linux-kernel - Re: [PATCH v2] vdpa/mlx5: should not activate virtq object when suspended

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Date:   Tue, 14 Feb 2023 17:20:14 -0800
From:   Si-Wei Liu <si-wei.liu@...cle.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     mst@...hat.com, elic@...dia.com, parav@...dia.com,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, eperezma@...hat.com
Subject: Re: [PATCH v2] vdpa/mlx5: should not activate virtq object when
 suspended



On 2/13/2023 10:20 PM, Jason Wang wrote:
> On Tue, Feb 14, 2023 at 6:48 AM Si-Wei Liu <si-wei.liu@...cle.com> wrote:
>> Otherwise the virtqueue object to instate could point to invalid address
>> that was unmapped from the MTT:
>>
>>    mlx5_core 0000:41:04.2: mlx5_cmd_out_err:782:(pid 8321):
>>    CREATE_GENERAL_OBJECT(0xa00) op_mod(0xd) failed, status
>>    bad parameter(0x3), syndrome (0x5fa1c), err(-22)
>>
>> Fixes: cae15c2ed8e6 ("vdpa/mlx5: Implement susupend virtqueue callback")
>> Cc: Eli Cohen <elic@...dia.com>
>> Signed-off-by: Si-Wei Liu <si-wei.liu@...cle.com>
>>
>> ---
>> v2: removed the change for improving warning message
>> ---
>>   drivers/vdpa/mlx5/net/mlx5_vnet.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> index 3a6dbbc6..d7e8ca0 100644
>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> @@ -165,6 +165,7 @@ struct mlx5_vdpa_net {
>>          u32 cur_num_vqs;
>>          u32 rqt_size;
>>          bool nb_registered;
>> +       bool suspended;
> Any reason we make this net specific? (or is it better to use
> mlx5_vdpa_dev structure?)
Yep, I can make this change, suspend should not be net specific.

>
>
>>          struct notifier_block nb;
>>          struct vdpa_callback config_cb;
>>          struct mlx5_vdpa_wq_ent cvq_ent;
>> @@ -2411,7 +2412,7 @@ static int mlx5_vdpa_change_map(struct mlx5_vdpa_dev *mvdev,
>>          if (err)
>>                  goto err_mr;
>>
>> -       if (!(mvdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
>> +       if (!(mvdev->status & VIRTIO_CONFIG_S_DRIVER_OK) || ndev->suspended)
>>                  goto err_mr;
>>
>>          restore_channels_info(ndev);
>> @@ -2580,6 +2581,7 @@ static int mlx5_vdpa_reset(struct vdpa_device *vdev)
>>          mlx5_vdpa_destroy_mr(&ndev->mvdev);
>>          ndev->mvdev.status = 0;
>>          ndev->cur_num_vqs = 0;
>> +       ndev->suspended = false;
>>          ndev->mvdev.cvq.received_desc = 0;
>>          ndev->mvdev.cvq.completed_desc = 0;
>>          memset(ndev->event_cbs, 0, sizeof(*ndev->event_cbs) * (mvdev->max_vqs + 1));
>> @@ -2815,6 +2817,8 @@ static int mlx5_vdpa_suspend(struct vdpa_device *vdev)
>>          struct mlx5_vdpa_virtqueue *mvq;
>>          int i;
>>
>> +       mlx5_vdpa_info(mvdev, "suspending device\n");
>> +
> Is this better to show the info after the device has been suspended?
I'm not sure, the current convention of this driver (for e.g. 
mlx5_vdpa_reset) is to log info at the function entry to inform some 
action is about to happen, and log a warning if running into any 
failure; otherwise if no subsequent warning but other logs following the 
info notice, it means the action has been successfully done. I thought 
at least there's some value to log at the start of the function just in 
case it's getting stuck in the middle.

Thanks,
-Siwei

>
> Thanks
>
>>          down_write(&ndev->reslock);
>>          ndev->nb_registered = false;
>>          mlx5_notifier_unregister(mvdev->mdev, &ndev->nb);
>> @@ -2824,6 +2828,7 @@ static int mlx5_vdpa_suspend(struct vdpa_device *vdev)
>>                  suspend_vq(ndev, mvq);
>>          }
>>          mlx5_vdpa_cvq_suspend(mvdev);
>> +       ndev->suspended = true;
>>          up_write(&ndev->reslock);
>>          return 0;
>>   }
>> --
>> 1.8.3.1
>>