netdev - Re: [PATCH v3] vhost_vdpa: fix unmap process in no-batch mode

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Date:   Mon, 24 Apr 2023 11:47:12 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cindy Lu <lulu@...hat.com>
Cc:     mst@...hat.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v3] vhost_vdpa: fix unmap process in no-batch mode

On Thu, Apr 20, 2023 at 11:17 PM Cindy Lu <lulu@...hat.com> wrote:
>
> While using the vdpa device with vIOMMU enabled
> in the guest VM, when the vdpa device bind to vfio-pci and run testpmd
> then system will fail to unmap.
> The test process is
> Load guest VM --> attach to virtio driver--> bind to vfio-pci driver
> So the mapping process is
> 1)batched mode map to normal MR
> 2)batched mode unmapped the normal MR
> 3)unmapped all the memory
> 4)mapped to iommu MR
>
> This error happened in step 3). The iotlb was freed in step 2)
> and the function vhost_vdpa_process_iotlb_msg will return fail
> Which causes failure.
>
> To fix this, we will not remove the AS while the iotlb->nmaps is 0.
> This will free in the vhost_vdpa_clean
>
> Cc: stable@...r.kernel.org
> Fixes: aaca8373c4b1 ("vhost-vdpa: support ASID based IOTLB API")
> Signed-off-by: Cindy Lu <lulu@...hat.com>

Acked-by: Jason Wang <jasowang@...hat.com>

Thanks

> ---
>  drivers/vhost/vdpa.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 7be9d9d8f01c..74c7d1f978b7 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -851,11 +851,7 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v,
>                 if (!v->in_batch)
>                         ops->set_map(vdpa, asid, iotlb);
>         }
> -       /* If we are in the middle of batch processing, delay the free
> -        * of AS until BATCH_END.
> -        */
> -       if (!v->in_batch && !iotlb->nmaps)
> -               vhost_vdpa_remove_as(v, asid);
> +
>  }
>
>  static int vhost_vdpa_va_map(struct vhost_vdpa *v,
> @@ -1112,8 +1108,6 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
>                 if (v->in_batch && ops->set_map)
>                         ops->set_map(vdpa, asid, iotlb);
>                 v->in_batch = false;
> -               if (!iotlb->nmaps)
> -                       vhost_vdpa_remove_as(v, asid);
>                 break;
>         default:
>                 r = -EINVAL;
> --
> 2.34.3
>