[PATCH net 0/2][pull request] Intel Wired LAN Driver Updates 2021-11-22

[PATCH net 0/2][pull request] Intel Wired LAN Driver Updates 2021-11-22

[Tony Nguyen]

Maciej Fijalkowski says:

Here are the two fixes for issues around ethtool's set_channels()
callback for ice driver. Both are related to XDP resources. First one
corrects the size of vsi->txq_map that is used to track the usage of Tx
resources and the second one prevents the wrong refcounting of bpf_prog.

The following are changes since commit a68229ca634066975fff6d4780155bd2eb14a82a:
  nixge: fix mac address error handling again
and are available in the git repository at:
  git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue 100GbE

Maciej Fijalkowski (1):
  ice: fix vsi->txq_map sizing

Marta Plantykow (1):
  ice: avoid bpf_prog refcount underflow

 drivers/net/ethernet/intel/ice/ice_lib.c  |  9 +++++++--
 drivers/net/ethernet/intel/ice/ice_main.c | 18 +++++++++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

-- 
2.31.1

[PATCH net 1/2] ice: fix vsi->txq_map sizing

[Tony Nguyen]

From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

The approach of having XDP queue per CPU regardless of user's setting
exposed a hidden bug that could occur in case when Rx queue count differ
from Tx queue count. Currently vsi->txq_map's size is equal to the
doubled vsi->alloc_txq, which is not correct due to the fact that XDP
rings were previously based on the Rx queue count. Below splat can be
seen when ethtool -L is used and XDP rings are configured:

[  682.875339] BUG: kernel NULL pointer dereference, address: 000000000000000f
[  682.883403] #PF: supervisor read access in kernel mode
[  682.889345] #PF: error_code(0x0000) - not-present page
[  682.895289] PGD 0 P4D 0
[  682.898218] Oops: 0000 [#1] PREEMPT SMP PTI
[  682.903055] CPU: 42 PID: 2878 Comm: ethtool Tainted: G           OE     5.15.0-rc5+ #1
[  682.912214] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS GRRFCRB1.86B.0276.D07.1605190235 05/19/2016
[  682.923380] RIP: 0010:devres_remove+0x44/0x130
[  682.928527] Code: 49 89 f4 55 48 89 fd 4c 89 ff 53 48 83 ec 10 e8 92 b9 49 00 48 8b 9d a8 02 00 00 48 8d 8d a0 02 00 00 49 89 c2 48 39 cb 74 0f <4c> 3b 63 10 74 25 48 8b 5b 08 48 39 cb 75 f1 4c 89 ff 4c 89 d6 e8
[  682.950237] RSP: 0018:ffffc90006a679f0 EFLAGS: 00010002
[  682.956285] RAX: 0000000000000286 RBX: ffffffffffffffff RCX: ffff88908343a370
[  682.964538] RDX: 0000000000000001 RSI: ffffffff81690d60 RDI: 0000000000000000
[  682.972789] RBP: ffff88908343a0d0 R08: 0000000000000000 R09: 0000000000000000
[  682.981040] R10: 0000000000000286 R11: 3fffffffffffffff R12: ffffffff81690d60
[  682.989282] R13: ffffffff81690a00 R14: ffff8890819807a8 R15: ffff88908343a36c
[  682.997535] FS:  00007f08c7bfa740(0000) GS:ffff88a03fd00000(0000) knlGS:0000000000000000
[  683.006910] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  683.013557] CR2: 000000000000000f CR3: 0000001080a66003 CR4: 00000000003706e0
[  683.021819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  683.030075] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  683.038336] Call Trace:
[  683.041167]  devm_kfree+0x33/0x50
[  683.045004]  ice_vsi_free_arrays+0x5e/0xc0 [ice]
[  683.050380]  ice_vsi_rebuild+0x4c8/0x750 [ice]
[  683.055543]  ice_vsi_recfg_qs+0x9a/0x110 [ice]
[  683.060697]  ice_set_channels+0x14f/0x290 [ice]
[  683.065962]  ethnl_set_channels+0x333/0x3f0
[  683.070807]  genl_family_rcv_msg_doit+0xea/0x150
[  683.076152]  genl_rcv_msg+0xde/0x1d0
[  683.080289]  ? channels_prepare_data+0x60/0x60
[  683.085432]  ? genl_get_cmd+0xd0/0xd0
[  683.089667]  netlink_rcv_skb+0x50/0xf0
[  683.094006]  genl_rcv+0x24/0x40
[  683.097638]  netlink_unicast+0x239/0x340
[  683.102177]  netlink_sendmsg+0x22e/0x470
[  683.106717]  sock_sendmsg+0x5e/0x60
[  683.110756]  __sys_sendto+0xee/0x150
[  683.114894]  ? handle_mm_fault+0xd0/0x2a0
[  683.119535]  ? do_user_addr_fault+0x1f3/0x690
[  683.134173]  __x64_sys_sendto+0x25/0x30
[  683.148231]  do_syscall_64+0x3b/0xc0
[  683.161992]  entry_SYSCALL_64_after_hwframe+0x44/0xae

Fix this by taking into account the value that num_possible_cpus()
yields in addition to vsi->alloc_txq instead of doubling the latter.

