Re: [PATCH v2 2/7] drm/amdgpu: Implement mmap as GEM object function

[Christian König <christian.koenig@xxxxxxx>]

Am 15.04.21 um 14:11 schrieb Thomas Zimmermann:
> Hi
>
> Am 15.04.21 um 13:38 schrieb Christian König:
> > Am 15.04.21 um 12:17 schrieb Thomas Zimmermann:
> > > Moving the driver-specific mmap code into a GEM object function allows
> > > for using DRM helpers for various mmap callbacks.
> > >
> > > This change resolves several inconsistencies between regular mmap and
> > > prime-based mmap. The vm_ops field in vma is now set for all mmap'ed
> > > areas. Previously it way only set for regular mmap calls, prime-based
> > > mmap used TTM's default vm_ops. The function amdgpu_verify_access() is
> > > no longer being called and therefore removed by this patch.
> > >
> > > As a side effect, amdgpu_ttm_vm_ops and amdgpu_ttm_fault() are now
> > > implemented in amdgpu's GEM code.
> > >
> > > v2:
> > >     * rename amdgpu_ttm_vm_ops and amdgpu_ttm_fault() to
> > >       amdgpu_gem_vm_ops and amdgpu_gem_fault() (Christian)
> > >     * the check for kfd_bo has meanwhile been removed
> > >
> > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> >
> > [SNIP]
> > > +static int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct 
> > > vm_area_struct *vma)
> > > +{
> >
> > Mhm, just double checking this function is now a core GEM function 
> > and not prime specific?
> >
> > If yes maybe drop the _prime part.
>
> No problem, but other functions in the GEM callbacks are also named 
> _prime_. Probably needs a clean-up.

Yeah, some still needs to be renamed. But there shouldn't be any left in 
amdgpu_gem.c

> > > +    struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
> > > +    struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> > > +    unsigned long asize = amdgpu_bo_size(bo);
> > > +
> > > +    if (!vma->vm_file)
> > > +        return -ENODEV;
> > > +
> > > +    if (!adev)
> > > +        return -ENODEV;
> > > +
> > > +    /* Check for valid size. */
> > > +    if (asize < vma->vm_end - vma->vm_start)
> > > +        return -EINVAL;
> >
> > Shouldn't we have that check in the common code?
>
> It's at [1]. I didn't really bother about tidying up the checks 
> themselves. We can drop all these except for the usermm branch below. 
> Same for the radeon patch.

In this case I would just drop that from both amdgpu and radeon.

Thanks,
Christian.

