.
@@ -1470,6 +1471,38 @@ nfp_perf_event_output(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 	return 0;
 }
 
+static int
+nfp_queue_select(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
+{
+	u32 jmp_tgt;
+
+	jmp_tgt = nfp_prog_current_offset(nfp_prog) + 5;
+
+	/* Make sure the queue id fits into FW field */
+	emit_alu(nfp_prog, reg_none(), reg_a(meta->insn.src_reg * 2),
+		 ALU_OP_AND_NOT_B, reg_imm(0xff));
+	emit_br(nfp_prog, BR_BEQ, jmp_tgt, 2);
+
+	/* Set the 'queue selected' bit and the queue value */
+	emit_shf(nfp_prog, pv_qsel_set(nfp_prog),
+		 pv_qsel_set(nfp_prog), SHF_OP_OR, reg_imm(1),
+		 SHF_SC_L_SHF, PKT_VEL_QSEL_SET_BIT);
+	emit_ld_field(nfp_prog,
+		      pv_qsel_val(nfp_prog), 0x1, reg_b(meta->insn.src_reg * 2),
+		      SHF_SC_NONE, 0);
+	/* Delay slots end here, we will jump over next instruction if queue
+	 * value fits into the field.
+	 */
+	emit_ld_field(nfp_prog,
+		      pv_qsel_val(nfp_prog), 0x1, reg_imm(NFP_NET_RXR_MAX),
+		      SHF_SC_NONE, 0);
+
+	if (!nfp_prog_confirm_current_offset(nfp_prog, jmp_tgt))
+		return -EINVAL;
+
+	return 0;
+}
+
 /* --- Callbacks --- */
 static int mov_reg64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
@@ -2160,6 +2193,17 @@ mem_stx_stack(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 			    false, wrp_lmem_store);
 }
 
+static int mem_stx_xdp(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
+{
+	switch (meta->insn.off) {
+	case offsetof(struct xdp_md, rx_queue_index):
+		return nfp_queue_select(nfp_prog, meta);
+	}
+
+	WARN_ON_ONCE(1); /* verifier should have rejected bad accesses */
+	return -EOPNOTSUPP;
+}
+
 static int
 mem_stx(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 	unsigned int size)
@@ -2186,6 +2230,9 @@ static int mem_stx2(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int mem_stx4(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
+	if (meta->ptr.type == PTR_TO_CTX)
+		if (nfp_prog->type == BPF_PROG_TYPE_XDP)
+			return mem_stx_xdp(nfp_prog, meta);
 	return mem_stx(nfp_prog, meta, 4);
 }
 
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.c b/drivers/net/ethernet/netronome/nfp/bpf/main.c
index d72f9e7f42da..f1846d8f59cc 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.c
@@ -334,6 +334,13 @@ nfp_bpf_parse_cap_random(struct nfp_app_bpf *bpf, void __iomem *value,
 	return 0;
 }
 
+static int
+nfp_bpf_parse_cap_qsel(struct nfp_app_bpf *bpf, void __iomem *value, u32 length)
+{
+	bpf->queue_select = true;
+	return 0;
+}
+
 static int nfp_bpf_parse_capabilities(struct nfp_app *app)
 {
 	struct nfp_cpp *cpp = app->pf->cpp;
@@ -376,6 +383,10 @@ static int nfp_bpf_parse_capabilities(struct nfp_app *app)
 			if (nfp_bpf_parse_cap_random(app->priv, value, length))
 				goto err_release_free;
 			break;
+		case NFP_BPF_CAP_TYPE_QUEUE_SELECT:
+			if (nfp_bpf_parse_cap_qsel(app->priv, value, length))
+				goto err_release_free;
+			break;
 		default:
 			nfp_dbg(cpp, "unknown BPF capability: %d\n", type);
 			break;
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index 82682378d57f..8b143546ae85 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -82,10 +82,16 @@ enum static_regs {
 enum pkt_vec {
 	PKT_VEC_PKT_LEN		= 0,
 	PKT_VEC_PKT_PTR		= 2,
+	PKT_VEC_QSEL_SET	= 4,
+	PKT_VEC_QSEL_VAL	= 6,
 };
 
+#define PKT_VEL_QSEL_SET_BIT	4
+
 #define pv_len(np)	reg_lm(1, PKT_VEC_PKT_LEN)
 #define pv_ctm_ptr(np)	reg_lm(1, PKT_VEC_PKT_PTR)
+#define pv_qsel_set(np)	reg_lm(1, PKT_VEC_QSEL_SET)
+#define pv_qsel_val(np)	reg_lm(1, PKT_VEC_QSEL_VAL)
 
 #define stack_reg(np)	reg_a(STATIC_REG_STACK)
 #define stack_imm(np)	imm_b(np)
@@ -139,6 +145,7 @@ enum pkt_vec {
  * @helpers.perf_event_output:	output perf event to a ring buffer
  *
  * @pseudo_random:	FW initialized the pseudo-random machinery (CSRs)
+ * @queue_select:	BPF can set the RX queue ID in packet vector
  */
 struct nfp_app_bpf {
 	struct nfp_app *app;
@@ -181,6 +188,7 @@ struct nfp_app_bpf {
 	} helpers;
 
 	bool pseudo_random;
+	bool queue_select;
 };
 
 enum nfp_bpf_map_use {
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
index e163f3cfa47d..844a9be6e55a 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
@@ -467,6 +467,30 @@ nfp_bpf_check_ptr(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 	return 0;
 }
 
