net/mlx5: Handle pairing of E-switch via uplink un/load APIs

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: Handle pairing of E-switch via uplink un/load APIs

In case user switch a device from switchdev mode to legacy mode, mlx5

first unpair the E-switch and afterwards unload the uplink vport.

From the other hand, in case user remove or reload a device, mlx5

first unload the uplink vport and afterwards unpair the E-switch.

The latter is causing a bug[1], hence, handle pairing of E-switch as

part of uplink un/load APIs.

[1]

In case VF_LAG is used, every tc fdb flow is duplicated to the peer

esw. However, the original esw keeps a pointer to this duplicated

flow, not the peer esw.

e.g.: if user create tc fdb flow over esw0, the flow is duplicated

over esw1, in FW/HW, but in SW, esw0 keeps a pointer to the duplicated

flow.

During module unload while a peer tc fdb flow is still offloaded, in

case the first device to be removed is the peer device (esw1 in the

example above), the peer net-dev is destroyed, and so the mlx5e_priv

is memset to 0.

Afterwards, the peer device is trying to unpair himself from the

original device (esw0 in the example above). Unpair API invoke the

original device to clear peer flow from its eswitch (esw0), but the

peer flow, which is stored over the original eswitch (esw0), is

trying to use the peer mlx5e_priv, which is memset to 0 and result in

bellow kernel-oops.

[ 157.964081 ] BUG: unable to handle page fault for address: 000000000002ce60

[ 157.964662 ] #PF: supervisor read access in kernel mode

[ 157.965123 ] #PF: error_code(0x0000) - not-present page

[ 157.965582 ] PGD 0 P4D 0

[ 157.965866 ] Oops: 0000 [#1] SMP

[ 157.967670 ] RIP: 0010:mlx5e_tc_del_fdb_flow+0x48/0x460 [mlx5_core]

[ 157.976164 ] Call Trace:

[ 157.976437 ] <TASK>

[ 157.976690 ] __mlx5e_tc_del_fdb_peer_flow+0xe6/0x100 [mlx5_core]

[ 157.977230 ] mlx5e_tc_clean_fdb_peer_flows+0x67/0x90 [mlx5_core]

[ 157.977767 ] mlx5_esw_offloads_unpair+0x2d/0x1e0 [mlx5_core]

[ 157.984653 ] mlx5_esw_offloads_devcom_event+0xbf/0x130 [mlx5_core]

[ 157.985212 ] mlx5_devcom_send_event+0xa3/0xb0 [mlx5_core]

[ 157.985714 ] esw_offloads_disable+0x5a/0x110 [mlx5_core]

[ 157.986209 ] mlx5_eswitch_disable_locked+0x152/0x170 [mlx5_core]

[ 157.986757 ] mlx5_eswitch_disable+0x51/0x80 [mlx5_core]

[ 157.987248 ] mlx5_unload+0x2a/0xb0 [mlx5_core]

[ 157.987678 ] mlx5_uninit_one+0x5f/0xd0 [mlx5_core]

[ 157.988127 ] remove_one+0x64/0xe0 [mlx5_core]

[ 157.988549 ] pci_device_remove+0x31/0xa0

[ 157.988933 ] device_release_driver_internal+0x18f/0x1f0

[ 157.989402 ] driver_detach+0x3f/0x80

[ 157.989754 ] bus_remove_driver+0x70/0xf0

[ 157.990129 ] pci_unregister_driver+0x34/0x90

[ 157.990537 ] mlx5_cleanup+0xc/0x1c [mlx5_core]

[ 157.990972 ] __x64_sys_delete_module+0x15a/0x250

[ 157.991398 ] ? exit_to_user_mode_prepare+0xea/0x110

[ 157.991840 ] do_syscall_64+0x3d/0x90

[ 157.992198 ] entry_SYSCALL_64_after_hwframe+0x46/0xb0