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

[Rob Clark]

On Tue, Mar 24, 2026 at 3:20 PM Dmitry Baryshkov
<dmitry.baryshkov@xxxxxxxxxxxxxxxx> wrote:
>
> 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?

yeah, perhaps it should use UERR() instead

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