[PATCH v3 1/1] drm/ttm: Fix COW check

[Alex Deucher]

On Tue, Jul 13, 2021 at 2:57 AM Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
>
>
>
> Am 13.07.21 um 00:06 schrieb Felix Kuehling:
> > KFD Thunk maps invisible VRAM BOs with PROT_NONE, MAP_PRIVATE.
> > is_cow_mapping returns true for these mappings. Add a check for
> > vm_flags & VM_WRITE to avoid mmap failures on private read-only or
> > PROT_NONE mappings.
> >
> > v2: protect against mprotect making a mapping writable after the fact
> > v3: update driver-specific vm_operations_structs
> >
> > Fixes: f91142c62161 ("drm/ttm: nuke VM_MIXEDMAP on BO mappings v3")
> > Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> > Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>
> Reviewed-by: Christian König <christian.koenig at amd.com>

Are you planning to push this to drm-misc?

Alex

>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c  |  3 ++-
> >   drivers/gpu/drm/nouveau/nouveau_gem.c    |  3 ++-
> >   drivers/gpu/drm/radeon/radeon_gem.c      |  3 ++-
> >   drivers/gpu/drm/ttm/ttm_bo_vm.c          | 14 +++++++++++++-
> >   drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c |  1 +
> >   include/drm/ttm/ttm_bo_api.h             |  4 ++++
> >   6 files changed, 24 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> > index b3404c43a911..1aa750a6a5d2 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> > @@ -79,7 +79,8 @@ static const struct vm_operations_struct amdgpu_gem_vm_ops = {
> >       .fault = amdgpu_gem_fault,
> >       .open = ttm_bo_vm_open,
> >       .close = ttm_bo_vm_close,
> > -     .access = ttm_bo_vm_access
> > +     .access = ttm_bo_vm_access,
> > +     .mprotect = ttm_bo_vm_mprotect
> >   };
> >
> >   static void amdgpu_gem_object_free(struct drm_gem_object *gobj)
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
> > index 5b27845075a1..164ea564bb7a 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
> > @@ -70,7 +70,8 @@ static const struct vm_operations_struct nouveau_ttm_vm_ops = {
> >       .fault = nouveau_ttm_fault,
> >       .open = ttm_bo_vm_open,
> >       .close = ttm_bo_vm_close,
> > -     .access = ttm_bo_vm_access
> > +     .access = ttm_bo_vm_access,
> > +     .mprotect = ttm_bo_vm_mprotect
> >   };
> >
> >   void
> > diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
> > index 458f92a70887..c19ad07eb7b5 100644
> > --- a/drivers/gpu/drm/radeon/radeon_gem.c
> > +++ b/drivers/gpu/drm/radeon/radeon_gem.c
> > @@ -77,7 +77,8 @@ static const struct vm_operations_struct radeon_gem_vm_ops = {
> >       .fault = radeon_gem_fault,
> >       .open = ttm_bo_vm_open,
> >       .close = ttm_bo_vm_close,
> > -     .access = ttm_bo_vm_access
> > +     .access = ttm_bo_vm_access,
> > +     .mprotect = ttm_bo_vm_mprotect
> >   };
> >
> >   static void radeon_gem_object_free(struct drm_gem_object *gobj)
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > index f56be5bc0861..fb325bad5db6 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > @@ -542,17 +542,29 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> >   }
> >   EXPORT_SYMBOL(ttm_bo_vm_access);
> >
> > +int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,
> > +                    unsigned long end, unsigned long newflags)
> > +{
> > +     /* Enforce no COW since would have really strange behavior with it. */
> > +     if (is_cow_mapping(newflags) && (newflags & VM_WRITE))
> > +             return -EINVAL;
> > +
> > +     return 0;
> > +}
> > +EXPORT_SYMBOL(ttm_bo_vm_mprotect);
> > +
> >   static const struct vm_operations_struct ttm_bo_vm_ops = {
> >       .fault = ttm_bo_vm_fault,
> >       .open = ttm_bo_vm_open,
> >       .close = ttm_bo_vm_close,
> >       .access = ttm_bo_vm_access,
> > +     .mprotect = ttm_bo_vm_mprotect,
> >   };
> >
> >   int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
> >   {
> >       /* Enforce no COW since would have really strange behavior with it. */
> > -     if (is_cow_mapping(vma->vm_flags))
> > +     if (is_cow_mapping(vma->vm_flags) && (vma->vm_flags & VM_WRITE))
> >               return -EINVAL;
> >
> >       ttm_bo_get(bo);
> > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> > index e6b1f98ec99f..e4bf7dc99320 100644
> > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> > @@ -61,6 +61,7 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
> >               .fault = vmw_bo_vm_fault,
> >               .open = ttm_bo_vm_open,
> >               .close = ttm_bo_vm_close,
> > +             .mprotect = ttm_bo_vm_mprotect,
> >   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> >               .huge_fault = vmw_bo_vm_huge_fault,
> >   #endif
> > diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> > index f681bbdbc698..40eb95875355 100644
> > --- a/include/drm/ttm/ttm_bo_api.h
> > +++ b/include/drm/ttm/ttm_bo_api.h
> > @@ -605,6 +605,10 @@ void ttm_bo_vm_close(struct vm_area_struct *vma);
> >
> >   int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> >                    void *buf, int len, int write);
> > +
> > +int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,
> > +                    unsigned long end, unsigned long newflags);
> > +
> >   bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all);
> >
> >   vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot);
>