Re: [PATCH] drm/i915/gvt: Release GGTT MM if scratch page setup fails

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

On Tue, Nov 03, 2026 at 06:54:07AM +0000, Wentao Liang wrote:
> intel_vgpu_init_gtt() creates the GGTT MM before allocating the scratch
> page table tree. If scratch page allocation or DMA mapping fails,
> create_scratch_page_tree() releases its own pages, but the GGTT MM and
> its virtual GGTT and host GGTT buffers remain allocated. The caller
> skips intel_vgpu_clean_gtt() when intel_vgpu_init_gtt() fails.
> 
> Drop the GGTT MM reference and clear its pointer before returning the
> scratch page initialization error.
>
> Fixes: 3b6411c2c205 ("drm/i915/gvt: implement scratch page table tree for shadow PPGTT")
> Cc: stable@vger.kernel.org
> Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
> ---
>  drivers/gpu/drm/i915/gvt/gtt.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
> index 5056a5887b31..17d61548ec05 100644
> --- a/drivers/gpu/drm/i915/gvt/gtt.c
> +++ b/drivers/gpu/drm/i915/gvt/gtt.c
> @@ -2403,6 +2403,7 @@ static int create_scratch_page_tree(struct intel_vgpu *vgpu)
>  int intel_vgpu_init_gtt(struct intel_vgpu *vgpu)
>  {
>  	struct intel_vgpu_gtt *gtt = &vgpu->gtt;
> +	int ret;
>  
>  	INIT_RADIX_TREE(&gtt->spt_tree, GFP_KERNEL);
>  
> @@ -2420,7 +2421,13 @@ int intel_vgpu_init_gtt(struct intel_vgpu *vgpu)
>  
>  	INIT_LIST_HEAD(&gtt->ggtt_mm->ggtt_mm.partial_pte_list);
>  
> -	return create_scratch_page_tree(vgpu);
> +	ret = create_scratch_page_tree(vgpu);
> +	if (ret) {
> +		intel_vgpu_destroy_mm(gtt->ggtt_mm);
> +		gtt->ggtt_mm = NULL;
> +	}

Better to just call intel_vgpu_destroy_ggtt_mm(vgpu) which is more
aligned as for ggtt mm handling.

The issue you identified with AI tool might make sense, but pls learn
how to work with kernel community first.

> +
> +	return ret;
>  }
>  
>  void intel_vgpu_destroy_all_ppgtt_mm(struct intel_vgpu *vgpu)
> -- 
> 2.34.1