Fixes: efc2214b6047 ("ice: Add support for XDP")
Fixes: 22bf877e528f ("ice: introduce XDP_TX fallback path")
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Kiran Bhandare <kiranx.bhandare@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_lib.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
index 40562600a8cf..09a3297cd63c 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_lib.c
@@ -89,8 +89,13 @@ static int ice_vsi_alloc_arrays(struct ice_vsi *vsi)
 	if (!vsi->rx_rings)
 		goto err_rings;
 
-	/* XDP will have vsi->alloc_txq Tx queues as well, so double the size */
-	vsi->txq_map = devm_kcalloc(dev, (2 * vsi->alloc_txq),
+	/* txq_map needs to have enough space to track both Tx (stack) rings
+	 * and XDP rings; at this point vsi->num_xdp_txq might not be set,
+	 * so use num_possible_cpus() as we want to always provide XDP ring
+	 * per CPU, regardless of queue count settings from user that might
+	 * have come from ethtool's set_channels() callback;
+	 */
+	vsi->txq_map = devm_kcalloc(dev, (vsi->alloc_txq + num_possible_cpus()),
 				    sizeof(*vsi->txq_map), GFP_KERNEL);
 
 	if (!vsi->txq_map)
-- 
2.31.1

[PATCH net 2/2] ice: avoid bpf_prog refcount underflow

[Tony Nguyen]

From: Marta Plantykow <marta.a.plantykow@intel.com>

Ice driver has the routines for managing XDP resources that are shared
between ndo_bpf op and VSI rebuild flow. The latter takes place for
example when user changes queue count on an interface via ethtool's
set_channels().

There is an issue around the bpf_prog refcounting when VSI is being
rebuilt - since ice_prepare_xdp_rings() is called with vsi->xdp_prog as
an argument that is used later on by ice_vsi_assign_bpf_prog(), same
bpf_prog pointers are swapped with each other. Then it is also
interpreted as an 'old_prog' which in turn causes us to call
bpf_prog_put on it that will decrement its refcount.

Below splat can be interpreted in a way that due to zero refcount of a
bpf_prog it is wiped out from the system while kernel still tries to
refer to it:

[  481.069429] BUG: unable to handle page fault for address: ffffc9000640f038
[  481.077390] #PF: supervisor read access in kernel mode
[  481.083335] #PF: error_code(0x0000) - not-present page
[  481.089276] PGD 100000067 P4D 100000067 PUD 1001cb067 PMD 106d2b067 PTE 0
[  481.097141] Oops: 0000 [#1] PREEMPT SMP PTI
[  481.101980] CPU: 12 PID: 3339 Comm: sudo Tainted: G           OE     5.15.0-rc5+ #1
[  481.110840] Hardware name: Intel Corp. GRANTLEY/GRANTLEY, BIOS GRRFCRB1.86B.0276.D07.1605190235 05/19/2016
[  481.122021] RIP: 0010:dev_xdp_prog_id+0x25/0x40
[  481.127265] Code: 80 00 00 00 00 0f 1f 44 00 00 89 f6 48 c1 e6 04 48 01 fe 48 8b 86 98 08 00 00 48 85 c0 74 13 48 8b 50 18 31 c0 48 85 d2 74 07 <48> 8b 42 38 8b 40 20 c3 48 8b 96 90 08 00 00 eb e8 66 2e 0f 1f 84
[  481.148991] RSP: 0018:ffffc90007b63868 EFLAGS: 00010286
[  481.155034] RAX: 0000000000000000 RBX: ffff889080824000 RCX: 0000000000000000
[  481.163278] RDX: ffffc9000640f000 RSI: ffff889080824010 RDI: ffff889080824000
[  481.171527] RBP: ffff888107af7d00 R08: 0000000000000000 R09: ffff88810db5f6e0
[  481.179776] R10: 0000000000000000 R11: ffff8890885b9988 R12: ffff88810db5f4bc
[  481.188026] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[  481.196276] FS:  00007f5466d5bec0(0000) GS:ffff88903fb00000(0000) knlGS:0000000000000000
[  481.205633] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  481.212279] CR2: ffffc9000640f038 CR3: 000000014429c006 CR4: 00000000003706e0
[  481.220530] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  481.228771] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  481.237029] Call Trace:
[  481.239856]  rtnl_fill_ifinfo+0x768/0x12e0
[  481.244602]  rtnl_dump_ifinfo+0x525/0x650
[  481.249246]  ? __alloc_skb+0xa5/0x280
[  481.253484]  netlink_dump+0x168/0x3c0
[  481.257725]  netlink_recvmsg+0x21e/0x3e0
[  481.262263]  ____sys_recvmsg+0x87/0x170
[  481.266707]  ? __might_fault+0x20/0x30
[  481.271046]  ? _copy_from_user+0x66/0xa0
[  481.275591]  ? iovec_from_user+0xf6/0x1c0
[  481.280226]  ___sys_recvmsg+0x82/0x100
[  481.284566]  ? sock_sendmsg+0x5e/0x60
[  481.288791]  ? __sys_sendto+0xee/0x150
[  481.293129]  __sys_recvmsg+0x56/0xa0
[  481.297267]  do_syscall_64+0x3b/0xc0
[  481.301395]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  481.307238] RIP: 0033:0x7f5466f39617
[  481.311373] Code: 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb bd 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2f 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
[  481.342944] RSP: 002b:00007ffedc7f4308 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
[  481.361783] RAX: ffffffffffffffda RBX: 00007ffedc7f5460 RCX: 00007f5466f39617
[  481.380278] RDX: 0000000000000000 RSI: 00007ffedc7f5360 RDI: 0000000000000003
[  481.398500] RBP: 00007ffedc7f53f0 R08: 0000000000000000 R09: 000055d556f04d50
[  481.416463] R10: 0000000000000077 R11: 0000000000000246 R12: 00007ffedc7f5360
[  481.434131] R13: 00007ffedc7f5350 R14: 00007ffedc7f5344 R15: 0000000000000e98
[  481.451520] Modules linked in: ice(OE) af_packet binfmt_misc nls_iso8859_1 ipmi_ssif intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp mxm_wmi mei_me coretemp mei ipmi_si ipmi_msghandler wmi acpi_pad acpi_power_meter ip_tables x_tables autofs4 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel ahci crypto_simd cryptd libahci lpc_ich [last unloaded: ice]
[  481.528558] CR2: ffffc9000640f038
[  481.542041] ---[ end trace d1f24c9ecf5b61c1 ]---

