Re: [PATCH v5 2/9] drm/ttm: Add ttm_bo_access

[Mika Kuoppala <mika.kuoppala@intel.com>]

Matthew Brost <matthew.brost@intel.com> writes:

> On Tue, Oct 22, 2024 at 12:18:52PM +0300, Mika Kuoppala wrote:
>> Matthew Brost <matthew.brost@intel.com> writes:
>> 
>> > 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)
>> >
>> > 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>
>> 
>> With the igt/xe_eudebug* coverage,
>> 
>> Tested-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
>
> Thanks! Is this for the series or just this patch?
>

Whole series applied but the coverage tested only
ttm_bo_access().
-Mika

> Matt
>
>> 
>> > ---
>> >  drivers/gpu/drm/ttm/ttm_bo_util.c | 86 +++++++++++++++++++++++++++++++
>> >  drivers/gpu/drm/ttm/ttm_bo_vm.c   | 65 +----------------------
>> >  include/drm/ttm/ttm_bo.h          |  2 +
>> >  3 files changed, 89 insertions(+), 64 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
>> > index d939925efa81..41bb5a7477d3 100644
>> > --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
>> > +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
>> > @@ -919,3 +919,89 @@ s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev,
>> >  
>> >  	return progress;
>> >  }
>> > +
>> > +static int ttm_bo_access_kmap(struct ttm_buffer_object *bo,
>> > +			      unsigned long offset,
>> > +			      void *buf, int len, int write)
>> > +{
>> > +	unsigned long page = offset >> PAGE_SHIFT;
>> > +	unsigned long bytes_left = len;
>> > +	int ret;
>> > +
>> > +	/* Copy a page at a time, that way no extra virtual address
>> > +	 * mapping is needed
>> > +	 */
>> > +	offset -= page << PAGE_SHIFT;
>> > +	do {
>> > +		unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
>> > +		struct ttm_bo_kmap_obj map;
>> > +		void *ptr;
>> > +		bool is_iomem;
>> > +
>> > +		ret = ttm_bo_kmap(bo, page, 1, &map);
>> > +		if (ret)
>> > +			return ret;
>> > +
>> > +		ptr = (void *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
>> > +		WARN_ON_ONCE(is_iomem);
>> > +		if (write)
>> > +			memcpy(ptr, buf, bytes);
>> > +		else
>> > +			memcpy(buf, ptr, bytes);
>> > +		ttm_bo_kunmap(&map);
>> > +
>> > +		page++;
>> > +		buf += bytes;
>> > +		bytes_left -= bytes;
>> > +		offset = 0;
>> > +	} while (bytes_left);
>> > +
>> > +	return len;
>> > +}
>> > +
>> > +/**
>> > + * 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...).
>> > + *
>> > + * Returns:
>> > + * 0 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)
>> > +{
>> > +	int ret;
>> > +
>> > +	if (len < 1 || (offset + len) > bo->base.size)
>> > +		return -EIO;
>> > +
>> > +	ret = ttm_bo_reserve(bo, true, false, NULL);
>> > +	if (ret)
>> > +		return ret;
>> > +
>> > +	switch (bo->resource->mem_type) {
>> > +	case TTM_PL_SYSTEM:
>> > +		fallthrough;
>> > +	case TTM_PL_TT:
>> > +		ret = ttm_bo_access_kmap(bo, offset, buf, len, write);
>> > +		break;
>> > +	default:
>> > +		if (bo->bdev->funcs->access_memory)
>> > +			ret = bo->bdev->funcs->access_memory
>> > +				(bo, offset, buf, len, write);
>> > +		else
>> > +			ret = -EIO;
>> > +	}
>> > +
>> > +	ttm_bo_unreserve(bo);
>> > +
>> > +	return ret;
>> > +}
>> > +EXPORT_SYMBOL(ttm_bo_access);
>> > diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>> > index 2c699ed1963a..20b1e5f78684 100644
>> > --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
>> > +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>> > @@ -366,45 +366,6 @@ void ttm_bo_vm_close(struct vm_area_struct *vma)
>> >  }
>> >  EXPORT_SYMBOL(ttm_bo_vm_close);
>> >  
>> > -static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
>> > -				 unsigned long offset,
>> > -				 uint8_t *buf, int len, int write)
>> > -{
>> > -	unsigned long page = offset >> PAGE_SHIFT;
>> > -	unsigned long bytes_left = len;
>> > -	int ret;
>> > -
>> > -	/* Copy a page at a time, that way no extra virtual address
>> > -	 * mapping is needed
>> > -	 */
>> > -	offset -= page << PAGE_SHIFT;
>> > -	do {
>> > -		unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
>> > -		struct ttm_bo_kmap_obj map;
>> > -		void *ptr;
>> > -		bool is_iomem;
>> > -
>> > -		ret = ttm_bo_kmap(bo, page, 1, &map);
>> > -		if (ret)
>> > -			return ret;
>> > -
>> > -		ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
>> > -		WARN_ON_ONCE(is_iomem);
>> > -		if (write)
>> > -			memcpy(ptr, buf, bytes);
>> > -		else
>> > -			memcpy(buf, ptr, bytes);
>> > -		ttm_bo_kunmap(&map);
>> > -
>> > -		page++;
>> > -		buf += bytes;
>> > -		bytes_left -= bytes;
>> > -		offset = 0;
>> > -	} while (bytes_left);
>> > -
>> > -	return len;
>> > -}
>> > -
>> >  int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
>> >  		     void *buf, int len, int write)
>> >  {
>> > @@ -412,32 +373,8 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
>> >  	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)
>> > -		return -EIO;
>> >  
>> > -	ret = ttm_bo_reserve(bo, true, false, NULL);
>> > -	if (ret)
>> > -		return ret;
>> > -
>> > -	switch (bo->resource->mem_type) {
>> > -	case TTM_PL_SYSTEM:
>> > -		fallthrough;
>> > -	case TTM_PL_TT:
>> > -		ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
>> > -		break;
>> > -	default:
>> > -		if (bo->bdev->funcs->access_memory)
>> > -			ret = bo->bdev->funcs->access_memory(
>> > -				bo, offset, buf, len, write);
>> > -		else
>> > -			ret = -EIO;
>> > -	}
>> > -
>> > -	ttm_bo_unreserve(bo);
>> > -
>> > -	return ret;
>> > +	return ttm_bo_access(bo, offset, buf, len, write);
>> >  }
>> >  EXPORT_SYMBOL(ttm_bo_vm_access);
>> >  
>> > 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,
>> > -- 
>> > 2.34.1