Re: [PATCH v7 2/8] drm/ttm: Add ttm_bo_access

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Nov 27, 2024 at 02:19:32PM +0100, Christian König wrote:
> Am 26.11.24 um 18:46 schrieb Matthew Brost:
> > Non-contiguous VRAM cannot easily be mapped in TTM nor can non-visible
> > VRAM easily be accessed. Add ttm_bo_access, which is similar to
> > ttm_bo_vm_access, to access such memory.
> > 
> > v4:
> >   - Fix checkpatch warnings (CI)
> > v5:
> >   - Fix checkpatch warnings (CI)
> > v6:
> >   - Fix kernel doc (Auld)
> > v7:
> >   - Move ttm_bo_access to ttm_bo_vm.c (Christian)
> > 
> > Cc: Christian König <christian.koenig@amd.com>
> > Reported-by: Christoph Manszewski <christoph.manszewski@intel.com>
> > Suggested-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > Tested-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> > Reviewed-by: Matthew Auld <matthew.auld@intel.com>
> 
> Reviewed-by: Christian König <christian.koenig@amd.com>

Thank you!

Ack on get this through drm-xe-next?

drm-misc-maintainers?

> 
> > ---
> >   drivers/gpu/drm/ttm/ttm_bo_vm.c | 40 ++++++++++++++++++++++++++-------
> >   include/drm/ttm/ttm_bo.h        |  2 ++
> >   2 files changed, 34 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > index 2c699ed1963a..f02d3966cc84 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > @@ -405,13 +405,25 @@ static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
> >   	return len;
> >   }
> > -int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> > -		     void *buf, int len, int write)
> > +/**
> > + * ttm_bo_access - Helper to access a buffer object
> > + *
> > + * @bo: ttm buffer object
> > + * @offset: access offset into buffer object
> > + * @buf: pointer to caller memory to read into or write from
> > + * @len: length of access
> > + * @write: write access
> > + *
> > + * Utility function to access a buffer object. Useful when buffer object cannot
> > + * be easily mapped (non-contiguous, non-visible, etc...). Should not directly
> > + * be exported to user space via a peak / poke interface.
> > + *
> > + * Returns:
> > + * @len if successful, negative error code on failure.
> > + */
> > +int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
> > +		  void *buf, int len, int write)
> >   {
> > -	struct ttm_buffer_object *bo = vma->vm_private_data;
> > -	unsigned long offset = (addr) - vma->vm_start +
> > -		((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
> > -		 << PAGE_SHIFT);
> >   	int ret;
> >   	if (len < 1 || (offset + len) > bo->base.size)
> > @@ -429,8 +441,8 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> >   		break;
> >   	default:
> >   		if (bo->bdev->funcs->access_memory)
> > -			ret = bo->bdev->funcs->access_memory(
> > -				bo, offset, buf, len, write);
> > +			ret = bo->bdev->funcs->access_memory
> > +				(bo, offset, buf, len, write);
> >   		else
> >   			ret = -EIO;
> >   	}
> > @@ -439,6 +451,18 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> >   	return ret;
> >   }
> > +EXPORT_SYMBOL(ttm_bo_access);
> > +
> > +int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> > +		     void *buf, int len, int write)
> > +{
> > +	struct ttm_buffer_object *bo = vma->vm_private_data;
> > +	unsigned long offset = (addr) - vma->vm_start +
> > +		((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
> > +		 << PAGE_SHIFT);
> > +
> > +	return ttm_bo_access(bo, offset, buf, len, write);
> > +}
> >   EXPORT_SYMBOL(ttm_bo_vm_access);
> >   static const struct vm_operations_struct ttm_bo_vm_ops = {
> > diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
> > index 5804408815be..8ea11cd8df39 100644
> > --- a/include/drm/ttm/ttm_bo.h
> > +++ b/include/drm/ttm/ttm_bo.h
> > @@ -421,6 +421,8 @@ void ttm_bo_unpin(struct ttm_buffer_object *bo);
> >   int ttm_bo_evict_first(struct ttm_device *bdev,
> >   		       struct ttm_resource_manager *man,
> >   		       struct ttm_operation_ctx *ctx);
> > +int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
> > +		  void *buf, int len, int write);
> >   vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
> >   			     struct vm_fault *vmf);
> >   vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>