> Best regards
> Thomas
>
> [1] 
> https://elixir.bootlin.com/linux/v5.12-rc7/source/drivers/gpu/drm/drm_gem.c#L1059
>
> > Apart from that looks good to me.
> >
> > Christian.
> >
> > > +
> > > +    if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm) ||
> > > +        (bo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS)) {
> > > +        return -EPERM;
> > > +    }
> > > +
> > > +    return drm_gem_ttm_mmap(obj, vma);
> > > +}
> > > +
> > >   static const struct drm_gem_object_funcs amdgpu_gem_object_funcs = {
> > >       .free = amdgpu_gem_object_free,
> > >       .open = amdgpu_gem_object_open,
> > > @@ -212,6 +266,8 @@ static const struct drm_gem_object_funcs 
> > > amdgpu_gem_object_funcs = {
> > >       .export = amdgpu_gem_prime_export,
> > >       .vmap = drm_gem_ttm_vmap,
> > >       .vunmap = drm_gem_ttm_vunmap,
> > > +    .mmap = amdgpu_gem_prime_mmap,
> > > +    .vm_ops = &amdgpu_gem_vm_ops,
> > >   };
> > >   /*
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > > index 1485f33c3cc7..d4083c19402b 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > > @@ -152,25 +152,6 @@ static void amdgpu_evict_flags(struct 
> > > ttm_buffer_object *bo,
> > >       *placement = abo->placement;
> > >   }
> > > -/**
> > > - * amdgpu_verify_access - Verify access for a mmap call
> > > - *
> > > - * @bo:    The buffer object to map
> > > - * @filp: The file pointer from the process performing the mmap
> > > - *
> > > - * This is called by ttm_bo_mmap() to verify whether a process
> > > - * has the right to mmap a BO to their process space.
> > > - */
> > > -static int amdgpu_verify_access(struct ttm_buffer_object *bo, 
> > > struct file *filp)
> > > -{
> > > -    struct amdgpu_bo *abo = ttm_to_amdgpu_bo(bo);
> > > -
> > > -    if (amdgpu_ttm_tt_get_usermm(bo->ttm))
> > > -        return -EPERM;
> > > -    return drm_vma_node_verify_access(&abo->tbo.base.vma_node,
> > > -                      filp->private_data);
> > > -}
> > > -
> > >   /**
> > >    * amdgpu_ttm_map_buffer - Map memory into the GART windows
> > >    * @bo: buffer object to map
> > > @@ -1522,7 +1503,6 @@ static struct ttm_device_funcs 
> > > amdgpu_bo_driver = {
> > >       .eviction_valuable = amdgpu_ttm_bo_eviction_valuable,
> > >       .evict_flags = &amdgpu_evict_flags,
> > >       .move = &amdgpu_bo_move,
> > > -    .verify_access = &amdgpu_verify_access,
> > >       .delete_mem_notify = &amdgpu_bo_delete_mem_notify,
> > >       .release_notify = &amdgpu_bo_release_notify,
> > >       .io_mem_reserve = &amdgpu_ttm_io_mem_reserve,
> > > @@ -1897,50 +1877,6 @@ void 
> > > amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool 
> > > enable)
> > >       adev->mman.buffer_funcs_enabled = enable;
> > >   }
> > > -static vm_fault_t amdgpu_ttm_fault(struct vm_fault *vmf)
> > > -{
> > > -    struct ttm_buffer_object *bo = vmf->vma->vm_private_data;
> > > -    vm_fault_t ret;
> > > -
> > > -    ret = ttm_bo_vm_reserve(bo, vmf);
> > > -    if (ret)
> > > -        return ret;
> > > -
> > > -    ret = amdgpu_bo_fault_reserve_notify(bo);
> > > -    if (ret)
> > > -        goto unlock;
> > > -
> > > -    ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
> > > -                       TTM_BO_VM_NUM_PREFAULT, 1);
> > > -    if (ret == VM_FAULT_RETRY && !(vmf->flags & 
> > > FAULT_FLAG_RETRY_NOWAIT))
> > > -        return ret;
> > > -
> > > -unlock:
> > > -    dma_resv_unlock(bo->base.resv);
> > > -    return ret;
> > > -}
> > > -
> > > -static const struct vm_operations_struct amdgpu_ttm_vm_ops = {
> > > -    .fault = amdgpu_ttm_fault,
> > > -    .open = ttm_bo_vm_open,
> > > -    .close = ttm_bo_vm_close,
> > > -    .access = ttm_bo_vm_access
> > > -};
> > > -
> > > -int amdgpu_mmap(struct file *filp, struct vm_area_struct *vma)
> > > -{
> > > -    struct drm_file *file_priv = filp->private_data;
> > > -    struct amdgpu_device *adev = drm_to_adev(file_priv->minor->dev);
> > > -    int r;
> > > -
> > > -    r = ttm_bo_mmap(filp, vma, &adev->mman.bdev);
> > > -    if (unlikely(r != 0))
> > > -        return r;
> > > -
> > > -    vma->vm_ops = &amdgpu_ttm_vm_ops;
> > > -    return 0;
> > > -}
> > > -
> > >   int amdgpu_copy_buffer(struct amdgpu_ring *ring, uint64_t src_offset,
> > >                  uint64_t dst_offset, uint32_t byte_count,
> > >                  struct dma_resv *resv,
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h 
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> > > index dec0db8b0b13..6e51faad7371 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> > > @@ -146,7 +146,6 @@ int amdgpu_fill_buffer(struct amdgpu_bo *bo,
> > >               struct dma_resv *resv,
> > >               struct dma_fence **fence);
> > > -int amdgpu_mmap(struct file *filp, struct vm_area_struct *vma);
> > >   int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo);
> > >   int amdgpu_ttm_recover_gart(struct ttm_buffer_object *tbo);
> > >   uint64_t amdgpu_ttm_domain_start(struct amdgpu_device *adev, 
> > > uint32_t type);

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