Merge branch 'bpf-xdp-offload-fixes'

Toke Høiland-Jørgensen says:

====================
This series restores the test_offload.py selftest to working order. It seems a
number of subtle behavioural changes have crept into various subsystems which
broke test_offload.py in a number of ways. Most of these are fairly benign
changes where small adjustments to the test script seems to be the best fix,
but one is an actual kernel bug that I've observed in the wild caused by a bad
interaction between xdp_attachment_flags_ok() and the rework of XDP program
handling in the core netdev code.

Patch 1 fixes the bug by removing xdp_attachment_flags_ok(), and the reminder of
the patches are adjustments to test_offload.py, including a new feature for
netdevsim to force a BPF verification fail. Please see the individual patches
for details.

Changelog:

v4:
  - Accidentally truncated the Fixes: hashes in patches 3/4 to 11 chars
v3:
  - Add Fixes: tags
v2:
  - Replace xdp_attachment_flags_ok() with a check in dev_xdp_attach()
  - Better packing of struct nsim_dev
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

4 files changed, 11 insertions, 14 deletions

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index b150da43adb2..437226866ce8 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -3562,9 +3562,6 @@ static int nfp_net_xdp_setup_drv(struct nfp_net *nn, struct netdev_bpf *bpf)
 	struct nfp_net_dp *dp;
 	int err;
 
-	if (!xdp_attachment_flags_ok(&nn->xdp, bpf))
-		return -EBUSY;
-
 	if (!prog == !nn->dp.xdp_prog) {
 		WRITE_ONCE(nn->dp.xdp_prog, prog);
 		xdp_attachment_setup(&nn->xdp, bpf);
@@ -3593,9 +3590,6 @@ static int nfp_net_xdp_setup_hw(struct nfp_net *nn, struct netdev_bpf *bpf)
 {
 	int err;
 
-	if (!xdp_attachment_flags_ok(&nn->xdp_hw, bpf))
-		return -EBUSY;
-
 	err = nfp_app_xdp_offload(nn->app, nn, bpf->prog, bpf->extack);
 	if (err)
 		return err;
diff --git a/drivers/net/ethernet/ti/cpsw_priv.c b/drivers/net/ethernet/ti/cpsw_priv.c
index 31c5e36ff706..424e644724e4 100644
--- a/drivers/net/ethernet/ti/cpsw_priv.c
+++ b/drivers/net/ethernet/ti/cpsw_priv.c
@@ -1265,9 +1265,6 @@ static int cpsw_xdp_prog_setup(struct cpsw_priv *priv, struct netdev_bpf *bpf)
 	if (!priv->xdpi.prog && !prog)
 		return 0;
 
-	if (!xdp_attachment_flags_ok(&priv->xdpi, bpf))
-		return -EBUSY;
-
 	WRITE_ONCE(priv->xdp_prog, prog);
 
 	xdp_attachment_setup(&priv->xdpi, bpf);
diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index 2e90512f3bbe..90aafb56f140 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -63,15 +63,20 @@ static int
 nsim_bpf_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn)
 {
 	struct nsim_bpf_bound_prog *state;
+	int ret = 0;
 
 	state = env->prog->aux->offload->dev_priv;
 	if (state->nsim_dev->bpf_bind_verifier_delay && !insn_idx)
 		msleep(state->nsim_dev->bpf_bind_verifier_delay);
 
-	if (insn_idx == env->prog->len - 1)
+	if (insn_idx == env->prog->len - 1) {
 		pr_vlog(env, "Hello from netdevsim!\n");
 
-	return 0;
+		if (!state->nsim_dev->bpf_bind_verifier_accept)
+			ret = -EOPNOTSUPP;
+	}
+
+	return ret;
 }
 
 static int nsim_bpf_finalize(struct bpf_verifier_env *env)
@@ -190,9 +195,6 @@ nsim_xdp_set_prog(struct netdevsim *ns, struct netdev_bpf *bpf,
 {
 	int err;
 
-	if (!xdp_attachment_flags_ok(xdp, bpf))
-		return -EBUSY;
-
 	if (bpf->command == XDP_SETUP_PROG && !ns->bpf_xdpdrv_accept) {
 		NSIM_EA(bpf->extack, "driver XDP disabled in DebugFS");
 		return -EOPNOTSUPP;
@@ -598,6 +600,9 @@ int nsim_bpf_dev_init(struct nsim_dev *nsim_dev)
 			    &nsim_dev->bpf_bind_accept);
 	debugfs_create_u32("bpf_bind_verifier_delay", 0600, nsim_dev->ddir,
 			   &nsim_dev->bpf_bind_verifier_delay);
+	nsim_dev->bpf_bind_verifier_accept = true;
+	debugfs_create_bool("bpf_bind_verifier_accept", 0600, nsim_dev->ddir,
+			    &nsim_dev->bpf_bind_verifier_accept);
 	return 0;
 }
 
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 827fc80f50a0..c4e7ad2a1964 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -189,6 +189,7 @@ struct nsim_dev {
 	struct dentry *take_snapshot;
 	struct bpf_offload_dev *bpf_dev;
 	bool bpf_bind_accept;
+	bool bpf_bind_verifier_accept;
 	u32 bpf_bind_verifier_delay;
 	struct dentry *ddir_bpf_bound_progs;
 	u32 prog_id_gen;