+static int
+nfp_bpf_check_store(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
+		    struct bpf_verifier_env *env)
+{
+	const struct bpf_reg_state *reg = cur_regs(env) + meta->insn.dst_reg;
+
+	if (reg->type == PTR_TO_CTX) {
+		if (nfp_prog->type == BPF_PROG_TYPE_XDP) {
+			/* XDP ctx accesses must be 4B in size */
+			switch (meta->insn.off) {
+			case offsetof(struct xdp_md, rx_queue_index):
+				if (nfp_prog->bpf->queue_select)
+					goto exit_check_ptr;
+				pr_vlog(env, "queue selection not supported by FW\n");
+				return -EOPNOTSUPP;
+			}
+		}
+		pr_vlog(env, "unsupported store to context field\n");
+		return -EOPNOTSUPP;
+	}
+exit_check_ptr:
+	return nfp_bpf_check_ptr(nfp_prog, meta, env, meta->insn.dst_reg);
+}
+
 static int
 nfp_bpf_check_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 		   struct bpf_verifier_env *env)
@@ -522,8 +546,8 @@ nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
 		return nfp_bpf_check_ptr(nfp_prog, meta, env,
 					 meta->insn.src_reg);
 	if (is_mbpf_store(meta))
-		return nfp_bpf_check_ptr(nfp_prog, meta, env,
-					 meta->insn.dst_reg);
+		return nfp_bpf_check_store(nfp_prog, meta, env);
+
 	if (is_mbpf_xadd(meta))
 		return nfp_bpf_check_xadd(nfp_prog, meta, env);
 
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.h b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
index 5f2b2f24f4fa..faa4e131c136 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_asm.h
+++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
@@ -183,16 +183,18 @@ enum shf_sc {
 #define OP_ALU_DST_LMEXTN	0x80000000000ULL
 
 enum alu_op {
-	ALU_OP_NONE	= 0x00,
-	ALU_OP_ADD	= 0x01,
-	ALU_OP_NOT	= 0x04,
-	ALU_OP_ADD_2B	= 0x05,
-	ALU_OP_AND	= 0x08,
-	ALU_OP_SUB_C	= 0x0d,
-	ALU_OP_ADD_C	= 0x11,
-	ALU_OP_OR	= 0x14,
-	ALU_OP_SUB	= 0x15,
-	ALU_OP_XOR	= 0x18,
+	ALU_OP_NONE		= 0x00,
+	ALU_OP_ADD		= 0x01,
+	ALU_OP_NOT		= 0x04,
+	ALU_OP_ADD_2B		= 0x05,
+	ALU_OP_AND		= 0x08,
+	ALU_OP_AND_NOT_A	= 0x0c,
+	ALU_OP_SUB_C		= 0x0d,
+	ALU_OP_AND_NOT_B	= 0x10,
+	ALU_OP_ADD_C		= 0x11,
+	ALU_OP_OR		= 0x14,
+	ALU_OP_SUB		= 0x15,
+	ALU_OP_XOR		= 0x18,
 };
 
 enum alu_dst_ab {
-- 
2.17.0

Re: [PATCH bpf-next 0/2] nfp: bpf: add programmable RSS support

[Alexei Starovoitov]

On Tue, May 08, 2018 at 07:37:05PM -0700, Jakub Kicinski wrote:
> Hi!
> 
> This small series adds a feature which extends BPF offload beyond
> a pure host processing offload and firmly into the realm of
> heterogeneous processing.  Allowing offloaded XDP programs to set
> the RX queue index opens the door for defining fully programmable
> RSS/n-tuple filter replacement.  In fact the device datapath will
> skip the RSS processing completely if BPF decided on the queue
> already, making the XDP program replace part of the standard NIC
> datapath.

Absolutely love it!
Huge feature enabled by such tiny diff.

For the set:
Acked-by: Alexei Starovoitov <ast@kernel.org>

Re: [PATCH bpf-next 0/2] nfp: bpf: add programmable RSS support

[Daniel Borkmann]

On 05/09/2018 04:42 AM, Alexei Starovoitov wrote:
> On Tue, May 08, 2018 at 07:37:05PM -0700, Jakub Kicinski wrote:
>> Hi!
>>
>> This small series adds a feature which extends BPF offload beyond
>> a pure host processing offload and firmly into the realm of
>> heterogeneous processing.  Allowing offloaded XDP programs to set
>> the RX queue index opens the door for defining fully programmable
>> RSS/n-tuple filter replacement.  In fact the device datapath will
>> skip the RSS processing completely if BPF decided on the queue
>> already, making the XDP program replace part of the standard NIC
>> datapath.
> 
> Absolutely love it!
> Huge feature enabled by such tiny diff.
> 
> For the set:
> Acked-by: Alexei Starovoitov <ast@kernel.org>

Second that! Applied to bpf-next, thanks Jakub!