[Intel-wired-lan] [PATCH v2] ixgbe: Add locking to prevent panic when setting sriov_numvfs to zero

[Piotr Skajewski <piotrx.skajewski@intel.com>]

It is possible to disable VFs while the PF driver is processing requests
from the VF driver.  This can result in a panic.

BUG: unable to handle kernel paging request at 000000000000106c
PGD 0 P4D 0
Oops: 0000 [#1] SMP NOPTI
CPU: 8 PID: 0 Comm: swapper/8 Kdump: loaded Tainted: G I      --------- -
Hardware name: Dell Inc. PowerEdge R740/06WXJT, BIOS 2.8.2 08/27/2020
RIP: 0010:ixgbe_msg_task+0x4c8/0x1690 [ixgbe]
Code: 00 00 48 8d 04 40 48 c1 e0 05 89 7c 24 24 89 fd 48 89 44 24 10 83 ff
01 0f 84 b8 04 00 00 4c 8b 64 24 10 4d 03 a5 48 22 00 00 <41> 80 7c 24 4c
00 0f 84 8a 03 00 00 0f b7 c7 83 f8 08 0f 84 8f 0a
RSP: 0018:ffffb337869f8df8 EFLAGS: 00010002
RAX: 0000000000001020 RBX: 0000000000000000 RCX: 000000000000002b
RDX: 0000000000000002 RSI: 0000000000000008 RDI: 0000000000000006
RBP: 0000000000000006 R08: 0000000000000002 R09: 0000000000029780
R10: 00006957d8f42832 R11: 0000000000000000 R12: 0000000000001020
R13: ffff8a00e8978ac0 R14: 000000000000002b R15: ffff8a00e8979c80
FS:  0000000000000000(0000) GS:ffff8a07dfd00000(0000) knlGS:00000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000106c CR3: 0000000063e10004 CR4: 00000000007726e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <IRQ>
 ? ttwu_do_wakeup+0x19/0x140
 ? try_to_wake_up+0x1cd/0x550
 ? ixgbevf_update_xcast_mode+0x71/0xc0 [ixgbevf]
 ixgbe_msix_other+0x17e/0x310 [ixgbe]
 __handle_irq_event_percpu+0x40/0x180
 handle_irq_event_percpu+0x30/0x80
 handle_irq_event+0x36/0x53
 handle_edge_irq+0x82/0x190
 handle_irq+0x1c/0x30
 do_IRQ+0x49/0xd0
 common_interrupt+0xf/0xf

This can be eventually be reproduced with the following script:

while :
do
    echo 63 > /sys/class/net/<devname>/device/sriov_numvfs
    sleep 1
    echo 0 > /sys/class/net/<devname>/device/sriov_numvfs
    sleep 1
done

Add lock when disabling SR-IOV to prevent process VF mailbox communication.

Signed-off-by: Piotr Skajewski <piotrx.skajewski@intel.com>
---
changes in v2:
    - replace type spin_lock_bh to spin_lock

 drivers/net/ethernet/intel/ixgbe/ixgbe.h      |  1 +
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |  3 ++
 .../net/ethernet/intel/ixgbe/ixgbe_sriov.c    | 28 ++++++++++++-------
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe.h b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
index 921a4d977d65..8813b4dd6872 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe.h
@@ -779,6 +779,7 @@ struct ixgbe_adapter {
 #ifdef CONFIG_IXGBE_IPSEC
 	struct ixgbe_ipsec *ipsec;
 #endif /* CONFIG_IXGBE_IPSEC */
+	spinlock_t vfs_lock;
 };
 
 static inline int ixgbe_determine_xdp_q_idx(int cpu)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index c4a4954aa317..6c403f112d29 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -6402,6 +6402,9 @@ static int ixgbe_sw_init(struct ixgbe_adapter *adapter,
 	/* n-tuple support exists, always init our spinlock */
 	spin_lock_init(&adapter->fdir_perfect_lock);
 
+	/* init spinlock to avoid concurrency of VF resources */
+	spin_lock_init(&adapter->vfs_lock);
+
 #ifdef CONFIG_IXGBE_DCB
 	ixgbe_init_dcb(adapter);
 #endif
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
index 7f11c0a8e7a9..6f583df19635 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
@@ -207,6 +207,8 @@ int ixgbe_disable_sriov(struct ixgbe_adapter *adapter)
 	unsigned int num_vfs = adapter->num_vfs, vf;
 	int rss;
 
+	spin_lock(&adapter->vfs_lock);
+
 	/* set num VFs to 0 to prevent access to vfinfo */
 	adapter->num_vfs = 0;
 
@@ -228,6 +230,8 @@ int ixgbe_disable_sriov(struct ixgbe_adapter *adapter)
 	kfree(adapter->mv_list);
 	adapter->mv_list = NULL;
 
+	spin_unlock(&adapter->vfs_lock);
+
 	/* if SR-IOV is already disabled then there is nothing to do */
 	if (!(adapter->flags & IXGBE_FLAG_SRIOV_ENABLED))
 		return 0;
@@ -1357,19 +1361,23 @@ void ixgbe_msg_task(struct ixgbe_adapter *adapter)
 	struct ixgbe_hw *hw = &adapter->hw;
 	u32 vf;
 
-	for (vf = 0; vf < adapter->num_vfs; vf++) {
-		/* process any reset requests */
-		if (!ixgbe_check_for_rst(hw, vf))
-			ixgbe_vf_reset_event(adapter, vf);
+	spin_lock(&adapter->vfs_lock);
+	if (adapter->vfinfo) {
+		for (vf = 0; vf < adapter->num_vfs; vf++) {
+			/* process any reset requests */
+			if (!ixgbe_check_for_rst(hw, vf))
+				ixgbe_vf_reset_event(adapter, vf);
 
-		/* process any messages pending */
-		if (!ixgbe_check_for_msg(hw, vf))
-			ixgbe_rcv_msg_from_vf(adapter, vf);
+			/* process any messages pending */
+			if (!ixgbe_check_for_msg(hw, vf))
+				ixgbe_rcv_msg_from_vf(adapter, vf);
 
-		/* process any acks */
-		if (!ixgbe_check_for_ack(hw, vf))
-			ixgbe_rcv_ack_from_vf(adapter, vf);
+			/* process any acks */
+			if (!ixgbe_check_for_ack(hw, vf))
+				ixgbe_rcv_ack_from_vf(adapter, vf);
+		}
 	}
+	spin_unlock(&adapter->vfs_lock);
 }
 
 static inline void ixgbe_ping_vf(struct ixgbe_adapter *adapter, int vf)
-- 
2.35.0.rc0