[PATCH v7 6/8] drm/xe: Use ttm_bo_access in xe_vm_snapshot_capture_delayed

[Thomas Hellström]

Hi, Matthew

On Tue, 2024-11-26 at 09:46 -0800, Matthew Brost wrote:
> Non-contiguous mapping of BO in VRAM doesn't work, use ttm_bo_access
> instead.
> 
> v2:
>  - Fix error handling
> 
> Fixes: 0eb2a18a8fad ("drm/xe: Implement VM snapshot support for BO's
> and userptr")

I've been holding this patch off from stable since it relies on the
actual access() ttm callback being implemented for xe, and I don't
believe it is.

Now with the first PR for 6.14, this will start getting backport
requests from the stable maintainers and if we don't block them, I
guess functionality might break?

Would it be possible to provide a sane backport of this functionality
on top of 6.13-rc? (the drm-xe-fixes branch)?

Thanks,
Thomas


> Suggested-by: Matthew Auld <matthew.auld at intel.com>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> Reviewed-by: Matthew Auld <matthew.auld at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_vm.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 1d7faeba157e..2492750505d6 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -3309,7 +3309,6 @@ void xe_vm_snapshot_capture_delayed(struct
> xe_vm_snapshot *snap)
>  
>  	for (int i = 0; i < snap->num_snaps; i++) {
>  		struct xe_bo *bo = snap->snap[i].bo;
> -		struct iosys_map src;
>  		int err;
>  
>  		if (IS_ERR(snap->snap[i].data))
> @@ -3322,16 +3321,12 @@ void xe_vm_snapshot_capture_delayed(struct
> xe_vm_snapshot *snap)
>  		}
>  
>  		if (bo) {
> -			xe_bo_lock(bo, false);
> -			err = ttm_bo_vmap(&bo->ttm, &src);
> -			if (!err) {
> -				xe_map_memcpy_from(xe_bo_device(bo),
> -						   snap-
> >snap[i].data,
> -						   &src, snap-
> >snap[i].bo_ofs,
> -						   snap-
> >snap[i].len);
> -				ttm_bo_vunmap(&bo->ttm, &src);
> -			}
> -			xe_bo_unlock(bo);
> +			err = ttm_bo_access(&bo->ttm, snap-
> >snap[i].bo_ofs,
> +					    snap->snap[i].data,
> snap->snap[i].len, 0);
> +			if (!(err < 0) && err != snap->snap[i].len)
> +				err = -EIO;
> +			else if (!(err < 0))
> +				err = 0;
>  		} else {
>  			void __user *userptr = (void __user
> *)(size_t)snap->snap[i].bo_ofs;
>