Re: [PATCH 1/2] drm/msm: Disallow foreign mapping of _NO_SHARE

[Dmitry Baryshkov]

On Tue, Mar 24, 2026 at 03:05:17PM -0700, Rob Clark wrote:
> This restriction applies to mapping of _NO_SHARE objs in the kms vm as
> well as importing/exporting BOs.  Since the DPU has it's own VM, scanout
> counts as "exporting" a BO from outside of it's host VM.
> 
> Signed-off-by: Rob Clark <robin.clark@xxxxxxxxxxxxxxxx>
> ---
> v2: Fix issue with MAP_NULL
> 
>  drivers/gpu/drm/msm/msm_gem_vma.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gem_vma.c b/drivers/gpu/drm/msm/msm_gem_vma.c
> index 1c6b0920c0d8..43d61e0919bd 100644
> --- a/drivers/gpu/drm/msm/msm_gem_vma.c
> +++ b/drivers/gpu/drm/msm/msm_gem_vma.c
> @@ -373,6 +373,12 @@ msm_gem_vma_new(struct drm_gpuvm *gpuvm, struct drm_gem_object *obj,
>  	struct msm_gem_vma *vma;
>  	int ret;
>  
> +	/* _NO_SHARE objs cannot be mapped outside of their "host" vm: */
> +	if (obj && (to_msm_bo(obj)->flags & MSM_BO_NO_SHARE) &&
> +	    GEM_WARN_ON(obj->resv != drm_gpuvm_resv(gpuvm))) {

Can this be used to spam the logs?

> +		return ERR_PTR(-EINVAL);
> +	}
> +
>  	drm_gpuvm_resv_assert_held(&vm->base);
>  
>  	vma = kzalloc(sizeof(*vma), GFP_KERNEL);
> -- 
> 2.53.0
> 

-- 
With best wishes
Dmitry