Re: [PATCH 1/2] ice: Fix race conditions between virtchnl handling and VF ndo ops

[Greg KH <greg@kroah.com>]

On Mon, Feb 28, 2022 at 12:46:59PM -0800, Jacob Keller wrote:
> From: Brett Creeley <brett.creeley@intel.com>
> 
> commit e6ba5273d4ede03d075d7a116b8edad1f6115f4d upstream.
> 
> [I had to fix the cherry-pick manually as the patch added a line around
> some context that was missing.]
> 
> The VF can be configured via the PF's ndo ops at the same time the PF is
> receiving/handling virtchnl messages. This has many issues, with
> one of them being the ndo op could be actively resetting a VF (i.e.
> resetting it to the default state and deleting/re-adding the VF's VSI)
> while a virtchnl message is being handled. The following error was seen
> because a VF ndo op was used to change a VF's trust setting while the
> VIRTCHNL_OP_CONFIG_VSI_QUEUES was ongoing:
> 
> [35274.192484] ice 0000:88:00.0: Failed to set LAN Tx queue context, error: ICE_ERR_PARAM
> [35274.193074] ice 0000:88:00.0: VF 0 failed opcode 6, retval: -5
> [35274.193640] iavf 0000:88:01.0: PF returned error -5 (IAVF_ERR_PARAM) to our request 6
> 
> Fix this by making sure the virtchnl handling and VF ndo ops that
> trigger VF resets cannot run concurrently. This is done by adding a
> struct mutex cfg_lock to each VF structure. For VF ndo ops, the mutex
> will be locked around the critical operations and VFR. Since the ndo ops
> will trigger a VFR, the virtchnl thread will use mutex_trylock(). This
> is done because if any other thread (i.e. VF ndo op) has the mutex, then
> that means the current VF message being handled is no longer valid, so
> just ignore it.
> 
> This issue can be seen using the following commands:
> 
> for i in {0..50}; do
>         rmmod ice
>         modprobe ice
> 
>         sleep 1
> 
>         echo 1 > /sys/class/net/ens785f0/device/sriov_numvfs
>         echo 1 > /sys/class/net/ens785f1/device/sriov_numvfs
> 
>         ip link set ens785f1 vf 0 trust on
>         ip link set ens785f0 vf 0 trust on
> 
>         sleep 2
> 
>         echo 0 > /sys/class/net/ens785f0/device/sriov_numvfs
>         echo 0 > /sys/class/net/ens785f1/device/sriov_numvfs
>         sleep 1
>         echo 1 > /sys/class/net/ens785f0/device/sriov_numvfs
>         echo 1 > /sys/class/net/ens785f1/device/sriov_numvfs
> 
>         ip link set ens785f1 vf 0 trust on
>         ip link set ens785f0 vf 0 trust on
> done
> 
> Fixes: 7c710869d64e ("ice: Add handlers for VF netdevice operations")
> Cc: <stable@vger.kernel.org> # 5.14.x
> Signed-off-by: Brett Creeley <brett.creeley@intel.com>
> Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> ---
> This should apply to 5.14.x

5.14 is long end-of-life, always look at the kernel.org page if you are
curious what the "active" kernel trees are.

thanks,

greg k-h