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From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
To: intel-wired-lan@osuosl.org
Subject: [Intel-wired-lan] [PATCH v2] ixgbe: Add locking to prevent panic when setting sriov_numvfs to zero
Date: Thu, 19 May 2022 11:58:32 +0200	[thread overview]
Message-ID: <YoYUyGULDfBWmGPS@boxer> (raw)
In-Reply-To: <20220519055358.20314-1-piotrx.skajewski@intel.com>

On Thu, May 19, 2022 at 07:53:58AM +0200, Piotr Skajewski wrote:
> 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>

This is a fix for sure. Please target it to net tree and add fixes tag.

> ---
> changes in v2:
>     - replace type spin_lock_bh to spin_lock

Why? Please explain what contexts are being synchronized.k

> 
>  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) {

why this is needed?

also maybe revert the logic and flatten the code:
	if (!adapter->vfinfo)
		goto unlock;
	(...)
unlock:
	spin_unlock(&adapter->vfs_lock);

> +		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
> 
> _______________________________________________
> Intel-wired-lan mailing list
> Intel-wired-lan at osuosl.org
> https://lists.osuosl.org/mailman/listinfo/intel-wired-lan

  reply	other threads:[~2022-05-19  9:58 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-19  5:53 [Intel-wired-lan] [PATCH v2] ixgbe: Add locking to prevent panic when setting sriov_numvfs to zero Piotr Skajewski
2022-05-19  9:58 ` Maciej Fijalkowski [this message]
2022-06-01 13:14 ` Piotr Skajewski
2022-06-14 15:08   ` Maciej Fijalkowski

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