[PATCH net] net: enetc: prevent VF from configuring preemptiable TCs

[Wei Fang <wei.fang@nxp.com>]

Both ENETC PF and VF drivers share enetc_setup_tc_mqprio() to configure
MQPRIO. And enetc_setup_tc_mqprio() calls enetc_change_preemptible_tcs()
to configure preemptible TCs. However, only PF is able to configure
preemptible TCs. Because only PF has related registers, while VF does not
have these registers. So for VF, its hw->port pointer is NULL. Therefore,
VF will access an invalid pointer when accessing a non-existent register,
which will cause a call trace issue. The call trace log is shown below.

root@ls1028ardb:~# tc qdisc add dev eno0vf0 parent root handle 100: \
mqprio num_tc 4 map 0 0 1 1 2 2 3 3 queues 1@0 1@1 1@2 1@3 hw 1
[  187.290775] Unable to handle kernel paging request at virtual address 0000000000001f00
[  187.298760] Mem abort info:
[  187.301607]   ESR = 0x0000000096000004
[  187.305373]   EC = 0x25: DABT (current EL), IL = 32 bits
[  187.310714]   SET = 0, FnV = 0
[  187.313778]   EA = 0, S1PTW = 0
[  187.316923]   FSC = 0x04: level 0 translation fault
[  187.321818] Data abort info:
[  187.324701]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[  187.330207]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[  187.335278]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[  187.340610] user pgtable: 4k pages, 48-bit VAs, pgdp=0000002084b71000
[  187.347076] [0000000000001f00] pgd=0000000000000000, p4d=0000000000000000
[  187.353900] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[  187.360188] Modules linked in: xt_conntrack xt_addrtype cfg80211 rfkill snd_soc_hdmi_codec fsl_jr_uio caam_jr caamkeyblob_desc caamhash_desc caamalg_descp
[  187.406320] CPU: 0 PID: 1117 Comm: tc Not tainted 6.6.52-gfbb48d8e2ddb #1
[  187.413131] Hardware name: LS1028A RDB Board (DT)
[  187.417846] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[  187.424831] pc : enetc_mm_commit_preemptible_tcs+0x1c4/0x400
[  187.430518] lr : enetc_mm_commit_preemptible_tcs+0x30c/0x400
[  187.436195] sp : ffff800084a4b400
[  187.439515] x29: ffff800084a4b400 x28: 0000000000000004 x27: ffff6a58c5229808
[  187.446679] x26: 0000000080000203 x25: ffff800085218600 x24: 0000000000000004
[  187.453842] x23: ffff6a58c42e4a00 x22: ffff6a58c5229808 x21: ffff6a58c42e4980
[  187.461004] x20: ffff6a58c5229800 x19: 0000000000001f00 x18: 0000000000000001
[  187.468167] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[  187.475328] x14: 00000000000003f8 x13: 0000000000000400 x12: 0000000000065feb
[  187.482491] x11: 0000000000000000 x10: ffff6a593f6f9918 x9 : 0000000000000000
[  187.489653] x8 : ffff800084a4b668 x7 : 0000000000000003 x6 : 0000000000000001
[  187.496815] x5 : 0000000000001f00 x4 : 0000000000000000 x3 : 0000000000000000
[  187.503977] x2 : 0000000000000000 x1 : 0000000000000200 x0 : ffffd2fbd8497460
[  187.511140] Call trace:
[  187.513588]  enetc_mm_commit_preemptible_tcs+0x1c4/0x400
[  187.518918]  enetc_setup_tc_mqprio+0x180/0x214
[  187.523374]  enetc_vf_setup_tc+0x1c/0x30
[  187.527306]  mqprio_enable_offload+0x144/0x178
[  187.531766]  mqprio_init+0x3ec/0x668
[  187.535351]  qdisc_create+0x15c/0x488
[  187.539023]  tc_modify_qdisc+0x398/0x73c
[  187.542958]  rtnetlink_rcv_msg+0x128/0x378
[  187.547064]  netlink_rcv_skb+0x60/0x130
[  187.550910]  rtnetlink_rcv+0x18/0x24
[  187.554492]  netlink_unicast+0x300/0x36c
[  187.558425]  netlink_sendmsg+0x1a8/0x420
[  187.562358]  ____sys_sendmsg+0x214/0x26c
[  187.566292]  ___sys_sendmsg+0xb0/0x108
[  187.570050]  __sys_sendmsg+0x88/0xe8
[  187.573634]  __arm64_sys_sendmsg+0x24/0x30
[  187.577742]  invoke_syscall+0x48/0x114
[  187.581503]  el0_svc_common.constprop.0+0x40/0xe0
[  187.586222]  do_el0_svc+0x1c/0x28
[  187.589544]  el0_svc+0x40/0xe4
[  187.592607]  el0t_64_sync_handler+0x120/0x12c
[  187.596976]  el0t_64_sync+0x190/0x194
[  187.600648] Code: d65f03c0 d283e005 8b050273 14000050 (b9400273)
[  187.606759] ---[ end trace 0000000000000000 ]---

Fixes: 827145392a4a ("net: enetc: only commit preemptible TCs to hardware when MM TX is active")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
 drivers/net/ethernet/freescale/enetc/enetc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index c09370eab319..c9f7b7b4445f 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -28,6 +28,9 @@ EXPORT_SYMBOL_GPL(enetc_port_mac_wr);
 static void enetc_change_preemptible_tcs(struct enetc_ndev_priv *priv,
 					 u8 preemptible_tcs)
 {
+	if (!enetc_si_is_pf(priv->si))
+		return;
+
 	priv->preemptible_tcs = preemptible_tcs;
 	enetc_mm_commit_preemptible_tcs(priv);
 }
-- 
2.34.1