Re: [[RESEND] iommufd PATCH v2 1/2] i915/gvt: Move gvt mapping cache initialization to intel_vgpu_init_dev()

[Zhenyu Wang <zhenyuw@linux.intel.com>]

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On 2022.11.29 02:58:30 -0800, Yi Liu wrote:
> vfio container registers .dma_unmap() callback after the device is opened.
> So it's fine for mdev drivers to initialize internal mapping cache in
> .open_device(). See vfio_device_container_register().
> 
> Now with iommufd an access ops with an unmap callback is registered
> when the device is bound to iommufd which is before .open_device()
> is called. This implies gvt's .dma_unmap() could be called before its
> internal mapping cache is initialized.
> 
> The fix is moving gvt mapping cache initialization to vGPU init. While
> at it also move ptable initialization together.
> 
> Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> Cc: Zhi Wang <zhi.a.wang@intel.com>
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: intel-gvt-dev@lists.freedesktop.org
> Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/kvmgt.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 7a45e5360caf..f563e5dbe66f 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -671,9 +671,6 @@ static int intel_vgpu_open_device(struct vfio_device *vfio_dev)
>  
>  	vgpu->attached = true;
>  
> -	kvmgt_protect_table_init(vgpu);
> -	gvt_cache_init(vgpu);
> -
>  	vgpu->track_node.track_write = kvmgt_page_track_write;
>  	vgpu->track_node.track_flush_slot = kvmgt_page_track_flush_slot;
>  	kvm_page_track_register_notifier(vgpu->vfio_device.kvm,
> @@ -1451,9 +1448,17 @@ static int intel_vgpu_init_dev(struct vfio_device *vfio_dev)
>  	struct intel_vgpu *vgpu = vfio_dev_to_vgpu(vfio_dev);
>  	struct intel_vgpu_type *type =
>  		container_of(mdev->type, struct intel_vgpu_type, type);
> +	int ret;
>  
>  	vgpu->gvt = kdev_to_i915(mdev->type->parent->dev)->gvt;
> -	return intel_gvt_create_vgpu(vgpu, type->conf);
> +	ret = intel_gvt_create_vgpu(vgpu, type->conf);
> +	if (ret)
> +		return ret;
> +
> +	kvmgt_protect_table_init(vgpu);
> +	gvt_cache_init(vgpu);
> +
> +	return 0;

I'm fine with this change, but could we add some sanity check at close
time to ensure we clean up any internal cache? Btw, do we need to reset
rbtree root pointer?

>  }
>  
>  static void intel_vgpu_release_dev(struct vfio_device *vfio_dev)
> -- 
> 2.34.1
> 

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