Fix this by only calling ice_vsi_assign_bpf_prog() inside
ice_prepare_xdp_rings() when current vsi->xdp_prog pointer is NULL.
This way set_channels() flow will not attempt to swap the vsi->xdp_prog
pointers with itself.

Also, sprinkle around some comments that provide a reasoning about
correlation between driver and kernel in terms of bpf_prog refcount.

Fixes: efc2214b6047 ("ice: Add support for XDP")
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Marta Plantykow <marta.a.plantykow@intel.com>
Co-developed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Kiran Bhandare <kiranx.bhandare@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_main.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index f099797f35e3..4d1fc48c9744 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -2609,7 +2609,18 @@ int ice_prepare_xdp_rings(struct ice_vsi *vsi, struct bpf_prog *prog)
 			ice_stat_str(status));
 		goto clear_xdp_rings;
 	}
-	ice_vsi_assign_bpf_prog(vsi, prog);
+
+	/* assign the prog only when it's not already present on VSI;
+	 * this flow is a subject of both ethtool -L and ndo_bpf flows;
+	 * VSI rebuild that happens under ethtool -L can expose us to
+	 * the bpf_prog refcount issues as we would be swapping same
+	 * bpf_prog pointers from vsi->xdp_prog and calling bpf_prog_put
+	 * on it as it would be treated as an 'old_prog'; for ndo_bpf
+	 * this is not harmful as dev_xdp_install bumps the refcount
+	 * before calling the op exposed by the driver;
+	 */
+	if (!ice_is_xdp_ena_vsi(vsi))
+		ice_vsi_assign_bpf_prog(vsi, prog);
 
 	return 0;
 clear_xdp_rings:
@@ -2785,6 +2796,11 @@ ice_xdp_setup_prog(struct ice_vsi *vsi, struct bpf_prog *prog,
 		if (xdp_ring_err)
 			NL_SET_ERR_MSG_MOD(extack, "Freeing XDP Tx resources failed");
 	} else {
+		/* safe to call even when prog == vsi->xdp_prog as
+		 * dev_xdp_install in net/core/dev.c incremented prog's
+		 * refcount so corresponding bpf_prog_put won't cause
+		 * underflow
+		 */
 		ice_vsi_assign_bpf_prog(vsi, prog);
 	}
 
-- 
2.31.1

Re: [PATCH net 0/2][pull request] Intel Wired LAN Driver Updates 2021-11-22

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Tony Nguyen <anthony.l.nguyen@intel.com>:

On Mon, 22 Nov 2021 10:45:20 -0800 you wrote:
> Maciej Fijalkowski says:
> 
> Here are the two fixes for issues around ethtool's set_channels()
> callback for ice driver. Both are related to XDP resources. First one
> corrects the size of vsi->txq_map that is used to track the usage of Tx
> resources and the second one prevents the wrong refcounting of bpf_prog.
> 
> [...]

Here is the summary with links:
  - [net,1/2] ice: fix vsi->txq_map sizing
    https://git.kernel.org/netdev/net/c/792b2086584f
  - [net,2/2] ice: avoid bpf_prog refcount underflow
    https://git.kernel.org/netdev/net/c/f65ee535df77

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html